Effects of different management approaches on unmet water demand in coffee-producing areas during wet and dry years: a case study of the Srepok River Watershed, Vietnam

The primary cause of conflicts over water allocation is growing demand and limited supply, which has become an increasingly serious issue in many watersheds. To alleviate water disputes, effective management strategies can be employed, particularly in the context of intensifying agricultural production and unpredictable changes in weather. In this study, two models, SWAT and WEAP, and the modified surface water supply index (MSWSI) were utilized to evaluate water allocation in the Srepok River Watershed (SRW), considering the prioritization of demand and various irrigation methods, during both wet and dry years. The crop irrigation was chosen to be the main focus in relation to the unmet water demand (UWD). The results indicated that coffee was the primary cause of UWD in the middle of the watershed during the second half of the dry season, and annual crops (AC) were the secondary cause. This research further elucidated that while prioritizing demand had an insignificant impact, transitioning from hose irrigation to sprinkler irrigation could be remarkably effective in mitigating the issues of UWD in coffee crops during both wet and dry years.