Present and Future Hydrological Response to Land Use and Climate Change in the Jhikhukhola Watershed in Nepal

The alteration of land use and land cover (LULC) has become a global environmental concern, significantly affecting land and water resource management. In many developing nations, population growth and uncontrolled urbanization are key drivers of LULC changes. This study examines the impact of LULC changes on surface outflow and evapotranspiration in the Jhikhukhola watershed, Nepal, over the past three decades using the Soil and Water Assessment Tool (SWAT) model. LULC changes were analyzed at decadal intervals from 1990 to 2020. The findings revealed a notable increase in agricultural land, with growth rates reaching up to 15% per decade, along with substantial expansion of built-up areas. This shift has led to a reduction in green areas, such as bushlands, forests, and grasslands, which declined by as much as 19% per decade in the study region. Additionally, LULC changes were accompanied by a reduction in rainfall and a consistent annual increase in temperature, averaging 6.192 mm and 0.0679°C per year, respectively. Projections using the SWAT model and Global Climate Models indicate a continued moderate rise in temperature and slight decreases in rainfall and evapotranspiration in the future. These findings highlight the need for effective water management and urban planning strategies to address the impacts of rapid urbanization and climate change on water availability.