Modeling drought hazard and risk in changing climate: the case of Cai-Phan Rang River Basin in the South-Central coast of Vietnam

Drought is a naturally occurring event associated with a significant decrease in water availability over a region. Changes in hydrological conditions in the area, such as climatic changes, particularly in rainfall patterns, can trigger droughts and other natural disasters, which have substantial negative impacts on both human life and the environment. This study aims to model drought hazards and risks and then find their effects on forestry and agriculture in the context of climate change, which has become increasingly evident in recent years in the Cai-Phan Rang River Basin. Various methods exist for identifying and quantifying drought, and this study focuses on a combined assessment that takes into account both meteorological and hydrological aspects. This combined approach relies on the calculation of the drought meteorological index (SPI) and employs the hydrological model (SWAT model) as a fundamental tool for assessment. Subsequently, in conjunction with understanding the responses and adaptability of the local people, propose additional solutions that can help bridge the gap between policy objectives and on-ground realities. The results of the analysis of climate characteristics show an increasing trend of both temperature and rainfall increases, the rainy season tends to come later and shorter than before, with a prolonged period of lack of rain causing drought. Along with that, there are periods of decline in flow, surface water and water yield in the entire river basin, corresponding to the periods of drought occurrence. Analysis results of drought characteristics show that drought hazards are becoming more serious. Combined. all results led to a high risk of drought in the CPR river basin, ranging from moderate to very high. Although many programs and solutions have been implemented in the short and long term, drought still brings serous losses in the study area. Therefore, it is necessary to have more useful solutions to help minimize and adapt to drought. The results derived from this research can offer valuable insights and approaches that may be applicable to other basins and serve as a useful resource for managers and decision-makers involved in integrated river basin management in Vietnam.