Changes in water balance across climate zones of Vietnam over the past four decades

Abstract

Abstract In a warming climate, it is important to understand the characteristics and changes in major components of the water balance. This information is crucial to countries spanning over multiple climate zones such as Vietnam, as such understanding will ensure new water policies are designed and implemented appropriately to support sustainable development. Long-term observations of the major components of the water cycle (i.e., precipitation, evapotranspiration, and runoff), however, are usually unavailable for many regions of the world, including Vietnam, making it challenging to obtain a holistic perspective on large-scale features of water resources. To address this challenge, this study selected seven catchments of Vietnam that have varying climate characteristics (each represents a climate zone of Vietnam) and developed a hydrological model for each of the assessed catchments. The models showed satisfactory performance (the Nash-Sutcliffe efficiency ranges from 0.53 to 0.9 and a percentage bias ranging from -15.1 to 19.4) and were able to reproduce the heterogeneous pattern of hydro-climate conditions across Vietnam. Long-term changes (from 1980 to 2019) in simulated water balance components were then assessed to provide a new perspective on changes in the water cycle across Vietnam in the last four decades.