drain envelopes play significant roles in the performance of drainage systems due to theirreduction in letting sediments into the drainpipes and also because of an increase in thehydraulic conductivity of soil around the drainpipes. throughout the present research, theeffect of a one 1000 hour flow on dual envelopes consisting of geotextile as a means ofimproving the hydraulic gradient and rice...

Risk assessment of central water supply systems a case study. This paper presents methods for identification and risk assessment of central water supply systems, exemplified by a case study of the central water supply system in Luna locality, Cluj county during 2009-2010. System assessment was performed by means of previous data on water quality monitoring and water samples analysis for the par...

Vertical migrations of living organisms and settling of particle-attached organisms lead to uneven distributions of biota at different depths in the water column. In ballast tanks, heterogeneity could lead to different population estimates depending on the portion of the discharge sampled. For example, concentrations of organisms exceeding a discharge standard may not be detected if sampling oc...

The hierarchy of models applicable to transient free surface problems of ground water ̄ow to drains is discussed. The model choice is related to drain type and dewatering stage. Flow pattern is illustrated to vary with decrease of the water table. Simulation of drains and corresponding boundary conditions are discussed. # 2000 Elsevier Science B.V. All rights reserved.

Recent developments in urban drainage modelling allow for a more realistic coupling of the two-dimensional (2D) surface and one-dimensional (1D) sub-surface drainage domain exchanging water through storm drain inlets instead of a sub-catchment approach based on manholes. Experience has shown, however, that comprehensive records of storm drain inlet locations are often missing or incomplete, pre...

In recent years, the poultry industry has seen a steady growth in Iowa. With the increase in the broiler and egg industry, the public is concerned about the potential threat to environmental quality (surface and subsurface water and air quality) from increased volumes of poultry manure. Although the effect of poultry manure on crop production has been studied, its effects on water quality, unde...

Tailwater recovery systems (TWR) provide an excellent testbed for examining nutrient loading from agriculture non-point sources, such as pre-harvest rice (Oryza sativa L.) field drains, on receiving waters. In this study, the focus was to use continuous sampling of nitrate-nitrogen (NO3−-N) concentration, paired with discrete grab samples of water which were analyzed for total nitrogen and inor...

Excessive use of animal manure on agricultural lands can impact the quality of surface and groundwater resources. A three–year study (1998–2000) was conducted on nine 0.4–ha plots and on six 2.1–m 2 lysimeters to investigate the effect of two nitrogen (N) application rates from laying hen manure and one N application rate from urea ammonium nitrate (UAN) fertilizer on surface and groundwater qu...