Quantitative Effects of Rainfall Variations on Groundwater Resources in Different Time Scales: A Case Study of Gowhar-Kuh Plain, Sistan and Baluchestan, Iran

The evaluation of climatic impacts on groundwater level in dry and wet periods is very important for the optimum management of water resources and prevention of crisis caused by droughts. In this study, the relationship between rainfall variations and groundwater level oscillations in Gowhar- Kuh plain has been investigated. The standardized precipitation index (SPI) has been used to quantify the precipitation variations, while the standardized water table index (SWTI) has been developed to assess groundwater level fluctuations. The correlation and time delay between SPI and quantitative parameters of groundwater status (water table elevation and SWTI) has been calculated using modified cross correlation function (MCCF). This method allowed the calculation of cross correlation between unequal length time series. The results are indicative of a high correlation coefficient (0.9) on long time scales with a time delay of about 7 to 8 years.