conjunctive use of ground and surface water can increase reliability of the water supply by providing independent sources. in this study, corrected utility-efficient pro-gramming that allows for more than one seasonal irrigation depth for each crop was used to determine the amount of utility maximizing investment in the well capacity for conjunctive use. results showed that optimum investment a...

Over three million hectares of salt-affected soils characterized with high salinity and sodicity caused serious land degradation in Songnen Plain, northeast China. Soil salinity–sodicity heterogeneous distribution under microtopography is usually influenced by several environmental factors. The side direction movement of soil water driven by water from depression is the key factor that aggravat...

there are 3700 wells in tehran city, of which 850 are deep wells. to determine tehran ground water quality, as a pretest we selected 102 wells by simple random sampling; water analyses were made according to the latest edition (1985) of the standard methods. comparisons of the obtained results with who standards show that only 0.98% of the samples go beyond the maximum desirable concentration o...

Profiles of ground water pesticide concentrations beneath the Nebraska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides and their transformation products were detected in 7848 ground water samples from the unconfined water table aquifer. Triazine an...

for better understanding of tehran ground water, samples were taken randomly from 340 out of 655 deep & semi deep wells in 1993, which dug by tehran water supply and sewage engineering company. 260 water specimens were examined chemically and physically and compared with the 1993 world health organization (who) and food and agriculture organization (fao) criteria and analyzed statistically. log...

Scour is a phenomenon that occurs as a result of natural erosion by ground water flow and transport of seabed material. In this research, scour around the legs of marine structures is simulated using the FLOW3D.V.9.3™ commercial software. The general scour model consists of two components, namely, the lift and thrust forces. The drag force, that is inserted to the structure, is a combination of...

Ground water samples (37 to 186 m depth) from Baldwin County, Alabama, are used to define the hydrogeology of Gulf coastal aquifers and calculate the subsurface discharge of nutrients to the Gulf of Mexico. The ground water flow and nitrate flux have been determined by linking ground water concentrations to 3H/3He and 4He age dates. The middle aquifer (A2) is an active flow system characterized...

background: nitrate and nitrite compounds are considered as groundwater’s contamination factors, which in recent years, their densities have been growing in these resources. this study was conducted aiming to measure nitrate and nitrite density in drinking water wells in villages around the industrial estate, city of orumieh, and to compare them to the approved standards. methods: this was a de...

Main perennial rivers of Gujarat, Tapi, Narmada, Mahi and Sabarmatiare meeting Arabian Sea in Gulf of Khambhat. The out flow of Mahi River intothe sea is decreased due to construction of dams like Bajaj Sagar, Kadana, Panamand Wanakbori weir. So, Tidal effect of sea and sea water intrusion is beingincreased on landward side. Moreover, due to erratic nature of rainfall andimproper management of ...