Modelling inundation patterns and sediment dynamics in the extensive floodplain along the Tonle Sap River

Abstract

AbstractThe Tonle Sap River (TSR) serves as a natural medium for the reversal flow between Tonle Sap Lake (TSL) and the Mekong River to sustain productivity and biodiversity in the TSR floodplain and TSL. Understanding the hydrological connectivity and its dynamics in the TSR, including its floodplain, is therefore important to support activities that aim to maintain ecological services in the TSR–TSL system. Thus, the main objective of this study is to examine the hydrological connectivity of the TSR and its floodplain by a modelling approach that integrates inundation patterns and sediment dynamics. The Caesar–Lisflood model was applied to describe inundation, sediment erosion, transport, and deposition in the TSR for the period of 2003–2013. The inundation areas connected to the TSR ranged from 140 to 2,327 km2, whereas the isolated inundation areas from the TSR ranged from 0.27 to 504 km2. Sediment dynamics showed its influence on inundation patterns and hydrological connectivity and could alter the yearly inundation ratio (defined as a normalized inundation frequency with a value ranging from 0 to 1) up to 0.8. Our approach provides a quantitative way to determine key factors (e.g., total inundation areas, seasonality, and connectivity of inundation patterns) for further investigation of ecological processes in relation to the inundation patterns and sediment dynamics in the TSR and TSL.