Estimating Hydrological and Hydrogeological Parameters of Watershed Using SWAT Model (Case study: Balukhlu-chay Basin)

The aim of this study was estimation of some hydrological and hydrogeological parameters for Balukhlu-chay basin, Ardabil province, using SWAT model. Required data for this study including soil properties, soil, land use and topography maps, daily rainfall, temperature, air humidity and surface water discharge were collected from Natural Resources Office and Regional Water Company of Ardabil province. Curve number, coefficient of evaporation from soil surface, soil water availability, precipitation, snowmelt temperature, and delay time for aquifer recharge were identified as the most important and sensitive parameters. The hydroclimatologic data of the years 2000 to 2004 were used in calibration stage and the data of the years 2005 to 2007 were used in validation stage of the model evaluation. The R2, RMSE and RE indices were used to evaluate the goodness of simulation. Hydrological and geohydrological parameters including curve number, delay time for aquifer recharge and saturated hydraulic conductivity were estimated. The values ​​of these parameters, respectively 70 to 80, 30 days, and 12 to 24 mm per hour were estimated for Balukhlu-chay basin. During calibration process, the values of 0.81, 0.98 and 0.07 were obtained for R2, RMSE and RE, respectively. Similarly, these values were calculated as 0.63, 0.89 and 0.08 for R2, RMSE and RE, respectively, during the validation. The results showed that river flow was well simulated by the SWAT model, compared with the measured data. The amount of error in the validation stage showed that hydrological and hydrogeological parameters were estimated with good accuracy.