Impact assessment of climate change on groundwater table using of balance conceptual model (Case study: Birjand Plain)

Water resource management in arid and regions has high importance. Since in these regions most of demands are programmed based on groundwater so inform of quantity and quality situation of groundwater is very necessary. General Circulation Models (GCMs) outputs are useful instrument for forecast of variations of hydrological parameters. In this study to assessment of global warming impacts variations of rainfall patterns which has been influenced by climate change effects were first evaluated by using of best GCMs outputs and in continue balance conceptual model was examined to analysis of quantity situation of Birjand Aquifer. Calibration and validation of balance conceptual model was performed by using of Multi-objective Particle Swarm Optimization and observation water table (from 1390 to 1393). Fitness functions in this optimization were RMSE and R2. Results of optimization showed that ranges of fitness function in calibration period reached from 0.96 to 0.2 and from 0.77 to 0.97 for RMSE and R2 respectively. Also value of these indices reached 0.84 and 0.91 for RMSE and R2 respectively in validation period. In after step estimation of aquifer water table performed by input of rainfall predicted into balance conceptual model. Relying of conceptual simulations it is expected that cumulative head loss and groundwater table will reach to 7 and 1315.9 m in end of future period respectively.