[AHW20-P05] Estimating water budget in forested watershed flowing to Ariake-sea using SWAT model
Keywords:Ariake-sea, water budget, SWAT, forested watershed
We chose Kikuchi-river as the model watershed, which locates in the middle of Kyusyu island and has the third largest area (996 km2) among the rivers flowing to Ariake-sea. This watershed is mainly covered by forest (about 70%). We collected land use data, soil data, climate data and 30m mesh digital elevation model (DEM) data of this watershed in order to establish the model, and observed data of daily stream flow from 2008 to 2015 to calibrate and evaluate the model performance. Parameters relating to water budget were modified according to the result of calibration.
The model performance was evaluated by 3 indices such as Nash-Sutcliffe index. The difference of estimated water budget between land-use indicated the function of forested area as decreasing surface flow and increasing groundwater recharge. In conclusion, modelling the water budget using SWAT model has potential to understand water system and the contribution of forested area to Ariake-sea environment.