Quantitative simulation of surface and groundwater resources in Behshahr - Bandar-e-Gaz Plain Using SWAT model

Optimal management of water resources in a plain with land uses requires proper prediction of water resources response using efficient models. In this research, Soil and Water Assessment Tools (SWAT) model was used to simulate surface and groundwater resources in Behshahr - Bandar-e-Gaz Plain. After analysis the sensitivity, calibration and validation of the model was performed based on river flow data of 2007- 2013 and 2014- 2017, respectively. Groundwater table simulation was done by simulating the recharge rate per hydrological response unit (HRU). The results of sensitivity analysis showed that the parameters GW_REVAP, GW_DELAY, SHALLST, DEEPST, RCHRG_ DP, ALPHA_BF, SOL_AWC, CN, HRU_SLP, ESCO, USLE_P, OV_N, FILTERW and EPCO were the most sensitive parameters. In order to evaluate of the model, the performance criteria of Nash- Sutcliffe (NS) and Correlation coefficient (R2) were used. In the calibration stage, these coefficients ranged from 0.56 to 0.93 and 0.74 to 1.00, respectively, and in the validation process were in the range of 0.56 to 0.84 and 0.66 to 0.92, respectively, indicating the acceptable accuracy of the model in river flow simulation. Comparing the observed and simulated water table depths, NS (0.81) and R2 (0.91) coefficients indicated the capability of the model to simulate groundwater level. According to the results of the water balance analysis, the most of the total water input to the plain, it’s 60% was used for evapotranspiration and it’s small parts as 18% and 22% allocetaed to surface runoff and infiltration, respectively.