Investigation the Changes of Water Resources Deficit Signatures in Lake Urmia Basin

Monitoring long-term changes in water resources in each basin acts as a monitoring system. Investigating changes in water resources, how they are altered and their percentage in each basin will greatly contribute to the water resources management. In this study, after introducing water deficit signatures, we investigate the changes in these signatures using modified Mann-Kendall test with eliminate the effects of internal autocorrelation. In this study, the values of precipitation, discharge and groundwater levels deficiency were measured during 10, 30 and 60 days durations in 12 sub basins in Lake Urmia Basin. Rain gauge and hydrometric stations were used for precipitation and discharge values and the entropy theory was used to select the piezometer stations. The results of changes in deficiency signatures values showed that the overall changes are incremental, which in some cases is significant and in some cases not significant. In general, the results indicated that, on average, the rainfall deficit, discharge deficit and groundwater level deficit signatures increased by 52, 35, and 23 percent, respectively, over the long-term average. These changes for Lake Urmia Basin indicate an increase in meteorological, hydrological and groundwater droughts.