Most of studies on sediment dynamics in stable shallow lakes focused on the resuspension process as it is the dominant process. However, understanding of sediment dynamics in a shallow lake influenced by flood pulse is unclear. We tested a hypothesis that floodplain vegetation plays as a significant role in lessening the intensity of resuspension process in a shallow lake characterized by the flood pulse system. Therefore, this study aimed to investigate sediment dynamics in this type of shallow lake. The target was Tonle Sap Lake (TSL), which is a large shallow lake influenced by a flood pulse system of Mekong River located in Southeast Asia. An extensive and seasonal sampling survey was conducted to measure total suspended solid (TSS) concentrations, sedimentation and resuspension rates in TSL and its 4 floodplain areas. The study revealed that sedimentation process was dominant (TSS ranged: 3-126mgL) in the high water period (September-December) while resuspension process was dominant (TSS ranged: 4-652mgL) only in the low water period (March-June). In addition, floodplain vegetation reduced the resuspension of sediment (up to 26.3%) in water. The implication of the study showed that resuspension is a seasonally dominant process in shallow lake influenced by the flood pulse system at least for the case of TSL.

Tonle Sap Lake (TSL) in Cambodia is the largest freshwater body in South‐East Asia and one of the most productive ecosystems in the world. The lake and its ecosystems are widely under threat, however, due to anthropogenic activities occurring inside and outside its basin (e.g., water infrastructure development; land use change), being poorly understood in most aspects. This study provides an updated review of the state of knowledge of the TSL ecosystem, as well as important research directions for sustainable lake environmental management of Tonle Sap Lake by focusing on four major topics, including climate change and hydrology, sediment dynamics, nutrient dynamics and primary and secondary production. The findings of this study suggest anthropogenic activities in the TSL basin, as well as the Mekong, in combination together with climate changes, are key contributing factors in the degradation of the TSL ecosystem. Insufficient accurate data, however, precludes quantitative assessment of such impacts, making it difficult to quantitatively assess and accurately understand the ecosystem process in the lake ecosystem. More efforts are recommended in regard to environmental monitoring in all sub‐basins around TSL, assessing seasonal changes in nutrient and sediment inputs corresponding to water level and flow changes, assessing cumulative impacts of water infrastructure and climate change on the ecosystem dynamics, and elucidation of ecosystem processes within the lake's internal system.

An integrated hydrological-hydraulic model employing the 2-D local inertial equation as the core is established for effective numerical simulation of surface water flows in a great lake and its floodplain. The model is a cascade of validated hydrological and hydraulic sub-models. The model was applied to simulating the surface water flows of the Tonle Sap Lake and its floodplain in Cambodia using the roughness coefficient value calibrated comparing with a remote-sensing data set. The resulting model reasonably handles backwater flows during the rainy season and simulates the propagations of wet and dry interfaces without numerical instability, owing to a proper setting of time step supported by a novel numerical stability analysis. Sensitivity analysis of the surface water dynamics focusing on the setting of roughness coefficient and the backwater effect was also carried out. Overall, utilizing the 2-D local inertial equation in the assessment of lake water dynamics is a new modelling approach, which turns out to be an efficient simulation tool.