Investigation on human activities effects on water resources trend of Urmia Plain

Considering the importance of Lake Urmia, the purpose of this research is to survive the human activates on the trend of surface water and groundwater changes in the Urmia plain. For this purpose, the changes in input and output discharge, aquifer drainage and land use changes in the Urmia Plain were studied on the basis of nine hydrometric stations data (during 1973-1903) and information of 74 piezometers and using satellite images. The test used for trend analysis was Mann-Kendall nonparametric test with considering the effect of autocorrelation. According to the results, the trend of input discharge from the Nazlou-Chay, Rouzh-Chay and Barandoz-Chay sub-basins to the Urmia Plain was decreasing and the negative trend of outlet discharge related to the Rouzh-Chay, Shahr-Chay and Barandoz-Chay sub-basins was significant at 95% confidence level. Comparison of the results the difference between discharge average during after and before 1995 (the year which in it the lake begins to dry) showed that at all stations except Ghassemlou, there is a significant difference between average discharge during these two periods. The value of the statistic (Z = -2.18) indicates a significant decreasing trend at 95% confidence level for the drainage volume of the aquifer reservoir. The results of this study showed that discharge to Lake Urmia in all seasons had a decreasing trend during the studied period and serious actions should be done to manage water resources in the region.