in dry parts of asia and africa where the rain was sparse and the surface water inadequate, man has had to search for-other sources of water namely ground water. through this need he learned to tap ground water and extract it to the surface. thus qanats were developed in persia.techniques of qanat construction were later introduced by persians to parts of asia and dry lands of africa.constructi...

Concern about NO− 3 leaching and groundwater pollution from corn monoculture has prompted an investigation of alternative production systems that reduce leaching. It is hypothesized that both intercropping and water-table control could increase N uptake and reduce the quantity of N that might be lost due to leaching. This study compared corn (Zea mays L.) with annual Italian rye-grass (Lolium m...

Introduction: A major objective of the Mars Scout mission, Phoenix, is to characterize the present state of water in the martian environment, at a location where water may play a significant role in the present and past habitability of Mars [1]. Given the generally dry and cold climate of Mars today, any substantial amount of water is expected to occur in the form of ground ice within the regol...

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...

varying degrees of water solubility. Some additives (e.g., methyl tertiary-butyl ether and alcohols) are highly soluble. Other components (e.g., benzene, toluene, ethylbenzene, and xylenes) are slightly soluble. Many components (e.g., ndodecane and n-heptane) have relatively low water solubility under ideal conditions. Physical and chemical properties which affect transport and fate of selected...

varying degrees of water solubility. Some additives (e.g., methyl tertiary-butyl ether and alcohols) are highly soluble. Other components (e.g., benzene, toluene, ethylbenzene, and xylenes) are slightly soluble. Many components (e.g., ndodecane and n-heptane) have relatively low water solubility under ideal conditions. Physical and chemical properties which affect transport and fate of selected...