Forecasting of Groundwater Table and Water Budget under DifferentDrought Scenarios using MODFLOW Model(Case Study: Garbaygan Plain, Fars Province, Iran)

The frequency and severity of hydrological droughts are often defined on a watershed or river basin scale. Althoughall droughts originate with a deficiency of precipitation, hydrological droughts are usually out of phase with or lagthe occurrence of meteorological and agricultural droughts. It takes longer for precipitation deficiencies to show upin components of the hydrological system such as soil moisture, streamflow, and groundwater. In fact, the presentresearch has focused on forecasting the effects of drought on water budget and groundwater table using MODFLOWmathematical model in Garbaygan plain, located in the southeastern of Iran. In this study four scenarios includingwet year, normal, moderate and severe drought have been considered. It means in which the rate of precipitation bysolving of SPI index under four mentioned scenarios has been predicted. Then using an agreement with relationshipbetween precipitation and recharge (natural and artificial) in transient calibration, the best estimators have been fittedfor forecasting of recharge. The results showed that firstly, the hydrograph of aquifer was changing as the waterbudget was positive until 1996, while in 1993, the storage of aquifer increased more than 6 Mm3 but from 1997 it hasdecreased and in 2006 the maximum of aquifers’ shortage about -2/27 Mm3 observe. In addition, the forecasting ofwater budget illustrates that under different precipitation conditions (from wet year to severe drought) it will benegative as it varies from -1/7 to -2/27 respectively. Moreover, groundwater level will fluctuate in differentconditions and it will decline more in the locations with high densities of farming wells

کلیدواژه ها:

Groundwater drought. MODFLOW. Water budget ، Garbaygan plain