Application of APEX Model in Evaluating Streamflow and Sediment Yield in Stung Chinit Catchment

Abstract

Streamflow and sediment yield are important indicators to understand the alterations in hydrological processes as well as the supply and transformation of nutrients and biological productivity in the ecosystem. The main objective of this study was to evaluate the performance and applicability of the APEX model in estimating streamflow, sediment yield, and quantifying the soil erosion in Stung Chinit Catchment. The result indicates that the APEX model performed well in accurately simulating the monthly streamflow and annual sediment yield in the watershed. The overall statistical indicators (NSE, R², and PBIAS) of streamflow calibration (1997-2015) were 0.60, 0.62, and 2.50%, respectively. The validation statistical indicators (NSE, R², and PBIAS) for streamflow were 0.71, 0.80, and 28.22%, respectively. The mean annual surface runoff was 212.03 mm; varied from 72.56 mm to 435.59 mm. The average annual sediment yield varied from 10.21 tons/ha/year in the lowlands of the Stung Chinit catchment main river channel to 68.2 tons/ha/year in the highlands, with an annual average of 29.2 tons/ha/year. Most of the sediment yield came from the eastern part and near the outlet of the Stung Chinit catchment.