Simulation Models, GIS and Nonpoint-Source Pollution (II)

The relationship between plant roots and interrill soil erosion is important in dynamic soil erosion predictions. Rainstorm simulations of similar intensity (63.5 mm h-1) were conducted in the summer of 1989 on 1 by 1 m field plots of Cecil sandy loam (clayey, kaolinitic, thermic Typic Kanhapludult) to study the effect of different root length densities, L(v) (cm cm-3), of corn (Zea mays L.), during vegetative, preanthesis, and anthesis plant developmental stages on interrill soil erosion. Sediment loss and runoff data were assigned to treatments, L(va), on the basis of L(v) range to reduce rooting variability associated with plant developmental stage. To avoid confounding by canopy cover, corn plants were cut at the stem base and removed for the first four sets of simulations. A reference set of simulations was performed on a fallow plot containing no roots, L(va). Runoff and detached sediment were collected in buckets from each plot during successive 5-min intervals over a 1-h period. Thirty cores, 5 cm in diam. and 5 cm deep, were taken from each 1-m2 plot and roots were washed from the cores and measured. Means for runoff and detached sediment were generally not significantly different for the high L(v) or L(va), and L(va0). When L(va) was < 1.5 cm cm-3, runoff and detached sediment were significantly lower during the first 30 min of simulated rainfall. High densities of live corn roots did not reduce interrill soil erosion from a moldboard-plowed Cecil sandy loam. NAL Call No.: 56.9-So3 ***************************************************************** 73. A hedonic analysis of herbicides: do user safety and water quality matter. Beach, E. D.; Carlson, G. A. Am-j-agric-econ. Ames, Iowa : American Agricultural Economics Association. Aug 1993. v. 75(3) p. 612-623. Includes references. Descriptors: herbicides-; weed-control; water-quality; safety-; farmers'-attitudes; econometric-models; zea-mays; glycine-max; decision-analysis; usa-; arkansas-; iowa-; north-carolina; ohio-; broadleaf-weeds Abstract: Farmers may value water quality and user safety characteristics of herbicides as they select among products to obtain weed control. Expenditures per application in the U.S. corn and soybean herbicide markets are explained by several safety characteristics in addition to market and weed control characteristics. The explicit inclusion of safety characteristics in the farm decision model indicates that not all safety aspects of pesticide use are external to farmers. Leaching potential and user toxicity are statistically significant, but their elasticities are small relative to broadleaf and grass weed control efficacy. NAL Call No.: 280.8-J822 ***************************************************************** 74. Human intestinal cell line Caco-2: a useful model for studying cellular and molecular regulation of biotin uptake. Ma, T. Y.; Dyer, D. L.; Said, H. M. Biochim-biophys-acta v.1189, p.81-88. (1994). Includes references. Descriptors: biotin-; nutrient-uptake; regulation-; transport-processes; intestines-; cell-lines Abstract: The mechanisms of enterocyte and molecular regulation of biotin uptake are poorly understood. An intestinal cell line possessing the transport characteristics of native intestinal cells is highly desirable to investigate the finer details of the cellular processing and molecular regulation of biotin transport. In the present study, we investigated the uptake of the water-soluble vitamin biotin by a human intestinal cell line Caco-2. Uptake of both low (4 nM) and high (20 micromolar) concentrations of biotin by confluent monolayers of Caco-2 cells was appreciable and linear for up to 10 min of incubation. Replacement of Na+ in the incubation medium with other monovalent cations -K+, choline, Li+ and NH4+ -caused a significant inhibition of biotin uptake; a relatively lesser inhibition was seen with Li+. Initial rate of uptake of biotin was temperature-dependent and saturable as a function of concentration at 37 degrees C but not at 4 degrees C. The Vmax and apparent Km of the temperature-dependent saturable process were 520 pmol/mg protein per min and 9.5 micromolars, respectively. The addition of unlabeled biotin and the structural analogue desthiobiotin to the incubation media caused a significant inhibition of the uptake of [3H]biotin. The inhibitory effect of desthiobiotin was competitive in nature with an inhibition constant (Ki) of 41 micromolar. Biocytin, on the other hand, was a weak inhibitor and biotin methyl ester and diaminobiotin did not have any effect. Pretreatment of Caco-2 cells with the monovalent cation ionophore gramicidin and the Na+, K+-ATPase inhibitor ouabain caused significant inhibition of biotin uptake. Pretreatment with the K+ ionophore valinomycin did not affect biotin. biotinto Na+ coupling was found to be 1:1. Growing confluent Caco-2 cells in a biotin-deficient environment resulted in rapid up-regulation of biotin transport with a marked increase (258%) in the Vmax of biotin uptake. These findings demonstrate that biotin uptake by Caco-2 cells is via a carrier-mediated systm. This system is temperature-dependent, driven by Na+-gradient and is regulated by the substrate level. These in-vitro findings are very similar to and further confirm previous findings in human and animal studies and dispute other findings previously reported for Caco-2 cells; the present study also demonstrates the suitability of this system for further characterization of the cellular and molecular regulation of biotin uptake. NAL Call No.: 381-B522 ***************************************************************** 75. Hystem-EXTRAN: improvements to EPA-EXTRAN. Fuchs, L.; Scheffer, C. Water-sci-technol v.29, p.63-71. (1994). Selected Proceedings of the 6th International Conference on Urban Storm Drainage, September 12-17, 1993, Niagara Falls, Canada / edited by J.C. Marsalek and H.C. Torno. Descriptors: rain-; runoff-; hydrology-; water-management; simulation-models NAL Call No.: TD420.A1P7 ***************************************************************** 76. Identification of road salt contamination using multiple regression and GIS. Mattson, M. D.; Godfrey, P. J. Environ-manage. New York, Springer-Verlag. Sept/Oct 1994. v. 18 (5) p. 767-773. Includes references. Descriptors: streams-; salt-; sodium-chloride; water-pollution; regression-analysis; geographical-information-systems; massachusettsNAL Call No.: HC79.E5E5 ***************************************************************** 77. The impact of changes in the runoff formulation of a general circulation model on surface and near-surface parameters. Viterbo, P.; Illari, L. J-hydrol v.155, p.325-336. (1994). Special Issue: Mesoscale Hydrology and General Circulation Models. Descriptors: soil-water; runoff-; simulation-models; precipitation-; infiltration-; evapotranspiration-; air-temperature; geographical-distribution; forecastingAbstract: The surface and near-surface properties of the European Centre for Medium Range Weather Forecasting (ECMWF) general circulation model are shown to be sensitive to the parametrization of runoff. If a border subgrid-scale distribution of precipitation is assumed when computing runoff, the infiltration increases, more water becomes available for evaporation and the model surface cools. The averaged Bowen ratio over land is shown to decrease from 1.5 to 0.9 in a Northern Hemisphere summer experiment. Possible implications for the estimation of soil moisture and evapotranspiration using a global data assimilation-forecasting system are discussed. NAL Call No.: 292.8-J82 ***************************************************************** 78. Impact of coal combustion waste on the microbiology of a model aquifer. Brunning, J. S.; Caldwell, D. E.; Lawrence, J. R.; Robarts, R. D. Water-air-soil-pollut v.74, p.103-120. (1994). Includes references. Descriptors: aquifers-; groundwater-; pollution-; fluidized-bed-wastes; coal-; combustion-; infiltration-; leaching-; landfills-; landfill-leachates; groundwater-; water-quality; alkalinity-; heterotrophic-microorganisms; bacteria-; bacterial-count NAL Call No.: TD172.W36 ***************************************************************** 79. The impact of recession infiltration on runoff volume computed by the kinematic wave model. Stone, J. J.; Shirley, E. D.; Lane, L. J. Trans-ASAE v.36, p.1353-1361. (1993). Includes references. Descriptors: runoff-water; infiltration-; rain-; kinematics-; modelsAbstract: The effect of recession infiltration on runoff volume is quantified using the kinematic wave modelfor the case of lateral inflow made up of constant rainfall excess during the period of rainfalland constant infiltration after rainfall ends. A general solution is obtained using thefollowing non-dimensional quantities; Q*=Q/R(e) (runoff volume divided by rainfall excess volume),t* = t(e)/D (time to kinematic equilibrium divided by the duration of rainfall excess), and f* = f/r(e) (infiltration rate divided by rainfall excess rate). Using these quantities, therelationship for the reduction of runoff volume is Q* =1-m/(m+1) t* [f*/(f*+1)](l/m) when t* < [(f*+])/f*]/(l/m) and Q* = 1/(m+1) t*1(-m) (f*+1)/f* when t* > [(f*+1)/f*](l/m) where m is thekinematic wave depth-discharge exponent. The first equation corresponds to the case when flow ceases after the characteristic from distance and time zero, C(0,0), reaches the end of the plane.The second equation corresponds to the case when the flow ceases and C(0,0) does not reach theend of the plane. These equations approximate the reduction of runoff volume for the more generalcase of time varying rainfall excess under constant and variable rainfall as would be the casewhen the rainfall excess is generated using the Green-Ampt infiltration equation. NAL Call No.: 290.9-Am32T ***************************************************************** 80. Importance of soil and cropping systems in the development of regional water quality policies. Geleta, S.; Sabbagh, G. J.; Stone, J. F.; Elliott, R. L.; Mapp, H. P.; Bernardo, D. J.; Watkins, K. B. J-environ-qual v.23, p.36-42. (1994). Technical Reports from the Symposium, "Minimizing Agricultural Nonpoint-Source Impacts", November 2, 1992, Minneapolis, Minnesota. Descriptors: triticum-aestivum; sorghum-bicolor; zea-mays; cropping-systems; soil-types; crop-yield; nitrate-nitrogen; leaching-; water-quality; irrigation-; simulation-models; geographical-information-systems; oklahomaAbstract: Targeting certain soils and cropping systems may be necessary in consideration of regional water quality protection policies. However, little information is available relating soils and cropping practices to regional water quality problems. This study evaluates crop yield and NO3-N movement to surface and groundwater on four soils and nine principal cropping systems in the High Plains region of Oklahoma. The cropping systems involve wheat (Triticum aestivum L.), grain sorghum [Sorghum bicolor (L.) Moench], and corn (Zea mays L.), and are part of a regional data base also containing soils and chemical management information. For each combination of crop, soil, cropping system, and chemical alternative, a 20-yr simulation was made. The simulation was based on a modeling system that includes EPIC-PST (crop growth/chemical movement model) interfaced with a Geographic Information System (GIS), Earthone. Results of each simulation included crop yield and NO3-N movement in runoff and percolation. Results show wide variations in NO3-N losses for different soils, irrigation systems, and cropping systems. When compared with continuous irrigated wheat and grain sorghum cropping systems, double-cropped wheat-grain sorghum resulted in greater NO3-N loss in percolation. Compared with sprinkler and LEPA (low energy precision application) irrigation systems, furrow irrigation resulted in high NO3-N loss on both fine-textured and coarse-textured soils, with significantly greater loss on the coarser-textured soils. The modeling framework can be used to compare alternative water quality policies. Broad policies such as a restriction on the amount of N that can be applied per hectare can be compared with targeted. coarser soils or under furrow irrigation. NAL Call No.: QH540.J6 ***************************************************************** 81. Infiltration and redistribution of organic liquids in layered porous media. Cary, J. W.; Simmons, C. S.; McBride, J. F. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. May/June 1994. v. 58 (3) p. 704-711. Includes references. Descriptors: porous-media; oils-; transport-processes; infiltration-; redistribution-; mathematical-models; vaclose-zone Abstract: The remediation of many toxic waste sites throughout the world requires a better understanding of the flow of organic liquids in the vadose zone. The infiltration and redistribution of three water-immiscible oils into columns filled with porous material containing different textural layers are reported. In some experiments, oil followed water into the columns and in others, water followed oil. An explicit, one-dimensional, multiphase flow code was used to model the results. The numerical model contains elements of code that: (i) mimic the Haines jump phenomenon in dry sand, (ii) account for oil entrapment when water infiltrates, (iii) include forces on the oil phase caused by surface-spreading pressures at the oil front in water-wetted pores, (iv) include forces on the oil phase caused by water intrusion into hydrophilic oil-saturated pores, and (v) generate a factor that matches the water potentials of textural layers for the initial boundary conditions. In general, the model did a reasonable job of predicting the distribution of both water and oil 8 h after infiltration was started, though some unresolved problems persist. The liquid potential matching factor and the hydrophobicity of the mineral particles induced by a transmission oil have practical applications. The matching factor may be easily adapted to all codes that model flow through layers. The in situ creation of hydrophobic mineral particles may prove useful for containing immiscible organic liquids that leak into the vadose zone. NAL Call No.: 56.9-So3 ***************************************************************** 82. Influence of amount and method of irrigation water application on leaching of atrazine. Troiano, J.; Garretson, C.; Krauter, C.; Brownell, J.; Huston, J. J-environ-qual v.22, p.290-298. (1993). Includes references. Descriptors: atrazine-; leaching-; percolation-; irrigation-; soil-water-content; spatial-distribution; sandy-soils; simulation-models; california-; leachm-model Abstract: A study was conducted to relate leaching of an herbicide, atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-di amine], and inorganic water tracers, Brand Cl-, to the amount of deep-percolating water produced from irrigation. Soil at the site was classified as a Dehli Loamy Sand (Mixed, Thermic, Tepic Xeropsamment) which was an unstructured sandy soil that was low in organic C content, conditions conducive to solute leaching. The relationship between depth of solute movement and amount of deep-percolating water was measured in sprinkler, basin, and furrow irrigation methods. Soil distribution of inorganic tracers indicated that graded levels of added water treatments, which were based on reference evapotranspiration, produced corresponding increases in the depth of percolated water. Atrazine's soil distribution indicated greater downward movement in response to increases in amount of deep-percolating water. Magnitude of leaching differed between irrigation methods and increased in the order: sprinkler < basin < furrow. Simulations using the LEACHM model provided a physically based explanation for the differences in water movement between sprinkler and basin methods. The total amount of applied water was similar at each level of percolation but sprinkler irrigations were more frequent, resulting in more evaporation and, consequently, less water available for deep percolation. Both amount and method of water application are important factors that determine pesticide movement and that, in irrigated agriculture, must be considered as integral components of pesticide management. NAL Call No.: QH540.J6 ***************************************************************** 83. The influence of variable precipitation patterns on simulations of pesticide mobility. Roth, G.; Stahl, G.; Iwan, J. Pestic-sci v.38, p.341-346. (1993). Includes references. Descriptors: pesticides-; leaching-; precipitation-; variation-; temperature-; frequency-distribution; weather-data; monte-carlo-method; simulation-models Abstract: The behaviour of pesticides in the soil is governed by a variety of complex processes including theclimatic conditions. To investigate the influence of these specific factors, a Monte-Carlo Methodwas used to generate sequences of daily precipitation and temperature data representing natural weather behaviour. Simulations of the leaching process were performed for different compounds withthese sequences while all other environmental parameters were held constant. The results indicatedthat the use of stochastic variables yields new insight into the leaching process. It is shownthat the naturally occurring variability of the weather pattern has a crucial influence on theleaching of pesticides. NAL Call No.: SB951.P47 ***************************************************************** 84. Integrated flux model for unsteady transport of trace organic chemicals in soils. Moldrup, P.; Poulsen, T. G.; Rolston, D. E.; Yamaguchi, T.; Hansen, J. A. Soil-sci v.157, p.137-152. (1994). Includes references. Descriptors: organic-compounds; transport-processes; movement-in-soil; drained-conditions; deterministic-models; unsaturated-soils; vadose-zone; relative-impact-of-chemicals-at-transient-state-riocats NAL Call No.: 56.8-So3 ***************************************************************** 85. Integrating water quality modeling with ecological risk assessment for nonpoint source pollution control: a conceptual framework. Chen, Y. D.; McCutcheon, S. C.; Rasmussen, T. C.; Nutter, W. L.; Carsel, R. F. Water-sci-technol v.28, p.431-440. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: water-quality; protection-; pollution-control; ecology-; risk-; assessment-; models-; usa-; best-management-practices NAL Call No.: TD420.A1P7 ***************************************************************** 86. Integration of geographic information systems and a computer model to evaluate impacts of agricultural runoff on water quality. He, C.; Riggs, J. F.; Kang, Y. T. Water-resour-bull v.29, p.891-900. (1993). Includes references. Descriptors: runoff-; river-water; water-pollution; water-quality; nitrogen-; phosphorus-; simulation-models; geographical-information-systems; michigan-; geographic-resource-analysis-support-system-grass; grass-waterworks; agricultural-nonpoint-source-pollution-model-agnps; cass-river; saginaw-bay; best-management-practices Abstract: This study integrates an Agricultural Non-Point Source Pollution Model (AGNPS), the Geographic Resource Analysis Support System (GRASS) (U.S. Army Corps of Engineers, 1987), and GRASS WATERWORKS (a hydrologic modeling tool box being developed at the Michigan State University Center for Remote Sensing) to evaluate the impact of agricultural runoff on water quality in the Cass River, a subwatershed of Saginaw Bay. AGNPS is used to estimate the amounts, origin, and distribution of sediment, nitrogen (N), and phosphorus (P) in the watershed. GRASS and GRASS WATERWORKS are used to generate parameters needed for AGNPS from digital maps, which include soil association, land use, watershed boundaries, water features, and digital elevation. Outputs of the model include spatially distributed estimates of volume and peak runoff, overland and channel erosion, sediment yields, and concentrations of nitrogen and phosphorus. Management scenarios are explored in the AGNPS model to minimize sedimentation and nutrient loading. Scenarios evaluated include variations in crop cover, tillage methods, and other agricultural management practices. In addition, areas vulnerable to erosion are identified for best management practices. NAL Call No.: 292.9-Am34 ***************************************************************** 87. Interfacial tension-induced transport of nonaqueous phase liquids in model aquifer systems. Anderson, M. A. Water-air-soil-pollut v.75, p.51-60. (1994). Includes references. Descriptors: soil-pollution; groundwater-; pollution-; solvents-; fuels-; transport-processes; immiscible-displacement; surface-tension; toluene-; sandNAL Call No.: TD172.W36 ***************************************************************** 88. Investigating prediction capability of HEC-1 and KINEROS kinematic wave runoff models. Obiukwu Duru, J.; Hjelmfelt, A. T. Jr. J-hydrol v.157, p.87-103. (1994). Includes references. Descriptors: watersheds-; rain-; storms-; runoff-; catchment-hydrology; prediction-; simulation-models Abstract: In this study, two distributed parameter, physically based, kinematic wave hydrologic models, HEC-1 and KINEROS, were tested on a 30.4 ha watershed located near Treynor, Iowa. The study had two objectives: (1) to determine the ability of the models to predict runoff with very limited calibration: (2) to determine how accurately the models can simulate runoff given accurate model parameters. The results show that HEC-1 can achieve good prediction of runoff with very limited calibration. It was not, however, possible to achieve the same level of prediction with the KINEROS model. Given good calibration, both models can simulate the rainfall runoff process with great accuracy. NAL Call No.: 292.8-J82 ***************************************************************** 89. Lake water quality modeling for projected future climate scenarios. Stefan, H. G.; Hondzo, M.; Fang, X. J-environ-qual v.22, p.417-431. (1993). Paper presented at the USDA-ARS Beltsville Agricultural Research Center Symposium XVII, "Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources," May 4-8, 1992, Beltsville, MD. Descriptors: lakes-; water-reservoirs; global-warming; carbon-dioxide; temperature-; dissolved-oxygen; size-; depth-; turbidity-; phytoplankton-; seasonal-variation; water-quality; simulation-models; water-temperature; trophic-status Abstract: A deterministic, one-dimensional numerical simulation model for water temperature and dissolved oxygen (DO) in lakes of different size, depth, and trophic status has been formulated, validated, and applied to lakes in the north central USA. The standard error of predictions is on the order of 1 degree C for temperature and 1.5 mg L(-1) for DO. The model is driven by weather measurements at off-lake weather stations. Simulations can be made for the open water season at daily timesteps and for as many years as weather data are available without any parameter adjustments. The model has been used to simulate the effect of climate change due to a doubling of atmospheric CO2 on water temperatures and DO in 27 lake classes in Minnesota. The lakes have been differentiated by surface area, maximum depth, and trophic status. Maximum water temperature near the surface is projected to increase by no more than 2 degrees C in midsummer, and DO will drop by less than 2 mg L(-1) in the surface waters but will remain above 7 mg L(-1). In contrast, hypolimnetic water temperature in midsummer may rise by as much as 4 degrees C or may become colder by as much as 4 degrees C. Hypolimnetic DO will be lower by as much as 8 mg L(-1) in midsummer and DO depletion is projected to occur for a longer period of time in midsummer in lakes with seasonal summer stratification. Changes will be largest in spring and fall because the summer stratification season will lengthen by 20 to 90 d for different lake types. NAL Call No.: QH540.J6 ***************************************************************** 90. Leachate geochemistry at a municipal landfill, Memphis, Tennessee. Mirecki, J. E.; Parks, W. S. Ground-water. Dublin, Ohio : Ground Water Pub. Co. May/June 1994. v. 32 (3) p. 390-398. Includes references. Descriptors: landfill-leachates; municipal-refuse-disposal; wells-; groundwater-; samples-; chemical-composition; concentration-; alluvium-; aquifers-; geochemistry-; models-; groundwater-pollution; tennesseeNAL Call No.: TD403.G7 ***************************************************************** 91. Long-term (15 years) results of NPS controls in an agricultural watershed upon a receiving lake's water quality. Garrison, P. J.; Asplund, T. R. Water-sci-technol v.28, p.441-449. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: watersheds-; agricultural-land; runoff-water; sediment-; nutrients-; prediction-; models-; pollution-control; phosphorus-; loads-; lakes-; water-quality; wisconsinNAL Call No.: TD420.A1P7 ***************************************************************** 92. Measuring and modeling root water uptake based on 36chloride discrimination in a silt loam soil affected by groundwater. Schmidhalter, U.; Selim, H. M.; Oertli, J. J. Soil-sci v.158, p.97-105. (1994). Includes references. Descriptors: daucus-carota; roots-; water-uptake; measurement-; salinization-; groundwater-; saline-water; capillary-rise; water-table; soil-depth; models-; solutes-; transport-processes; chloride-; soil-water-content NAL Call No.: 56.8-So3 ***************************************************************** 93. Miscible displacement and theoretical techniques for simultaneous study of pesticide sorption and degradation during transport. Gamerdinger, A. P.; Dowling, K. C.; Lemley, A. T. SSSA-spec-publ p.115-123. (1993). In the series analytic: Sorption and degradation of pesticides and organic chemicals in soil / edited by D.M. Linn, T.H. Carski, M.L. Brusseau and F.H. Chang. chemicals in soils," held on October 30, 1991, Denver, Colorado. Descriptors: pesticides-; transport-processes; models-; transformation-; sorption-; estimation-; techniquesNAL Call No.: S590.S62 ***************************************************************** 94. Model farms results reviewed as project nears an end. Carver, N. Inside-edge v.3, p.1-2. (1993). Descriptors: water-quality; farms-; models-; residues-; project-appraisal; iowaNAL Call No.: S561.6.I8I572 ***************************************************************** 95. Model of integrated effects of boron, inert salt, and water flow on crop yield. Shani, U.; Hanks, R. J. Agron-j v.85, p.713-717. (1993). Includes references. Descriptors: hordeum-vulgare; zea-mays; growth-models; mathematical-models; equations-; phytotoxicity-; boron-; salts-in-soil; soil-salinity; soil-water; water-flow; transport-processes; leaching-; available-water; crop-yield; yield-losses; simulation-models; utahAbstract: High boron concentration in the soil causes yield reduction. Recently, a piecewise linear response curve was applied to describe yield response to B in near steady-state conditions. However, application of similar curves to field situations where water, B, and other ion contents are transient and nonhomogeneous is limited. The objective of this study was to develop a model for simulation of the integrated effects of B, inert salt, and water on crop yield under field conditions. The model computes water flow in response to irrigation, rain, or evapotranspiration processes and subsequently computes inert salt and B transport. Crop yield is related to soil matric and osmotic potentials and B toxicity. Effects of B toxicity are considered by adapting the steady-state approach to the transient situation. Field experiments with barley (Hordeum vulgare L.) and corn (Zea mays L.) were conducted on the Utah Power & Light Co. research farm (Huntington, UT). Soil was Penoyer loam [coarse-silty, mixed (calcareous), mesic Typic Torriorthent]. Line source irrigation was used to obtain different irrigation levels. The effects of B, Salt mixture of Na, Ca, Cl, and SO4), and B + Salt on yield were studied in barley. The effect of B + Salt was studied also in corn. Measurements and simulations were in close agreement for both crops. Barley yield ranked B + Salt < B < Salt < control. Corn yield ranked B + Salt < control. The B adsorption properties result in less leaching than do those of an inert ion like Cl. The effects of initial and boundary conditions together with the B adsorption characteristics on B concentration in the soil solution and the subsequent yield reduction are presented. This model can serve for an analysis of the long-term effects of high B and help in understanding the relative. NAL Call No.: 4-AM34P ***************************************************************** 96. A model of nitrate leaching from agricultural systems in Virginia's Northern Neck. Johnson, T. G.; Parker, J. C. Blacksburg : Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1993. xviii, 308 p.. Includes bibliographical references (p. 125-137). TD201.V57--no.179 ***************************************************************** 97. Model simulations of dissolved oxygen characteristics of Minnesota Stefan, H. G.; Fang, X. Environ-manage. New York, Springer-Verlag. Jan/Feb 1994. v. 18 (1) p. 73-92. Includes references. Descriptors: lakes-; water-quality; dissolved-oxygen; simulation-models; climatic-change; minnesotaNAL Call No.: HC79.E5E5 ***************************************************************** 98. A modeling approach to evaluate best management practices. Williams, R. D.; Nicks, A. D. Water-sci-technol v.28, p.675-678. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: agricultural-land; crops-; river-water; water-pollution; protection-; soil-management; water-quality; improvement-; models-; usa-; vegetative-filter-strips NAL Call No.: TD420.A1P7 ***************************************************************** 99. Modeling mined land reclamation strategies in a GIS environment. Younos, T. M.; Yagow, E. R.; Zipper, C. E.; Diplas, P. Appl-eng-agric v.9, p.61-68. (1993). Includes references. Descriptors: mined-land; reclamation-; computer-software; models-; erosion-control; environmental-impact; virginiaAbstract: The erosion potential from mined lands is considered a major environmental threat. Mathematical models can be used to predict and demonstrate the effectiveness of various reclamation strategies for reducing erosion potential. The objective of this project was to use the Universal Soil Loss Equation (USLE) with a sediment yield component to evaluate the comparative effects of alternative reclamation strategies in a Geographic Information System (GIS) environment. The study site was an abandoned mined land (AML) site located in southwest Virginia. Topographic and landuse information for the site were obtained from topographic maps, aerial photographs, and field observation. The GIS tools were used to create digital data layers, store, analyze, and display information. The USLE factors were spatially derived from elevation, landuse, surface-water system, and watershed boundary data layers. The basic and derived data layers were then used to estimate the magnitude of soil loss and sediment yield. The methodology was used to predict the soil loss and sediment yield at the existing AML site, and to compare the effectiveness of three reclamation options for reducing soil loss and sediment yields. Results demonstrate the usefulness of the GIS tools for planning land reclamation strategies. NAL Call No.: S671.A66 ***************************************************************** 100. Modeling mobility and effects of contaminants in wetlands. Dixon, K. R.; Florian, J. D. Jr. Environ-toxicol-chem v.12, p.2281-2292. (1993). Annual Review Issue: Wetland Ecotoxicology and Chemistry. Descriptors: wetlands-; simulation-models; contaminants-; pollutants-; transport-processes; literature-reviews NAL Call No.: QH545.A1E58 ***************************************************************** 101. Modeling subsurface drainage and surface runoff with WEPP. Savabi, M. R. J-irrig-drain-eng v.119, p.801-813. (1993). Includes references. Descriptors: subsurface-drainage; surface-drainage; erosion-; erosion-control; models-; water-erosion-prediction-project NAL Call No.: 290.9-AM3Ps-IR ***************************************************************** 102. Modeling the effects of salt-water intrusion dynamics for a coastal karstified block connected to a detrital aquifer. Calvache, M. L.; Pulido Bosch, A. Ground-water. Dublin, Ohio : Ground Water Pub. Co. Sept/Oct 1994. v. 32 (5) p. 767-777. Includes references. Descriptors: aquifers-; coastal-areas; saline-water; contamination-; groundwater-flow; landforms-; simulation-models; mathematical-models; water-quality; salinization-; groundwater-pollution; spainNAL Call No.: TD403.G7 ***************************************************************** 103. Modeling the transport of solutes to groundwater using transfer functions. Roth, K.; Jury, W. A. J-environ-qual v.22, p.487-493. (1993). Paper presented at the USDA-ARS Beltsville Agricultural Research Center Symposium XVII, "Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources," May 4-8, 1992, Beltsville, MD. Descriptors: solutes-; transport-processes; chemicals-; unsaturated-flow; groundwater-; mathematical-models Abstract: Transport of chemicals through the unsaturated zone into groundwater is in general a highly nonlinear process with a pronounced spatial structure of which only a very limited number of measurements is economically and technically feasible. In most applications, it is thus not practicable to model these processes with high spatial and temporal resolutions. However, in an agricultural environment chemicals are usually applied to large areas, and we are generally interested in their long-term effects on groundwater quality. With these restrictions, the transport processes may be averaged in space and time over sufficiently large regions such that it may be permissible to use a stationary, linear approximation. An efficient way to study such systems exploits that a stationary, linear system is completely determined by its transfer function, that is, by its response to a narrow pulse input. We use a general formalism to represent the transport processes implicitly by the relation between the flux and the resident concentration of a conservative chemical. To model the transport of nonconservative chemicals, this description is coupled, as it was done by (Villermaux, 1981), with a model of the local interactions. We obtain an expression for the transfer function of a linearly adsorbing chemical with linear adsorption kinetics and first-order decay in the water and in the adsorbed phase which is based on the measured transfer function of a conservative tracer. This procedure has the major advantage that parameter estimation and model validation tests can be applied to the chemical reaction processes alone. KEEP. NAL Call No.: QH540.J6 ***************************************************************** 104. Movement of nitrogen through and agricultural riparian zone. 2. Distributed modeling. Nikolaidis, N. P.; Shen, H.; Heng, H.; Hu, H. L.; Clausen, J. C. Water-sci-technol v.28, p.613-623. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: riparian-forests; pollutants-; sources-; nitrogen-; groundwater-pollution; surface-water; water-pollution; movement-in-soil; mathematical-models; connecticutNAL Call No.: TD420.A1P7 ***************************************************************** 105. New models for unsaturated soil hydraulic properties. Zhang, R.; Genuchten, M. T. v. Soil-sci v.158, p.77-85. (1994). Includes references. Descriptors: soil-water-retention; unsaturated-hydraulic-conductivity; mathematical-models; solutes-; transport-processes; water-flow NAL Call No.: 56.8-So3 ***************************************************************** 106. NLEAP simulation of residual soil nitrate for irrigated and nonirrigated corn. Follett, R. F.; Shaffer, M. J.; Brodahl, M. K.; Reichman, G. A. J-soil-water-conserv v.49, p.375-382. (1994). Commentary. Descriptors: zea-mays; sandy-soils; irrigated-conditions; soil-water-regimes; nitrogen-fertilizers; application-rates; nitrate-; residues-; leaching-; nitrogen-; nutrient-uptake; precipitation-; seasonal-variation; simulation-models; crop-yield; nitrate-leaching-and-economic-analysis-package; nutrient-management NAL Call No.: 56.8-J822 ***************************************************************** 107. Nondestructive determination of hydrogeometrical characteristics of soil macropores. Wang, D.; Norman, J. M.; Lowery, B.; McSweeney, K. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. Mar/Apr 1994. v. 58 (2) p. 294-303. Includes references. Descriptors: macropores-; characterization-; nondestructive-testing; dimensions-; water-flow; macropore-flow; transport-processes; mathematical-models Abstract: Hydrological and geometrical parameters of macropores are essential for modeling water and solute transport through soils containing macropores. This study was conducted to develop a fast and nondestructive technique for determining the hydrological and geometrical characteristics of soil macropores. We measured the rate of water flowing into ant and earthworm burrows with a macropore infiltrometer and estimated burrow diameter, volume, and depth from the measured flow rate and a water flow model. To evaluate the estimated burrow parameters, we made castings of the ant and earthworm burrows with a dental plaster. The burrows had similar diameters (2.1 mm for laminar flow; 2.9 mm for turbulent flow) but different volumes and depths [281-cm(3) volume and 0.60-m depth for ant burrows; 210-cm(3) volume and 0.82-m depth for earthworm burrows]. This technique is reasonable for ant burrows because the root mean square difference (RMSD) between casting and infiltrometer-calculated volumes is 17%; however, errors are larger for earthworm burrows (RMSD is 73%). Saturated soil matrix hydraulic conductivity [K(s)] estimated from the infiltrometer measurement of earthworm burrows were comparable to matrix K(s) of the bulk silt loam. The matrix K(s) values estimated for ant burrows were about eight times smaller than matrix K(s) of the bulk sandy soil. Such large decrease in K(s) is probably caused by infilling of burrow walls by ants with fine materials. Combining the macropore infiltrometer measurements with the model is a useful means of estimating the hydrological and geometrical parameters of ant and possibly earthworm burrows. NAL Call No.: 56.9-So3 ***************************************************************** 108. Nonpoint source (NPS) pollution modeling using models integrated with geographic information systems (GIS). Engel, B. A.; Srinivasan, R.; Arnold, J.; Rewerts, C.; Brown, S. J. Water-sci-technol v.28, p.685-690. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: pollution-; sources-; watersheds-; rain-; agricultural-chemicals; runoff-water; water-pollution; water-erosion; geographical-information-systems; models-; usa-; chemicals,-runoff,-and-erosion-from-agricultural-managementsystems NAL Call No.: TD420.A1P7 ***************************************************************** 109. Nonpoint sources. Line, D. E.; Osmond, D. L.; Coffey, S. W.; Arnold, J. A.; Gale, J. A.; Spooner, J.; Jennings, G. D. Water-environ-res v.66, p.585-601. (1994). Includes references. Descriptors: water-pollution; soil-pollution; water-quality; water-resources; pollutants-; pesticides-; biodegradation-; pollution-control; models-; monitoring-; literature-reviews NAL Call No.: TD419.R47 ***************************************************************** 110. Numerical approach to the overland flow process in vegetative filter strips. Munoz Carpena, R.; Parsons, J. E.; Gilliam, J. W. Trans-ASAE v.36, p.761-770. (1993). Includes references. Descriptors: erosion-control; overland-flow; pollution-control; runoff-; sediment-; shelterbelts-; simulation-models; water-pollution; mathematical-models; north-carolina Abstract: Agricultural and other disturbed lands contribute to non-point source pollution of water bodies (streams and lakes). Vegetative filter strips (VFS) are often recommended to reduce off-site impacts. Design guidelines to optimize performance of VFS are not readily available. A process-based model is presented to simulate the hydrology of a Vegetative Filter Strip for a given event. The model consists of a quadratic finite element overland flow submodel, based on the kinematic wave approximation, coupled with an infiltration submodel based on a modification of the Green-Ampt equation for unsteady rainfall. The model is used to study the effect of soil type, stope, surface roughness, buffer length, storm pattern and field inflow on the VFS performance. Filter performance, i.e., reduction of the runoff volume, velocity and peak, is higher for denser grass cover, smaller slopes and soils with higher infiltration capacity. Time to peak(s) depended mainly on the roughness-slope combination. NAL Call No.: 290.9-Am32T ***************************************************************** 111. Observed and simulated transport of a conservative tracer under line-source irrigation. Comfort, S. D.; Inskeep, W. P.; Lockerman, R. H. J-environ-qual v.22, p.554-561. (1993). Paper presented at the USDA-ARS Beltsville Agricultural Research Center Symposium XVII, "Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources," May 4-8, 1992, Beltsville, MD. Descriptors: solutes-; transport-processes; soil-water-regimes; irrigation-; soil-depth; simulation-models; agricultural-chemicals; silt-loam-soils; montana-; vadose-zone; leachm-simulation-model Abstract: Although a number of solute transport models are currently available to predict the transport of agrichemicals in the vadose zone, validation of these models under field conditions has been limited. This study monitored the transport of a conservative tracer (Br-) under three water regimes (high, medium, and low) imposed by a line-source irrigation system and tested the validity of the simulation model, LEACHM, to predict Brtransport. In July 1990, RbBr was surface applied to 12 uncropped columns at 56 kg Brha(-1). Four columns (0.203-m diam., 1.2-m length) were positioned in each water regime and equipped with soil solution samplers at .36-, 0.66-, and 0.96-m depths. Soil solution samples were taken 20 times over 80 d to monitor Brtransport. Cumulative water applied to each water regime, by irrigation and precipitation, ranged between 251 and 458 mm. Results indicated dramatic differences in Brtransport among water regimes. Complete Brbreakthrough curves (with apex concentrations of approximately 60 mg BrL(-1) were observed under high water regime at all depths whereas the majority of Brapplied to the low water regime remained at or near the 0.36-m depth. Inputs used to predict Brtransport in LEACHM simulations were either measured directly or estimated from experimental conditions. To simulate Brtransport for each water regime, we used three LEACHM input files, which reflected the variability of the soil profile water release retention coefficients. Results indicated that LEACHM's predictions of Brconcentration (at all depths and under all water regimes) differed from observed means by an average (n = 180) of 9.0 to 9.4 mg BrL(-1) (approximately 15-16% of the average apex concentrations). These results indicate that under the experimental system studied, LEACHM. vadose zone. NAL Call No.: QH540.J6 ***************************************************************** 112. One-dimensional infiltration with moving finite elements and improved soil water diffusivity. Cox, C. L.; Jones, W. F.; Quisenberry, V. L.; Yo, F. Water-resour-res v.30, p.1431-1438. (1994). Includes references. Descriptors: soil-water; solutes-; diffusivity-; infiltration-; transport-processes; mathematical-models; transport-models Abstract: A problem of significant interest to environmental scientists is the flow of water and solutes through the vadose zone. The partial differential equations which govern this flow are typically time-dependent and nonlinear. Valid solutions to these equations require (1) accurate relationships between various coefficients and variables on which they depend (e.g., coefficient of diffusivity and water content) and (2) sophisticated numerical methods which can handle complexities such as sharp moving fronts. In cases where coefficients are not known explicitly, curve-fitting techniques are needed to smooth out scattered experimental data. Nonlinear coefficients can then be calculated. A constrained least squares spline fit is compared to empirical function fits which have appeared recently. Then, a state-of-the-art numerical technique is used to accurately model transient flow through unsaturated homogeneous soils. The moving finite element method of Miller and colleagues is an adaptive approach in the sense that the grid moves so that nodes are concentrated where they are most needed. As a result, better accuracy is achieved with fewer nodes than are required for standard fixed-grid methods. Petzold's robust Gear-type solver DASSL is used for time-integration. Numerical results are compared to experimental data. Mass balance errors are negligible, and accurate solutions are obtained at all time steps. Though only one-dimensional problems are considered here, the numerical approach generalizes to heterogeneous media and problems in higher dimensions. NAL Call No.: 292.8-W295 ***************************************************************** 113. Outdoor testing of the condensation characteristics of plastic film covering materials using a model greenhouse. Geoola, F.; Peiper, U. M.; Geoola, F. J-agric-eng-res v.57, p.167-172. (1994). Includes references. Descriptors: greenhouses-; plastic-film; cladding-; field-tests; solar-radiation; light-transmission; condensation-; runoff-water; round-arch-greenhouses; transparency-loss; film-ageing NAL Call No.: 58.8-J82 ***************************************************************** 114. Parameter identification for a runoff model for forest roads. Luce, C. H.; Cundy, T. W. Water-resour-res v.30, p.1057-1069. (1994). Includes references. Descriptors: forests-; roads-; runoff-; erosion-; infiltration-; overland-flow; rain-; simulation-; algorithms-; idaho-; colorado-; montanaAbstract: Rainfall simulation is a commonly used approach for studying runoff and erosion from forest roads, and a method is needed to estimate infiltration parameters from these experiments. We used two algorithms, the Simplex and Shuffled Complex Evolution, to estimate parameters for a physically based infiltration and overland flow model. Each algorithm was tested by estimating parameters for 92 field-measured hydrographs from forest roads. Nine of the field-measured hydrographs allowed us to further test whether estimated parameters could be extended to other antecedent conditions and plot sizes. The results demonstrate (1) the physically based model is able to estimate hydrographs from forest roads, (2) the two algorithms find unique parameter sets in spite of an error surface that suggests identifiability problems between the hydraulic conductivity and pressure parameters, (3) the two algorithms converged to the same parameter values, and (4) that parameters estimated for one antecedent condition and plot size can be extended to others with reasonably mall error. NAL Call No.: 292.8-W295 ***************************************************************** 115. Pesticide leaching data to validate simulation models for registration purposes. Bergstrom, L.; Jarvis, N.; Stenstrom, J. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1073-1104. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: dichlorprop-; leaching-; sandy-soils; loam-soils; clay-soils; simulation-models; bentazoneNAL Call No.: TD172.J6 ***************************************************************** 116. Point/nonpoint source trading of pollution abatement: choosing the right trading ratio. Malik, A. S.; Letson, D.; Crutchfield, S. R. Am-j-agric-econ v.75, p.959-967. (1993). Includes references. Descriptors: pollution-control; law-enforcement; costs-; water-quality; trading-; uncertainty-; mathematical-models; ratios-; usa-; abatement-costs Abstract: In programs for trading pollution abatement between point and nonpoint sources, the trading ratiospecifies the rate at which nonpoint source abatement can be substituted for point sourceabatement. The appropriate value of this ratio is unclear because of qualitative differencesbetween the two classes of sources. To identify the optimal trading ratio, we develop and analyzea model of point/nonpoint trading. We find the optimal trading ratio depends on the relativecosts of enforcing point versus nonpoint reductions and on the uncertainty associated with nonpoint loadings. The uncertainty does not imply a lower bound for the optimal trading ratio. NAL Call No.: 280.8-J822 ***************************************************************** 117. Potassium and phosphorus uptake by competing pine and grass: observations and model verification. Smethurst, P. J.; Comerford, N. B. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. Nov/Dec 1993. v. 57 (6) p. 1602-1610. Includes references. Descriptors: pinus-elliottii; seedlings-; panicum-; plant-competition; interspecific-competition; potassium-; phosphorus-; nutrient-uptake; computer-simulation; simulation-models; root-systems; surface-area; transport-processes; soil-fertility; pinus-elliotii-var; -elliotii; panicum-aciculare Abstract: A computer model (COMP8) was recently presented that simulates nutrient uptake by competing andsingle root systems. However, the model needed independent verification. Our objectives here wereto: (i) determine if uptake by each species was a simple function of each species' root surface area, and (ii) verify COMP8 for K and P uptake by slash pine (Pinus elliottii Engelm. var.elliottii) seedlings in competition with Panicum aciculare Desv. ex Poir. in Lam. grass plants.Pine and grass plants were grown together at low and high initial soil-solution concentrations. Observed and predicted uptake values were compared by linear regression and by t tests using variances predicted by Monte Carlo analysis. For high initial solution conditions, wequantitatively predicted pine uptake for all cases of P and for three of four cases for K. Grass Kuptake was accurately predicted in all three cases; however, none of the three cases of grassuptake of P were correct. For the low initial solution concentrations, only one case of pine andno cases of grass uptake were predicted accurately. For neither K nor P was uptake by pine(expressed as a percentage of that taken up by pine and grass combined) in a 1:1 relationship withthe percentage of surface area in pine roots. We conclude that uptake by the competing rootsystems is not a simple function of their relative root surface areas and that COMP8 provides anadequate description of nutrient uptake by competing and contrasting root systems under certain. NAL Call No.: 56.9-So3 ***************************************************************** 118. A pragmatic field-scale approach for modeling pesticides. Hutson, J. L.; Wagenet, R. J. J-environ-qual v.22, p.494-499. (1993). Paper presented at the USDA-ARS Beltsville Agricultural Research Center Symposium XVII, "Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources," May 4-8, 1992, Beltsville, MD. Descriptors: pesticides-; leaching-; soil-water-movement; simulation-models Abstract: Environmental assessments of the fate of pesticides and other agricultural chemicals usually require estimation of chemical concentrations, with some indication of their accuracy. These estimations are usually based on a few measurements combined with existing data bases and predictive tools that include regression equations, empirical relationships, and simulation models. Comprehensive simulation models are attractive from a scientific standpoint, since they consider leaching of the chemical by water as well as the various chemical, biological, and physical processes that affect the chemical's fate during its transport. A number of simulation modeling approaches have been developed to describe soil-water-chemical systems, but a fundamental question remains regarding the degree of model complexity required to simulate agrochemical movement to groundwater. Most model complexity in soil-water-chemical simulation models arises from the manner in which water flow and chemical transport are considered. It is therefore logical, especially for management purposes, to consider alternative, pragmatic, and yet sufficiently accurate approaches to the description of water flow and chemical transport. Such approaches would require less characterization of soil hydraulic and physical/chemical properties and would reduce computation time. A method for such simplification and use is described, starting with LEACHP, a model based on the Richards and convection-dispersion equations. The resulting model is shown to be sufficiently accurate for many management decisions. NAL Call No.: QH540.J6 ***************************************************************** 119. Predicting attainable water quality using the ecoregional approach. Schonter, R.; Novotny, V. Water-sci-technol v.28, p.149-158. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: water-quality; body-water; protection-; integrated-systems; water-resources; water-management; ecosystems-; prediction-; models-; wisconsin-; integrated-water-resource-management; ecoregional-nonpoint-source-model NAL Call No.: TD420.A1P7 ***************************************************************** 120. Predicting bromide leaching under field conditions using slim and macro. Jabro, J. D.; Jemison, J. M. Jr.; Fox, R. H.; Fritton, D. D. Soil-sci v.157, p.215-223. (1994). Includes references. Descriptors: agricultural-chemicals; leaching-; movement-in-soil; macropore-flow; simulation-models; computer-simulation; groundwater-pollution; risk-; prediction-; preferential-flow NAL Call No.: 56.8-So3 ***************************************************************** 121. Predicting spatial distributions of nitrate leaching in northeastern Colorado. Wylie, B. K.; Shaffer, M. J.; Brodahl, M. K.; Dubois, D.; Wagner, D. G. J-soil-water-conserv v.49, p.288-293. (1994). Includes references. Descriptors: agricultural-land; nitrate-nitrogen; leaching-; spatial-distribution; groundwater-pollution; nitrate-; contamination-; prediction-; simulation-models; geographical-information-systems; point-sources; colorado-; non-point-source-pollution NAL Call No.: 56.8-J822 ***************************************************************** 122. Predicting water yield from a mountain ash forest catchment using a terrain analysis based catchment model. Vertessy, R. A.; Hatton, T. J.; O'Shaughnessy, P. J.; Jayasuriya, M. D. A. J-hydrol v.150, p.665-700. (1993). In the special issue: Water Issues in Forests Today / edited by E.M. O'Loughlin and F.X. Dunin. November 22-26, 1992, Canberra, Australia. Descriptors: mountain-forests; eucalyptus-regnans; water-yield; simulation-models; catchment-hydrology; evapotranspiration-; water-balance; soil-water; interception-; runoff-; stream-flow; australiaAbstract: The structure, capabilities and performance of a distributed parameter hydrologic model are described. The model, called Topog-Yield, permits a transient analysis of unsaturated-saturated flow and evapotranspiration to be performed across complex terrain using a one-dimensional framework. It is applied to a 0.32 km2 mountain ash (Eucalyptus regnans) forest catchment in the central Victorian highlands, Australia. We compare observed and predicted daily runoff values for the site over a continuous 12 year period (1972-1983) when the catchment vegetation was in an undisturbed climax condition. All input parameter values were based on published or measured data, although some variables were adjusted within the range of known variability to yield a best fit between predicted and observed streamflow in the first year of simulation, 1972. Although the model was 'calibrated' for the first year, all variables other than climatic inputs remained fixed for the following 11 years. Modelled and observed daily runoff values compare well throughout the period of simulation, despite a wide range of climatic conditions. When modelled daily runoff values were lumped on a monthly basis, the model was able to explain 87% of the variation in observed monthly streamflows over the 12 year period. Modelled annual runoff was within +/5% of observed values for 6 of the 12 years of record. Annual runoff prediction errors exceeded +/10% of observed values in only 2 of the 12 years. By the end of the 12 year simulation, the model had over-predicted runoff by less than 5%. Input data requirements and model results are discussed in the light of a preliminary sensitivity analysis. NAL Call No.: 292.8-J82 ***************************************************************** 123. Preferential transport of nitrate through soil columns containing root channels. Li, Y.; Ghodrati, M. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. May/June 1994. v. 58 (3) p. 653-659. Includes references. Descriptors: nitrate-; transport-processes; movement-in-soil; macropore-flow; root-channels; mathematical-models; comparisons-; preferential-flow Abstract: Preferential flow has been increasingly recognized as an important mechanism for water and solute transport. The objectives of this study were to characterize transport of through root channels in uniformly packed soil columns and to compare three commonly used solute transport models in describing NO3 transport through the soil-root channel columns. Root channels were created by growing corn (Zea mays L.) or alfalfa (Medicago sativa L.) in 0.6-m-long soil columns. Transport of Was then systematically studied with each of these macropore systems at a range of fluxes (from 0.042K(sm) to 0.47K(sm), where K(sm) is the saturated hydraulic conductivity of the macroporous system). A nonlinear least-squares program was used to fit the convection-dispersion equation (CDE), the physical nonequilibrium model (MIM) and a stochastic model (SM) to the experimental data. The results show that significant preferential movement of NO3 occurred in the decayed root channels at fluxes as low as 0.042K(sm). The MIM model provided a better description of the breakthrough curves than the CDE and the SM, while none of them were adequate to predict the preferential movement of the solute. NAL Call No.: 56.9-So3 ***************************************************************** 124. Proceedings of the Symposium on Geographic Information Systems and Water Resources. Harlin, J. M.; Lanfear, K. J.; Symposium on Geographic Information Systems and Water Resources (1993 : Mobile, A. Bethesda, Md. : American Water Resources Association, c1993. xvi, 640 p. : ill. (some col.), maps (some col.). Includes bibliographies and indexes. Descriptors: Geographic-information-systems; Water-supplyNAL Call No.: TC401.A5-no.93-1 ***************************************************************** 125. Progress in the understanding of runoff generation dynamics in forests. Bonell, M. J-hydrol v.150, p.217-275. (1993). In the special issue: Water Issues in Forests Today / edited by E.M. O'Loughlin and F.X. Dunin. November 22-26, 1992, Canberra, Australia. Descriptors: tropical-forests; runoff-; sloping-land; humid-tropics; hydrology-; research-; simulation-models; literature-reviews Abstract: This work reviews the runoff generation process in forests. A survey of the delivery mechanisms of hillslope runoff and the difficulties of incorporating some of them in recent physically based models is considered. The research challenge in reconciling the results from recent stream hydrogeochemistry studies with the results from previous hillslope hydrometric experiments is also highlighted. 'Physically based' runoff process models for application to forest land management problems are then summarised. The work concludes by proposing a new, intensive phase in experimental hydrology which should support the continued development of new algorithms in runoff process modelling. Particular attention should be given to tropical forests and the need for additional hillslope hydrology research to address the important issues associated with hillslope management and conversion. NAL Call No.: 292.8-J82 ***************************************************************** 126. A prototype shell for running field scale natural resource simulation models. Hernandez, M.; Heilman, P.; Lane, L. J.; Stone, J. J.; Abolt, J. A.; Masterson, J. E. II. Application of advanced information technologies effective management of natural resources proceedings of the 18-19 June 1993 Conference, Spokane, Washington /. St. Joseph, Mich. : American Society of Agricultural Engineers, c1993.. p. 142-149. Includes references. Descriptors: water-quality; decision-making; simulation-models; interface-; design-; usda-; usa-; agricultural-research-service NAL Call No.: GE5.A66-1993 ***************************************************************** 127. Quantifying soil erosion for the Shihmen Reservoir watershed, Taiwan. Lo, K. F. A. Agric-syst v.45, p.105-116. (1994). Includes references. Descriptors: watersheds-; erosion-; sediment-; nutrients-; flow-; transport-processes; sediment-yield; simulation-models; taiwan-; agnps-model-agricultural-non-point-source-pollution NAL Call No.: HD1.A3 ***************************************************************** 128. Real-time flood forecasting in mountainous river basins with longand short-term runoff model. Islam, M. N.; Nagai, A.; Yomota, A. J-irrig-eng-rural-plann p.48-66. (1994). Includes references. Descriptors: flooding-; runoff-; hydrological-data; filters-; simulation-; forecasting-; optimization-; models-; mountain-areas; comparisons-; japanNAL Call No.: S671.J68 ***************************************************************** 129. Regional scale ground water quality monitoring : methods and case studies. Hudak, P. F.; Loaiciga, H. A.; Marino, M. A.; California Water Resources Center. [Riverside, Calif.] : California Water Resources Center, 1993. xi, 74 p. : ill., maps. "April, 1993.". Descriptors: Water-quality-management-Mathematical-models; Water-quality-management-Methodology; Water-quality-management-Case-studies; Ground-water-Quality NAL Call No.: GB705.C2C676--no.203 ***************************************************************** 130. Regulation of nitrogen pollution in agriculture. Johnson, S. R. 1.; United States Israel Binational Agricultural Research and Development Fund. Bet Dagan, Israel : BARD, 1994. 223 leaves : ill.. Final report. Descriptors: Nitrogen-fertilizers-Control-Mathematical-models NAL Call No.: S651.R43--1994 ***************************************************************** 131. Removing numerically induced dispersion from finite difference models for solute and water transport in unsaturated soils. Moldrup, P.; Yamaguchi, T.; Rolston, D. E.; Vestergaard, K.; Hansen, J. A. Soil-sci v.157, p.153-161. (1994). Includes references. Descriptors: solutes-; soil-water; transport-processes; simulation-models; mathematical-models; calculation-; errors-; correction-factors; calculation-schemes NAL Call No.: 56.8-So3 ***************************************************************** 132. Risk versus economic return in managing groundwater nitrate contamination. Adelman, D. H.; Dahab, M. F. Water-sci-technol v.28, p.55-63. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: groundwater-pollution; nitrates-; farm-management; farming-; techniques-; prediction-; decision-making; models-; returns-; irrigated-farming; irrigation-water; utilization-; nitrogen-fertilizers; application-rates; nebraskaNAL Call No.: TD420.A1P7 ***************************************************************** 133. Root zone effects on tracer migration in arid zones. Tyler, S. W.; Walker, G. R. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. Jan/Feb 1994. v. 58 (1) p. 25-31. Paper presented at the Symposium on "Recharge in arid and semiarid regions," October 28-30, 1991, Denver, Colorado. Descriptors: groundwater-recharge; estimation-; soil-water; root-zone-flux; transport-processes; mathematical-models; arid-zones; tracer-techniques; errorsAbstract: The study of groundwater recharge and soil water movement in arid regions has received increased attention in the search for safe disposal sites for hazardous wastes. In passing through the upper 1 to 2 m of most soil profiles, tracers indicative of recharge such as Cl, 2H, 18O, Br, 3H, and 36Cl are subjected to a wide range of processes not encountered deeper in the profile. This transition zone, where water enters as precipitation and leaves as recharge, is often ignored when environmental tracers are used to estimate deep soil water flux and recharge, yet its effect may be profound. In this work, we reexamine the processes of root extraction and its effect on the velocity and distribution of tracers. Examples are presented for idealized conditions, which show clearly the relation between the root zone processes and the deep drainage or recharge. The results indicate that, when recharge is small and root zone processes are not accounted for, tracer techniques can significantly overestimate recharge until the tracer has moved well below the root zone. By incorporating simple models of root zone processes, a clearer understanding of tracer distributions and a more accurate estimate of recharge can then be made. NAL Call No.: 56.9-So3 ***************************************************************** 134. Runoff changes simulated using a rainfall-runoff model. Buchtele, J. Water-resour-manag v.7, p.273-287. (1993). Includes references. Descriptors: runoff-; change-; rivers-; rain-; watersheds-; simulation-models; climatic-change; czechoslovakiaAbstract: The Sacramento rainfall-runoff model has been used in experiments with 60 year daily series for the Czech part of the Labe River basin; simulations with decreased and/or increased inputs (precipitations, air temperature, evapotranspiration) provide results that could be used to appraise the runoff changes due to climatic warming. Simulations with the modified parameters are used for evaluation of runoff changes caused by land-use changes. For both purposes, the long-term data sets appear to be desirable; it is then possible to take into account 'accidental' influences. The simulations also provide, as an output, the water contents in different zones of soil moisture; the relationships among evapotranspiration, soil moisture, and baseflow clearly appear in these results. NAL Call No.: TC401.W27 ***************************************************************** 135. Runoff hydrograph estimation using artificial neural networks. Hjelmfelt, A. T. Jr.; Wang, M. Application of advanced information technologies effective management of natural resources proceedings of the 18-19 June 1993 Conference, Spokane, Washington /. St. Joseph, Mich. : American Society of Agricultural Engineers, c1993.. p. 315-320. Includes references. Descriptors: runoff-; rain-; hydrology-; models-; prediction-; algorithms-; simulation-models; missouri-; rainfall-runoff-models NAL Call No.: GE5.A66-1993 ***************************************************************** 136. RUSLE model description and database sensitivity. Renard, K. G.; Ferreira, V. A. J-environ-qual v.22, p.458-466. (1993). Paper presented at the USDA-ARS Beltsville Agricultural Research Center Symposium XVII, "Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources," May 4-8, 1992, Beltsville, MD. Descriptors: surface-water; water-quality; simulation-models; computer-software; revised-universal-soil-loss-equation-model Abstract: Water quality modeling generally requires estimates of the amount of eroded material entering water courses. This information is necessary because sediment often transports adsorbed chemicals. Numerous models have been developed to assist with assessment of this problem. These models often contain some modification of the Universal Soil Loss Equation (USLE). A recently initiated effort to improve USLE technology has produced a computer-based model, RUSLE (Revised USLE), which employs new relationships to estimate values of the six factors in the equation. Three input databases are NAL Call No.: QH540.J6 ***************************************************************** 137. Selection of herbicide alternatives based on probable leaching to groundwater. Franklin, R.; Quisenberry, V. L.; Gossett, B. J.; Murdock, E. C. Weed-technol v.8, p.6-16. (1994). Includes references. Descriptors: water-quality; groundwater-pollution; herbicides-; leaching-; weed-control; chemical-control; coastal-plain-soils; movement-in-soil; estimation-; persistence-; prediction-; mathematical-models; south-carolina NAL Call No.: SB610.W39 ***************************************************************** 138. A semi-analytical solution for one-dimensional solute transport in soils. Yamaguchi, T.; Moldrup, P.; Rolston, D. E.; Peterson, L. W. Soil-sci v.158, p.14-21. (1994). Includes references. Descriptors: solutes-; transport-processes; mathematical-models; moving-concentration-slope-models NAL Call No.: 56.8-So3 ***************************************************************** 139. Similarity analysis of runoff generation processes in real-world catchments. Larsen, J. E.; Sivapalan, M.; Coles, N. A.; Linnet, P. E. Water-resour-res v.30, p.1641-1652. (1994). Includes references. Descriptors: runoff-; watersheds-; agricultural-land; quantitative-analysis; prediction-; rain-; simulation-models; western-australia; rainfall-runoff-models; eastern-wheat-belt-of-western-australia Abstract: This paper addresses the question of similarity of runoff generation processes between catchments in the eastern wheat belt of Western Australia, and the use of dimensionless parameterizations to quantify this similarity. A spatially distributed rainfall-runoff model, simulating runoff generation by both the infiltration excess (Horton type) and saturation excess (Dunne type) mechanisms, was developed for catchments in the region. Seven small experimental catchments, with field-measured soil hydraulic properties and topography, were used in the study. Following on from the similarity theory developed by Sivapalan et al. (1987), a number of dimensionless similarity parameters were constructed using the field-measured soil and topographic properties, a characteristic length scale, and a characteristic flow velocity. The objective was to determine whether the dominant runoff generation mechanism on a catchment could be reliably predicted by these similarity parameters. This was achieved through sensitivity analyses carried out with the rainfall-runoff model. Two dimensionless parameters, K(*/0) and f*, were found to be critical for characterizing the similarity or dissimilarity of the runoff generation responses between the seven experimental catchments. Within the assumptions of the analysis, two catchments in the wheat belt region can be considered to be hydrologically similar, in terms of their runoff responses, if K(*/0) and f* are identical in both catchments. The dominant mechanism of runoff generation on any catchment can be reliably predicted, provided that the values of K(*/0) and f* are known. A partial quantification of the Dunne diagram. excess and saturation excess mechanisms, was achieved by artificially varying K(*/0) and f* in the rainfall-runoff model to explore the full range of possible runoff generation responses. NAL Call No.: 292.8-W295 ***************************************************************** 140. A simple energy budget algorithm for the snowmelt runoff model. Kustas, W. P.; Rango, A.; Uijlenhoet, R. Water-resour-res v.30, p.1515-1527. (1994). Includes references. Descriptors: runoff-; meltwater-; energy-balance; solar-radiation; algorithms-; prediction-; simulation-models Abstract: The snowmelt runoff model (SRM) uses a degree-day approach for melting snow in a basin. A simple radiation component was combined with the degree-day approach (restricted degree-day method) in an effort to improve estimates of snowmelt and reduce the need to adjust the melt factor over the ablation season. A daily energy balance model was formulated that requires not only the input of radiation but also measurements of daily wind speed, air temperature, and relative humidity. The three approaches for computing snowmelt, namely, the degree-day, restricted degree-day, and daily energy balance model were tested at the local scale by comparing melt rates with lysimeter outflow measurements. Because radiation measurements are not often available, a simple model for simulating shortwave and longwave components of the radiation balance that requires minimal information (i.e., daily cloud cover estimates, air temperature, and relative humidity) was developed. It was found that clouds and their effects on daily insolation at the surface can produce significant differences between measured and model estimates. In the comparisons of snowmelt estimates with the lysimeter outflow, the restricted degree-day method yielded melt rates that were in better agreement with the observed outflow than the degree-day method and were practically the same as estimates given by the energy balance model. A sensitivity analysis of runoff generated with SRM using as input the local snowmelt computations given by the three models and measured outflow from the lysimeter was performed for a basin. A comparison of the synthetic hydrographs for the basin suggests that a radiation-based snowmelt factor may improve runoff predictions at the basin scale. NAL Call No.: 292.8-W295 ***************************************************************** 141. Simulating acidification and recovery processes in experimental catchments with the ILWAS model. Eary, L. E.; Jenne, E. A.; Vail, L. W. Water-air-soil-pollut v.74, p.29-63. (1994). Includes references. Descriptors: acid-deposition; acidification-; watersheds-; soil-chemistry; simulation-models; mathematical-models; discharge-; cations-; ion-exchange; surface-water; water-quality; cation-exchange-capacity; norway-; base-cations; deacidificationNAL Call No.: TD172.W36 ***************************************************************** 142. Simulating funnel-type preferential flow and overall flow property induced by multiple soil layers. Ju, S. H.; Kung, K. J. S. J-environ-qual v.22, p.432-442. (1993). Paper presented at the USDA-ARS Beltsville Agricultural Research Center Symposium XVII, "Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources," May 4-8, 1992, Beltsville, MD. Descriptors: sandy-soils; soil-water-movement; unsaturated-flow; transport-processes; mathematical-models; simulation-models Abstract: Funnel-type preferential flow was observed in Plainfield sand (sandy, mixed, mesic Typic Udipsamment) of central Wisconsin. The objective of this paper was (i) to develop a numerical model based on the Rich. ards equation and finite element scheme to simulate this preferential flow in a soil profile with inclined layers, and (ii) to determine flow properties in a soil with funnel-type preferential paths. The model was first validated by testing against two-dimensional (2-D) laboratory results and then used to simulate water flow patterns in hypothetical 2D soil profiles made of medium sand with multiple randomly distribution inclined coarse layers. The following results were found from the numerical experiments: (i) funnel-type preferential flow paths could be deterministically simulated if soil layering structure, hydraulic conductivity of the overall profile, and threshold potential of the embedded coarse layers were known; (ii) distribution of the vertical component of flux was determined by the funneling effect along the upper coarse sand leases. The lenses located in deeper parts of the profile would only influence macrotortuosity of the preferential flow paths; (iii) funnel-type preferential flow paths were determined not only by soil structures and textures but also by water application rate; and (iv) although funnel-type preferential paths were very complex, the vertical component of flux could be very simply described by two stochastic parameters-the mean and standard deviation of a log-normal distribution after the. NAL Call No.: QH540.J6 ***************************************************************** 143. Simulating nutrient uptake by single or competing and contrasting root systems. Smethurst, P. J.; Comerford, N. B. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. Sept/Oct 1993. v. 57 (5) p. 1361-1367. Includes references. Descriptors: nutrient-uptake; root-systems; interspecific-competition; simulation-models; computer-techniques; mathematical-models; solutes-; transport-processes Abstract: Simulation of nutrient uptake by competing root systems is necessary to assist in the quantitativeunderstanding of these processes, to predict the consequences of competition for nutrients, and toprioritize future research on the mechanisms of nutrient competition. Our objective was to applypreviously published concepts to a computer model based on solute transport theory that would havethe ability to simulate nutrient uptake by root systems of one or two competing plant species. Analytical solutions were used for calculating the volume of soil allocated to each root systemand the concentrations of solute at the root surfaces. We included in the model (i) a depletion zone that increased with time until it reached the no-transfer boundary, (ii) an adjustment of theaverage concentration in the depletion zone to account for newly encountered solute as the zoneincreased in radius, (iii) a variable root-absorbing power (alpha), and (iv) a routine tocorrectly account for all soil in simulations with two contrasting root systems. Predicted uptakefor single-species scenarios in soils of contrasting nutrient supply characteristics was verifiedagainst that predicted by the commonly used Barber-Cushman model, NUTRIENT UPTAKE (maximumdiscrepancy was 23%), which utilizes a numerical solution. The ratio of uptakes predicted by both models was a function of c4 root radius, effective-diffusion coefficient, and buffer power in amore complex way than previously suggested in the literature. Sensitivity analysis indicated that. elliottii) relative to competing grass would be most sensitive to variations in root-length density of the grass, or insoil water content, if only soil parameters were examined. NAL Call No.: 56.9-So3 ***************************************************************** 144. Simulation by NCSWAP of seasonal nitrogen dynamics in corn. I. Soil nitrate. Lengnick, L. L.; Fox, R. H. Agron-j v.86, p.167-175. (1994). Includes references. Descriptors: zea-mays; computer-simulation; calibration-; simulation-models; nitrogen-cycle; cycling-; carbon-; soil-fertility; nitrates-; seasonal-variation; leaching-; soil-water-movement; soil-structure; soil-morphological-features; agricultural-soils; edaphic-factors; organic-fertilizers; pennsylvania-; inorganic-fertilizers Abstract: Computer simulation models of crop-soil systems offer the potential to increase understanding of soil N cycle processes, thereby improving management of N resources in agricultural systems. NCSWAP (Nitrogen, Carbon, Soil, Water, And Plant) is a comprehensive, deterministic computer model of the plant-soil system that simulates seasonal soil C and N cycles under the control of temperature, moisture, microbial activity, and crop growth. The objective of this study was to validate NCSWAP using data collected during a 3-yr N-rate study in central Pennsylvania that investigated seasonal N dynamics in corn (Zea mays L.) provided with N as liquid dairy manure or as NH4NO3. Seasonal soil NO3 concentration in the upper soil layer, seasonal aboveground N accumulation by corn, and water leached past 1.2 m during the second year of the study were used to calibrate input values controlling soil water flow and NO3 production from mineralization of soil organic N sources. The validation of NCSWAP identified several limitations in the water flow and C and N cycling submodels as well as in the potential of the model to simulate seasonal N dynamics in corn. Validation simulations were about as accurate as calibration simulations, reflecting the ability of the model to simulate C and N dynamics without recalibration from year to year. Much of the simulation error was related to an overestimation of NO3 leaching caused by the inability of the model's microporous flow submodel to simulate the macropore-influenced water flow in the well-structured soil used in the validation. NAL Call No.: 4-AM34P ***************************************************************** 145. Simulation models, GIS and nonpoint--source pollution: January 1991-December 1993. Makuch, J.; Emmert, B. Quick-bibliogr-ser. Beltsville, Md., National Agricultural Library. Feb 1994. (94-06) 78 p. Updates QB 92-69. Descriptors: simulation-models; agricultural-chemicals; water-quality; bibliographiesNAL Call No.: aZ5071.N3 ***************************************************************** 146. Simulation of bentazon leaching in sandy loam soil from Mellby (Sweden) with the PESTLA model. Boesten, J. J. T. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1231-1253. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: bentazone-; leaching-; sandy-loam-soils; soil-water; water-flow; drainage-water; evapotranspiration-; sorption-; pesticide-leaching-and-accumulation-model NAL Call No.: TD172.J6 ***************************************************************** 147. Simulation of dichlorprop and betazon leaching in soils of contrasting texture using the MACRO model. Jarvis, N. J.; Stahli, M.; Bergstrom, L.; Johnsson, H. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1255-1277. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: dichlorprop-; bentazone-; leaching-; transport-processes; soil-water; water-flow; solutes-; soil-texture; macropore-flow; soil-water-balance NAL Call No.: TD172.J6 ***************************************************************** 148. Simulation of dichlorprop leaching in three texturally distinct soils using the pesticide leaching model. Hall, D. G. M. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1211-1230. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: dichlorprop-; leaching-; simulation-models; macropores-; transport-processes; sandy-loam-soils; silty-soils; clay-soils; clay-loam-soils NAL Call No.: TD172.J6 ***************************************************************** 149. Simulation of simazine transport through soil columns using time-dependent sorption data measured under flow conditions. Kookana, R. S.; Schuller, R. D.; Aylmore, L. A. G. J-contam-hydrol v.14, p.93-115. (1993). Includes references. Descriptors: soil-pollution; simazine-; transport-processes; sandy-soils; flow-; sorption-; simulation-models NAL Call No.: TD426.J68 ***************************************************************** 150. Simulation of the movement of bentazon in soils using the CALF and PRZM models. Nicholls, P. H. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1157-1166. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: bentazone-; leaching-; simulation-models; pesticide-residues; flow-; leachates-; estimationNAL Call No.: TD172.J6 ***************************************************************** 151. Simulation of the water management system of a peach canning plant. Mate, J. I.; Singh, R. P. Comput-electron-agric v.9, p.301-317. (1993). Includes references. Descriptors: water-use-efficiency; recycling-; peaches-; canning-; water-management; simulation-models; water-systems; structural-design; water-flow; water-conservation; mathematical-models; computer-software; water-quality; water-reuse; extendtm-computer-software NAL Call No.: S494.5.D3C652 ***************************************************************** 152. Soil conservation in Cuba: a key to the new model for agriculture. Gersper, P. L.; Rodriguez Barbosa, C. S.; Orlando, L. F. Agric-human-values v.10, p.16-23. (1993). In the special issue: Low-input sustainable agriculture in Cuba / edited by J.A. Carney. Descriptors: low-input-agriculture; sustainability-; soil-conservation; soil-fertility; tillage-; fertilizers-; nitrogen-fixing-bacteria; green-manures; rotations-; intercropping-; vermicomposting-; agricultural-wastes; recycling-; animal-production; cubaNAL Call No.: HT401.A36 ***************************************************************** 153. Soil conservation planning at the watershed level using the Universal Soil Loss Equation with GIS and microcomputer technologies: a case study. Mellerowica, K. T.; Rees, H. W.; Chow, T. L.; Ghanem, I. J-soil-water-conserv v.49, p.194-200. (1994). Includes references. Descriptors: agricultural-land; watersheds-; water-erosion; risk-; universal-soil-loss-equation; geographical-information-systems; mapping-; computer-techniques; soil-conservation; erosion-control; regional-planning; land-resources; new-brunswick NAL Call No.: 56.8-J822 ***************************************************************** 154. Soil moisture and runoff simulations using four catchment rainfall-runoff models. Hughes, D. A. J-hydrol v.158, p.381-404. (1994). Includes references. Descriptors: soil-water; runoff-; rain-; soil-depth; watersheds-; grasslands-; catchment-hydrology; deterministic-models; variation-; accuracyAbstract: Four deterministic rainfall-runoff models are briefly described and applied to a small (0.18 km2) grassland catchment in the Eastern Cape Province of South Africa. The models vary in complexity, from a variable time step model with two soil layers and incorporating probability distribution principles for some of the parameters, through two daily time step models, to a relatively simple, but widely used, monthly time step model. The model parameters have largely been determined from measured physical characteristics (topography, soils, vegetation, etc.) of the catchment and not through calibration. As well as comparing the simulated runoff values, the model performances are compared using observed values of soil moisture measured over a period of some 29 months. Although the four models produce similar results, the variable time step model simulates the observed soil moisture variation most successfully and the monthly model least successfully. Most of the differenes in the simulation results can be explained by either the differences in complexity of the modelling approach or the resolution of the input data. NAL Call No.: 292.8-J82 ***************************************************************** 155. Soil nitrate leaching potential indices: using a simulation model as a screening system. Khakural, B. R.; Robert, P. C. J-environ-qual v.22, p.839-845. (1993). Includes references. Descriptors: nitrate-nitrogen; leaching-; losses-from-soil; simulation-models; groundwater-pollution; minnesotaAbstract: Simulation models LEACHM-N (Leaching Estimation and Chemistry Model) and NLEAP (Nitrate Leachingand Economic Analysis Package) were first tested using NO3 leaching data obtained from lysimeterand tile drainage studies conducted at three University of Minnesota experiment stations. Both simulation models did well in simulating total (seasonally accumulated) leaching loss of NO3-Nfrom the soil profile. LEACHM-N was selected as a screening took to develop soil NO3 leachingpotential (NLP) ratings using soil survey information and representative county weather stationdata. Simulated growing season total NO3-N leached from the soil profile (below 1.5 m) were usedas NLP index. Crop management practices and initial N were kept constant. Soil NO3 leachingpotential ratings for three Minnesota counties, Redwood, Stearns, and Sherburne were developed using this method. This soil NLP rating information was included in the Soil Survey InformationSystem (SSIS) to create leaching potential rating maps, which can be used to plan best Nmanagement schemes. NAL Call No.: QH540.J6 ***************************************************************** 156. A solute transport model for the acid leaching of copper in soil columns. Montero, J. P.; Munoz, J. F.; Abeliuk, R.; Vauclin, M. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. May/June 1994. v. 58 (3) p. 678-686. Includes references. Descriptors: solutes-; transport-processes; movement-in-soil; copper-; leaching-; acid-treatment; sulfuric-acid; convection-; dispersion-; mass-transfer; mathematical-models; mining-; technology-; solution-mining-technology Abstract: Modeling solution mining technique has recently received much attention in order to estimate metal recovery rates. We studied the acid leaching of Cu minerals found in mine tailings using a mathematical transport model and tab-scale experiments on both batches and saturated soil columns. The model is a one-dimensional macroscopic solute transport model that considers simultaneously (i) the convection, dispersion, and consumption of H2SO4, and (ii) the convection, dispersion, solubilization, and adsorption-desorption of Cu. Time-dependent batch experiments were carried out to understand the relationship between H2SO4 Consumption and Cu extraction in tailing Cu materials under stagnant conditions. Additionally, miscible-displacement experiments were conducted to obtain empirical data on Cu recovery in saturated soil columns that receive a constant pulse of H2SO4 and were designed to check the model's capability to simulate the transport phenomena. This was done by estimating the model parameters independently from the batch experiments. Since some findings from both experiments were consistent with each other, modeling assumptions, such as a second-order kinetic relationship for Cu dissolution (by H2SO4) and a first-order equilibrium isotherm for Cu, were appropriate in order to simulate the Cu recovery concentration at the outlet of each column. Finally, model equations were solved using finite differences and analytical solutions for Cu and H2SO4 transport equations, respectively, and model parameters were estimated using least squares techniques. NAL Call No.: 56.9-So3 ***************************************************************** 157. Spatial and qualitative reasoning for modeling physical processes. Vieu, L.; Martin Clouaire, R. AI-appl v.8, p.61-74. (1994). Includes references. Descriptors: erosion-; simulation-; models-; watersheds-; rain-; runoff-water NAL Call No.: QA76.76.E95A5 ***************************************************************** 158. Statistical water quality modelling for urban runoff control planning. Li, J. Y.; Adams, B. J. Water-sci-technol v.29, p.181-190. (1994). Selected Proceedings of the 6th International Conference on Urban Storm Drainage, September 12-17, 1993, Niagara Falls, Canada / edited by J.C. Marsalek and H.C. Torno. Descriptors: runoff-water; water-quality; urban-areas; probabilistic-models; simulation-models; urban-planning NAL Call No.: TD420.A1P7 ***************************************************************** 159. Streamlines for diffusive flow in vertical and surface tillage: a model study. Kirkham, M. B. Soil-Sci-Soc-Am-j. [Madison, Wis.] Soil Science Society of America. Jan/Feb 1994. v. 58 (1) p. 85-93. Includes references. Descriptors: soil-air; air-flow; flow-to-roots; oxygen-; diffusion-; transport-processes; horizontal-flow; mathematical-models; chiselling-; vertical-flow; vertically-tilled; hortizontally-tilled Abstract: Methods of tillage must permit adequate flow of O2 to plant roots. The objective of this work is to calculate streamlines of O2 flow from chisel holes oriented vertically and horizontally (surface tillage) in the soil to plant roots. Streamlines are perpendicular to equipotential lines. They also have the property that the difference in value between two streamlines gives the quantity of fluid (in this case, O2) flowing between them. Therefore, streamlines are often more important than equipotentials. Streamlines for flow of O2 from the chisel holes in the soil to plant roots were calculated by use of the relaxation method, in which both a coarse grid (2.54 cm on a side) and a fine grid (1.27 cm on a side) were used. Transit times were calculated from the flownet resulting from the streamlines and equipotential lines. Calculations with the coarse grid showed that, for the vertical chisel case, 75% of the flow goes out of the side of the chisel opening closest to the sheet of plant roots and 25% of the flow goes out of the side of the chisel opening farthest away from the sheet of plant roots; for the fine grid, the values are 63 and 37% for the two sides of the chisel hole, respectively. For both the vertically and horizontally tilled cases, stagnant areas were identified in the soil. Transit times were short for both tillage cases on the order of minutes), confirming the general assumption that diffusion is the major mechanism of gas transport in soil. NAL Call No.: 56.9-So3 ***************************************************************** 160. Sweet corn response to combined effects of saline water and nitrogen fertilization. Beltrao, J.; Asher, J. B.; Magnusson, D. Acta-hortic p.53-58. (1993). Paper presented at the International Symposium on Irrigation of Horticultural Crops, November 23-27, 1992, Almeria, Spain. Descriptors: zea-mays; sweetcorn-; irrigation-; saline-water; nitrogen-fertilizers; crop-yield; dynamic-models; simulation-models; salts-; leaching-; wilting-point; israelNAL Call No.: 80-Ac82 ***************************************************************** 161. Tennessee's NPS cost-share funds available for ag. Water-prot-conserv-manage v.6, p.2. (1993). Descriptors: water-quality; water-pollution; pollution-control; funds-; tennesseeNAL Call No.: TD424.35.T2W37 ***************************************************************** 162. Toxicity and estimated water quality criteria values in mallard ducklings exposed to pentachlorophenol. Nebeker, A. V.; Griffis, W. L.; Schuytema, G. S. Arch-environ-contam-toxicol. New York, Springer-Verlag. Jan 1994. v. 26 (1) p. 33-36. Includes references. Descriptors: pentachlorophenol-; feeding-; anas-platyrhynchos; toxicity-; tissues-; concentration-; water-pollution; threshold-models; bioaccumulationNAL Call No.: TD172.A7 ***************************************************************** 163. Translocation of alpha-sarcin across the lipid bilayer of asolectin vesicles. Onaderra, M.; Mancheno, J. M.; Gasset, M.; Lacadena, J.; Schiavo, G.; Martinez del Pozo, A.; Gavilanes, J. G. Biochem-j v.295, p.221-225. (1993). Includes references. Descriptors: aspergillus-; proteins-; mycotoxins-; liposomes-; membranes-; models-; transport-processes; glycine-max Abstract: alpha-Sarcin is a cytotoxic protein produced by the mould Aspergillus giganteus. Insertion of alpha-sarcin into asolectin membranes has been demonstrated by protein labelling with photoreactive phospholipids. alpha-Sarcin added externally to tRNA-containing asolectin liposomes degrades the entrapped tRNA. Trypsin-containing asolectin liposomes were also prepared. Encapsulated trypsin degrades alpha-sarcin, even in the presence of a large excess of external hen egg-white trypsin inhibitor to prevent any alpha-sarcin degradation outside the vesicles. These processes occur only with acidic phospholipids and were not observed when phosphatidylcholine vesicles were used. These results indicate that alpha-sarcin penetrates the lipid bilayer and becomes exposed to the lumen of negatively charged liposomes. NAL Call No.: QP501.B64 ***************************************************************** 164. Two-dimensional transport model for variably saturated porous media with major ion chemistry. Simunek, J.; Suarez, D. L. Water-resour-res v.30, p.1115-1133. (1994). Includes references. Descriptors: porous-media; transport-processes; models-; transient-flow; two-dimensional-flow; solutes-; ions-; soil-chemistry; subsurface-irrigation; surface-irrigation Abstract: We present the development and demonstrate the use of the two-dimensional finite element code UNSATCHEM-2D for modeling major ion equilibrium and kinetic nonequilibrium chemistry in variably saturated porous media. The model is intended for prediction of major ion chemistry and water and solute fluxes for soils under transient conditions. Since the solution chemistry in the unsaturated zone is significantly influenced by variations in water content, temperature, and CO2 concentrations in the soil gas, all these variables are also calculated by the model. The major variables of the chemical system are Ca, Mg, Na, K, SO4, Cl, NO3, alkalinity, and CO2. The model accounts for equilibrium chemical reactions between these components such as complexation, cation exchange, and precipitation-dissolution. For the precipitation-dissolution of calcite and dissolution of dolomite, either equilibrium or multicomponent kinetic expressions are used which include both forward and back reactions. Other dissolution-precipitation reactions considered include gypsum, hydromagnesite, and nesquehonite. Since the ionic strength of soil solutions can often reach high values, both modified Debye-Huckel and Pitzer expressions were incorporated into the model to calculate single ion activities. The need for an iterative coupling procedure between the solute transport and chemical modules is demonstrated with an example which considers root water uptake and irrigation using moderately saline water. The utility of the model is further illustrated with two-dimensional simulations with surface and subsurface irrigation from a line source. NAL Call No.: 292.8-W295 ***************************************************************** 165. Uncalibrated performance of the finite element storm hydrograph model. Hession, W. C.; Shanholtz, V. O.; Mostaghimi, S.; Dilaha, T. A. Trans-ASAE v.37, p.777-783. (1994). Includes references. Descriptors: erosion-; runoff-water; simulation-models; hydrological-data Abstract: The capability of the Finite Element Storm Hydrograph Model (FESHM) to simulate runoff events in an ungaged context was evaluated using data from an experimental watershed. The FESHM was used to simulate 30 runoff events over a 17-year period of record. The results from these simulations were evaluated using various statistical analyses. Regression methodology then was used to assess expected error and model bias. Runoff volumes were simulated more closely than peak flows. The model simulated runoff volume adequately for site-specific and screening analysis, but peak flow estimates were adequate only for screening purposes. The relationship of predicted to observed peak flows was found to be linear with low peaks being underpredicted and higher peak flows overpredicted. Although the runoff volume regression line was close to the desired equal value line, scatter or variance was great and no linear relationship was evident. Peak flow and volume simulation errors were related to rainfall intensity. These simulation biases are likely due to a combination of inadequate representation of the infiltration process by the model and inappropriate input parameters. A resolution of these biases and corrective action was beyond the scope of this study. However, a starting point is provided for future model investigations or modifications. Finally, it appears that some form of calibration is needed to use the FESHM with confidence. NAL Call No.: 290.9-Am32T ***************************************************************** 166. Urban storm drainage : selected proceedings of the 6th International Conference on Urban Storm Drainage, held in Niagara Falls, Canada, 12-17 September 1993. 1st ed. Marsalek, J. 1.; Torno, H. C.; International Conference on Urban Storm Drainage (6th : 1993 : Niagara Falls, C. Oxford ; New York : Pergamon Press, 1994. x, 465 p. : ill., maps. "Organized by International Association on Water Quality (IWAQ) [and] International Association on Hydraulics Research (IAHR)"--P. facing t.p. Descriptors: Urban-runoff-Mathematical-models-Congresses; Storm-sewers-Congresses; Drainage-Congresses; Water-quality-management-Congresses NAL Call No.: TD420.A1P7--v.29-no.1-2 ***************************************************************** 167. Use of a rainfall-runoff model for simulating effects of forest management on streamflow in the east fork Lobster Creek Basin, Oregon. Use of a rainfall runoff model for simulating effects of forest management on streamflow. Nakama, L. Y.; Risley, J. C.; Geological Survey (U.S.). Portland, Or. : U.S. Geological Survey ; Denver, CO : Earth Science Information Center, Open-File Reports Section [distributor], 1993. iv, 40 p. : ill., maps. Shipping list.: 93-653-P. Descriptors: Rain-and-rainfall-Oregon-Mathematical-models; Streamflow-Oregon-Mathematical-models NAL Call No.: GB701.W375--no.93-4040 ***************************************************************** 168. Use of GIS to rank counties for potential groundwater pollution. Smith, P. A.; Scott, H. D. Ark-farm-res v.42, p.4-5. (1993). Includes references. Descriptors: information-systems; groundwater-; groundwater-pollution; monitoring-; probabilistic-models; pesticides-; prediction-; arkansas-; geographic-information-systems NAL Call No.: 100-Ar42F ***************************************************************** 169. The use of pesticide leaching models in a regulatory setting: an industrial perspective. Russell, M. H.; Layton, R. J.; Tillotson, P. M. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1105-1116. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: pesticides-; leaching-; simulation-models; registration-; regulatory-issues NAL Call No.: TD172.J6 ***************************************************************** 170. Use of simulation models for registration purposes: evaluation of pesticide leaching to groundwater in the Netherlands. Brouwer, W. W. M. J-environ-sci-health,-Part-A,-Environ-sci-eng v.A29, p.1117-1132. (1994). Special Issue on the Evaluation and Comparison of Pesticide Leaching. Descriptors: pesticide-residues; leaching-; groundwater-pollution; netherlandsNAL Call No.: TD172.J6 ***************************************************************** 171. Use of the EPIC model to predict runoff transport of surface-appled inorganic fertilizer and poultry manure constituents. Edwards, D. R.; Benson, V. W.; Williams, J. R.; Daniel, T. C.; Lemunyon, J.; Gilbert, R. G. Trans-ASAE v.37, p.403-409. (1994). Includes references. Descriptors: pastures-; fertilizers-; poultry-manure; runoff-; simulation-models; water-quality; arkansas-; erosion-productivity-impact-calculator Abstract: The Erosion Productivity Impact Calculator (EPIC) model was applied to four fields established in "tall" fescue (Festuca arundinacea Schreb.) in northwestern Arkansas to predict runoff and transport of nitrogen, phosphorus, and sediment. Fertilizer form varied among the fields with two receiving inorganic fertilizer, one receiving poultry (Gallus domesticus) litter, and one receiving poultry manure. Soil and grazing parameters also differed among fields. Runoff and nutrient/sediment transport observed over 20 months were compared to EPIC predictions generated without calibration. Significant correlation between event predictions and observations were found in half the cases. There was significant correlation between observed and predicted calendar year total transport for all outputs except nitrate-nitrogen. The findings indicate that EPIC can accurately reflect runoff quality trends when executed without calibration for pasture fields in northwestern Arkansas. NAL Call No.: 290.9-Am32T ***************************************************************** 172. Use of the gleams model to estimate pesticide overland and subsurface transport in USDA Forest Service nursery applications. Craig, J. P.; Weiss, R. C. Water-sci-technol v.28, p.425-429. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: surface-water; water-systems; water-pollution; pesticides-; concentration-; usda-; forest-nurseries; drainage-water; models-; mississippi-; idaho-; michigan-; california-; groundwater-loading-effects-of-agricultural-management-systems NAL Call No.: TD420.A1P7 ***************************************************************** 173. Using GLEAMS to evaluate the agricultural waste application rule-based decision support (AWARDS) computer program. Ford, D. A.; Kruzic, A. P.; Doneker, R. L. Water-sci-technol v.28, p.625-634. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: agricultural-wastes; application-to-land; computer-software; pollutants-; loads-; water-pollution; simulation-models; groundwater-pollution; surface-water; groundwater-loading-effects-of-agricultural-management-systems; artificial-intelligence NAL Call No.: TD420.A1P7 ***************************************************************** 174. Using the CREAMS pesticides transfer sub-model at a rainfall simulation scale. Gouy, V.; Belamie, R. Water-sci-technol v.28, p.679-683. (1993). Paper presented at the IAWQ First International Conference on "Diffuse (Nonpoint) Pollution: Sources, Prevention, Impact, Abatement." September 19-24, 1993, Chicago, Illinois. Descriptors: runoff-water; water-pollution; pesticides-; rainfall-simulators; concentration-; prediction-; modelsNAL Call No.: TD420.A1P7 ***************************************************************** 175. Validation of AGNPS for small watersheds using an integrated AGNPS/GIS system. Mitchell, J. K.; Engel, B. A.; Srinivasan, R.; Wang, S. S. Y. Water-resour-bull v.29, p.833-842. (1993). Includes references. Descriptors: watersheds-; pollution-; runoff-; sediment-; erosion-; catchment-hydrology; simulation-models; geographical-information-systems; integrated-systems; topography-; illinois-; agricultural-nonpoint-source Abstract: The AGNPS (Agricultural NonPoint Source) model was evaluated for predicting runoff and sedimentdelivery from small watersheds of mild topography. Fifty sediment yield events were monitored fromtwo watersheds and five nested subwatersheds in East Central Illinois throughout the growing season of four years. Half of these events were used to calibrate parameters in the AGNPS model.Average calibrated parameters were used as input for the remaining events to obtain runoff and sediment yield data. These data were used to evaluate the suitability of the AGNPS model forpredicting runoff and sediment yield from small, mild-sloped watersheds. An integrated AGNPS/GIS necessary to thisstudy. This system is one where the AGNPS model was integrated with the GRASS (Geographic Resources Analysis Support System) GIS (Geographical Information System) to develop a decisionsupport tool to assist with management of runoff and erosion from agricultural watersheds. The running the model,and interpretation of the results. NAL Call No.: 292.9-Am34 ***************************************************************** 176. Water pollution II : modelling, measuring, and prediction. Brebbia, C. A.; Wrobel, L. C. L. C. 1.; International Conference on Water Pollution: Modelling, M. a. P. 2. 1. M. I. Southampton ; Boston : Computational Mechanics Publications, c1993. 739 p. : ill.. "Contains the proceedings of the Second International Conference on Water Pollution held in June 1993, Milan, Italy"--P. [4] of cover. Descriptors: Water-Pollution-Congresses; Water-Pollution-Mathematical-models-Congresses; Water-Pollution-Measurement-Congresses; Water-quality-Congresses; Sewage-Purification-Congresses NAL Call No.: TD419.5.W365--1993 Return to Bibliographies Return to the Water Quality Information Center at the National Agricultural Library. Last update: April 27, 1998 The URL of this page is http://www.nal.usda.gov/wqic/Bibliographies/eb9609.html J. R. Makuch /USDA-ARS-NAL-WQIC/ [email protected]