Evaluation of Meteorological Drought Effects in the Reduction of Ground Watertable (Case study: Tabriz Plain)

Tabriz plain has located in east of Urmia lack. In certent decades alternate and continued droughts have occured in the region and Tabriz plain. Contemporary ground watertable has decreased greatly. Therefore it seems there is a significant interaction between meteorological drought and fall of ground watertable. The goal of this study is to do research on drought, to find precipitation trend, analyze groundwater hydrograph and the evaluation of meteorological to drought effects in the reduction of ground watertable using SPI index and bivariate regression in Tabriz plain. For this purpose, we used meteorological data (monthly precipitation) of Tabriz plain station for the time period 1351-1383 for determination of drought periods. Monthly data of watertable from observation and piedzometry wells for the 1370-1383 were used for the representation of ground watertable variation, by the use of Arc/GIS, Arc/View, Excel and Surfer. The results show that in recent decades precipitation trend has been negetive. Also ground watertable has decreased and the watertable has fallen around 3.94 m in time period of 1370-1383. Groundwater drought relative to meteorological drought occurs two months later in Tabriz plain.