Impact of Land Use Change on Hydrological Responses in the Jongkok–Meninring–Babar (JMB) Watershed, Lombok Island, Indonesia

Lombok Island, covering 4,672 km2 with a population of about three million, is a popular tourist destination yet highly vulnerable to environmental degradation driven by rapid tourism and settlement expansion. This study investigates the impact of land use change on hydrological response using the SWAT model. Land use dynamics were analyzed through satellite image classification, revealing that most urban growth in Mataram City has replaced paddy fields, while in upstream areas it has encroached on plantations and agricultural land. Model calibration and validation achieved Nash-Sutcliffe Efficiency (NSE) values of 0.66 and 0.55, respectively, indicating acceptable performance. The simulation results from 1995 to 2017 show significant hydrological alterations: surface runoff increased by 33.1 mm/year, while base flow and deep aquifer recharge declined by 12.3 mm/year and 12.5 mm/year, respectively. These findings highlight the adverse effects of urban expansion on the island's water resources, emphasizing the need for sustainable land use planning to balance development and environmental protection.