Hydrological Drought Analysis of Groundwater in Mehran Plain Using GRI Index

Groundwater drought occurs when the groundwater of an area is affected by prolonged drought. In this type of drought, first the feeding, then the water level and finally the discharge of groundwater systems due to drought are reduced. Therefore, in order to know the drought status of groundwater in Mehran plain in Ilam province, GRI index was used. For this purpose, statistics of 23 years from 1996 to 1397, 19 hydrometric stations were selected after verifying and reconstructing the data. After entering the primary raw data in the step-by-step calculation file of the GRI index, calculate the mean, LN, U factor, Shape parameter and Scale parameter, logarithm in base e and possible GAMMA distribution for the input data and calculate the value of H (x) And its separation in the range between 0.5-0 and 1.5-1 and the calculation of the parameter t and Z and at the end of extracting the final results of the calculation of the GRI index by combining the calculations in the two final tables. The results show that the drought in Mehran plain from 1375 to 1388 is close to normal, but with a sharp fluctuation and from 1388 to 1397 has suffered mild drought.