Location: Coastal Plain Soil, Water and Plant Conservation ResearchTitle: Application of APEX Model in evaluating streamflow and sediment yield in Stung Chinit Catchment
|NUT, NARETH - Royal University Of Agriculture|
|REYES, MANUEL - Kansas State University|
|MIHARA, MACHITO - Tokyo University Of Agriculture & Technology|
|CHAN, SAKDANUPHOL - Royal University Of Agriculture|
|SOURN, TAINGAUN - Ministry Of Planning-Cambodia|
Submitted to: International Journal of Environmental and Rural Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2021
Publication Date: 1/25/2022
Citation: Nut, N., Reyes, M., Sigua, G.C., Mihara, M., Chan, S., Sourn, T. 2022. Application of APEX Model in evaluating streamflow and sediment yield in Stung Chinit Catchment. International Journal of Environmental and Rural Development. 12(2):161-170.
Interpretive Summary: The Stung Chinit catchment is one of the major tributaries of Tonle Sap Lake in Cambodia. There is an intensified economic activity in the catchment, including significant land concessions, infrastructure developments, and demographic pressures. As a result, soil erosion occurred from the upstream to the downstream of the catchment due to agricultural land expansion by encroaching on the forest land. Our research aimed to evaluate the APEX model's performance and applicability in estimating streamflow and sediment yield as well as identifying the extent of soil erosion in Stung Chinit Catchment, Cambodia. Results showed that the Stung Chinit catchment experienced soil loss during 2011 and 2013 due to the catchment area's significant flooding occurrence. A calibrated and validated APEX model was able to estimate streamflow and sediment yield. The model also provided an excellent qualitative description of land uses and geographic indicators effects on streamflow and sediment estimation. The mean annual surface runoff was 212.03 millimeters (mm) varied from 72.56 mm to 435.59 mm. In contrast, the sediment yield ranged from 16.0 tons/hectare (ha)/year in the lowlands of the Stung Chinit catchment main river channel to 68.2 tons/ha/year in the highlands annual sediment yield of 29.2 tons/ha/year. Most of the sediment yield came from the eastern part and near the Stung Chinit catchment outlet. Land use management in lowlands could be improved while practicing soil erosion control methods in the highlands and minimizing tillage practices in areas with slopes greater than 25 percent (%) to prevent soil losses. Due to data limitations, we did not compare the impact of land-use change on streamflow and sediment load in this watershed. However, we demonstrated the importance of determining how streamflow and sediment load drivers will change in response to land-use change and climate change in the watershed. Nevertheless, this search should develop a reliable streamflow model capable of illustrating and defining the critical source areas and conditions of sediment yield in the watershed.
Technical 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 (Nash–Sutcliffe Efficiency, NSE; regression coefficient, R²; and percent bias, PBIAS) of streamflow calibration (1997-2015) were 0.62, 0.60, and 2.25%, 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 16.0 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. Our model simulation and validation has developed a reliable streamflow model, which is capable of defining the critical source areas and conditions of sediment yield in the watershed.