Evaluating the Impact of Watershed Management Practices on Water Balance Components and Sediment in Verdij–Varish Catchment

Watershed management practices and the strategies towards its development are among the important articles in water and environment sections in governmental higher documents. One of the important aspects of watershed’s development is the Integrated Water Rsources Management. The focus of this research is on comprehensive assessment of the effects of these practices on a catchment's water balance. To this end, the SWAT model was used as a comprehensive simulation tool. Verdij - Varish Basin was selected as a case study since it has served as a pilot area for the implementation of various watershed management practices (biological, biomechanical and mechanical) in recent years The SWAT model has been calibrated and validated for the period of 2017 to 2018. The values of R2 and Nash Sutcliffe (NS) coefficient were respectively equal to 0.85 and 0.7 for the calibration period and 0.89 and 0.63 for the calibration period. The watershed management practices were simulated by the SWAT model and their effects on water balance components and sediment were evaluated. As compared to the original state, seeding has increased soil moisture in the unsaturated area by about 60% and transplant has reduced runoff by 36%. Using multi-criteria decision making method, a type of biological practice (seeding) was determined to be the best management practice for increasing soil moisture and reducing outflow in Vardij Varish catchment.