Water balance estimation and runoff simulation of Chameliya Watershed, Nepal

Sustainable water resource management has become increasingly challenging due to the limited availability of hydrometeorological data in remote mountainous areas, making it difficult to assess water balance and simulate runoff at various spatiotemporal scales. This study aims to assess the 30-year (1990–2019) water balance of the Chameliya Watershed in the Mahakali River Basin, Nepal, with a focus on glacier dynamics, utilizing the Spatial Process in Hydrology (SPHY) modeling tool. The data analysis disclosed that the watershed experienced positive water balance for 6 months, primarily during the monsoon season, while the remaining months exhibited negative values. Additionally, a comparison between the recent decade (2010–2019) and the late 1990s revealed an increase in hydrological components, such as discharge and precipitation, alongside a decrease in evapotranspiration and glacier melt. The dynamics of discharge disclose fluctuations among multiple contributors, with rainfall taking precedence, followed by baseflow, snowmelt, and glacier melt in descending sequence. Overall, the study offers a profound understanding of water availability in the Chameliya Watershed and highlights its dynamic changes over the study period. This knowledge holds great significance, especially in remote, inaccessible, and high-altitude regions. It also underscores the necessity of understanding Himalayan hydrological dynamics for precise flood prediction, climate risk assessment, and sustainable resource management amid global climate change.