Modeling Future Scenarios for Moiben River Flow Using SWAT and CA-Markov: Implications for Sustainable Watershed Management

Abstract

This study utilized an integrated Cellular Automata–Markov (CA–Markov) and Soil and Water Assessment Tool (SWAT) modeling approach to forecast the hydrological response of the Moiben River watershed to future land use and climate scenarios for the year 2055, recognizing the river's critical role in regional water supply. The CA–Markov model, informed by historical LULC trends between 2005 and 2021, projected a Business-as-Usual (BAU) scenario characterized by dominant agricultural expansion (covering over 71% of the area) at the expense of crucial Natural Forest and Grassland covers. Subsequently, the SWAT model, calibrated and validated for the watershed and forced by the Representative Concentration Pathway (RCP 6.0) climate scenario, simulated the corresponding changes in river flow. The simulation results revealed a statistically significant destabilization of the river’s flow regime (p<0.001) compared to the 2021 baseline, confirming a critical loss of the watershed's natural regulatory capacity. The projected hydrological shifts indicate a future defined by extreme variability: severe dry-season flow deficits revealing critically diminished baseflow and groundwater recharge evidenced by declines exceeding 60% in November and 52.91% in December. This scarcity is contrasted by a sharp, short-lived amplification of peak flows (a 52.83% surge in August), indicating a transformation into a flashier system primarily driven by increased surface runoff from the degraded landscape. The study provides quantitative evidence that LULC change is the primary driver of increased flood flashiness and water scarcity, posing significant threats to water security, domestic supply, and ecological health. Consequently, this research validates that proactive, scenario-based hydrological modeling is an indispensable tool for designing adaptive land use governance and conservation policies aimed at mitigating future hydrological stress in the Moiben River watershed.