Abstract
River water temperature is one of the major factors in river ecology and water use. Mixture of water between river channels and floodplains affects river water temperature. In addition, the spread of shallow water causes an increase in water covered areas and retention time, which leads to an increase in heat exchange between the atmosphere and soil, and in transmission of radiation, which leads to a change the heat budget. In this study, we developed a river water temperature model by solving the energy balance with consideration of the changes of surface water area in order to evaluate these effects. We combined it with a river flow model and validated river discharge, heat budget and water temperature using in-situ observation data in Thailand. We also assessed the impacts with and without considering inundation area.
