Application of the Hydrological Model SWAT in the Zayandeh Rud Catchment

Abstract

Soil and Water Assessment Tool (SWAT) was used in combination with SUFI2 program to calibrate and validate a hydrologic model of Zayandeh Rud watershed at the sub-basin level with uncertainty analysis to explicitly quantify hydrological components of water resources on a monthly time step. The specific goal was to simulate natural historical and future streamflow data to be used in MIKEBASIN (MB) water allocation model for water resource management of the watershed. A first run of the SWAT model, prior to calibration, revealed that many stations are highly influenced by water diversion channels, reservoirs and dams, springs, extraction wells, and inter-basin water transfers. After identifying and properly accounting for natural and anthropogenic changes, we calibrated the model using discharge data of 17 hydrometric stations with a regional parameterization approach. Overall, the basin wide bR2 was improved from the average of 0.27 to about 0.44 in upstream region, while it improved from 0.39 to about 0.46 in downstream catchment. The calibration performance in downstream stations was highly depended on the quality and quantity of water use and water diversion data, while it was influenced by the climate data in upland areas. To meet the ultimate goal of the project, the calibrated and validated SWAT model was finally used to generate daily naturalized stream flow data to feed the MIKE BASIN model for the management and allocation purposes.