Groundwater Vulnerability Assessment by the use of Drastic-Nw Modified model (Case study: Kuchesfehan-Astane plain).

Water shortage is one of the society''s problems regarding to population increase and industries development nowadays. In addition to quantity، water quality is of special importance. The quality of groundwater and prevent further contamination، especially in areas where have highly vulnerable aquifers is particularly important. Most of the canals in the Kuchesfehan-Astane plain are no lining and this factor leads to more water waste. High water leakage has the main role of underground water pollution in this region because ground water level is high and the salient farming is the water farming in this region. This article attempts to determine the rate of water leakage from traditional irrigation canals by the Seep w software and regarding this the network parameter was made and added to drastic parameters as the 8th parameter. A new plan was drawn that presented better results regarding to the standard drastic plan. It is realized that the vulnerability rate of NW drastic plan is about 7. 9 percent but in the standard drastic plan is about 1. 67 percent by the comparison of standard drastic plan and NW drastic plan. Correlation coefficient was used for the appropriateness assessment and comparison of two plans (between vulnerability and nitrate density factors) and it was about 40 percent for the standard drastic and 60 percent for the NW drastic that shows the high accuracy of NW drastic plan.