Impact of Future Climate and Development on Agricultural Water Management: A Case Study of the Huai Sat Bat Sub-basin in Northeastern Thailand

In this study, we used the Water Evaluation And Planning (WEAP) model to provide a participatory framework to outline choices (and consequences) for river managers, stakeholders and policy makers. The water balance was created for the data-limited Huay Sai Bat (HSB) sub-basin located in northeastern Thailand. Leveraging the involvement of stakeholders, we developed an appropriate representation of the catchment hydrology utilizing the best available data. In addition, WEAP allowed for simulation of impacts from alternative scenarios of climate change, land-use development and water resource management in HSB. These scenarios were developed iteratively across several participatory exercises. Our modeling results indicate that regional climatic changes tend to increase streamflow during the wet (monsoon) season while land-use and management changes only had minor impacts on streamflow. However, the scenarios of land-use and management changes, specifically those reflecting increases in irrigated rice and sugarcane production and/or shifts toward small-scale or regional irrigation schemes, lead to relatively large unmet water demands (particularly during the dry season). In addition, and perhaps more importantly, the WEAP modeling facilitated communication with stakeholders across various management levels, allowing for assessment of the main concerns surrounding ongoing and future potential changes in HSB. The outcomes of these interactions were then used to formulate recommendations addressing potential gaps between policy and implementation. The study indicates that a participatory modeling approach is a promising way of incorporating problem-relevant knowledge and values of stakeholders to influence decisions as well as strengthen civic capacity.