Evaluating the Effects of Watershed Subdivision on Hydrological Simulation by Swat Model in an Arctic Watershed

Abstract

Abstract The hydrological model SWAT is a state-of-the-art tool for environmental and water resources management. Like other semi-distributed models, the whole river basin in the SWAT model is delineated into smaller sub-basins prior to conducting the simulation. Watershed delineation is an importance step since it could potentially influence the modelling results. The present study aimed to conducte an investigation of the effects of watershed delineation schemes on hydrological simulation in an Arctic watershed Målselv, north of Norway. Four delineation schemes were set up with different threshold drainage area (TDA) from fine to coarse including 100 ha, 2,000 ha, 5,000 ha and 10,000 ha. The model was run on monthly time step from 1979-2012. The results showed higher variation of average annual precipitation and runoff especially in the upstream sections of the watershed by the fine TDA schemes compared to the coarse ones. The average monthly precipitation and runoff slightly increased from the finest TDA scheme to the coarsest scheme. All TDA schemes reproduced the observed tendency of the average monthly and annual streamflow although the peak flow was over and under estimated at different hydro-gauging stations. The higher value of estimated streamflow was found at the coarsest scheme.