CONTINUOUS HYDROLOGIC MODELING OF ZARD RIVER BASIN IN IRAN USING SOIL MOISTURE ACCOUNTING

The main purpose of this study is to calibrate a continuous hydrological modeling based on Soil Moisture Accounting (SMA) method for Zard River basin in Iran. To perform the HEC-HMS modelin the present study, spatial data such as soil map, digital elevation model, land use, and land cover map were used to define catchment boundary and other physiological characteristics of basin. The model was calibrated for periods of 1975-1978 and validated for the periods of 2003-2005. Four statistical indicators are used to evaluate model in both calibration and validation periods. The indicators include: coefficient of determination for monthly volumes (R2), Percentage Error for monthly Volumes (PEV),Root Mean Square Error of daily peak flows (RMSE), and Mean Absolute Error of daily peak flows (MAE). The value of this indicators incalibrated period are =0.92, Log=0.93PEV= 1%, RMSE=8.5(m3/s)and MAE=3.2(m3/s)And for validating period are =0.87, Log=0.8,PEV= -0.5%, RMSE=183(m3/s)and MAE=6.2(m3/s)Also Sensitivity analaysis showed that soil storage is the most sensitive parameter for the calibration period and GW2 percolation is the least sensitive parameterThe results show that SMA method in HECHMS conceptual model perform well enough and can be used for continuous longterm rainfall-runoff modeling in Zard River basin