the effect of 1991-2001 droughts on ground water in neishabour plain

abstract this research investigates the effect of drought on ground water table of neishabour plain. the precipitation data of nishabour synoptic station during 1990-2001, the bar climatology station during 1964-2001 and the data of hydrometric stations of kherv and bar in 1996-2001 have been used as the base of analysis. the method of herbest et all has been used to analyze the drought. using the effective precipitation and effective flow, the date of start and end of drought for the study region has been specified and then the time and intensity of drought have been calculated. the analysis shows that the main reason for the fall of the underground waters table level is the irregular use for agricultural consumptions. the climatic drought has had a direct effect on running water and it has also had direct effect on underground water of the region with a time lag. it was appeared that alluvial fan areas of neishabour plain have a less decrease compared with the central and southern areas in spite of much consumption of water by deep wells. key words: climatic drought; effective precipitation; depletion of water table; hydrograph; ground water