Evaluation of Different Runoff Curve Number (CN) Approaches on Water Regulation Services Assessment in Intermittent Micro Catchment Dominated by Oil Palm Plantation

Surface runoff is a primary driving factor for water regulation services on oil palm plantations as it determines the hydrological components and other biogeochemical process. Therefore, understanding their interaction contribution within watershed system important to support decision-making system. Here, we applied Soil Water Assessment Tools (SWAT) model simulate an intermittent micro-catchment dominated by plantation in Harapan Landscapes, Batanghari Regency, Jambi Province. In this study, used two different curve number (CN) approaches SWAT model, namely soil moisture (CN-SM) plant evaporation (CN-ET), evaluate applicability uncertainty assessing services. was automatically calibrated validated against daily observed streamflow data. The results showed that performed well indicated hydrograph visual interpretation statistical indicators. performance good calibration validation both with high R2 Nash-Sutcliffe Efficiency (NSE). Also, acceptable P-factor >70% R-factor <1. Differences CN-SM CN-ET's conceptual structure have caused variations parameters' best-fit value sensitivity simulations, which implicated components' output However, CN-ET approach less responsive area's biophysical conditions generation than one. This generated low storage overestimated actual evapotranspiration. modeling exercise selection of CN considering characteristics calculating simulating balance component such watershed. accuracy simulation will significantly influence management recommendations improve regulation's sustainability.