Distributed model of hydrological and sediment transport processes in large river basins in Southeast Asia

Abstract

Abstract. Soil erosion and sediment transport have been modeled at several spatial and temporal scales, yet few models have been reported for large river basins (e.g., drainage areas > 100 000 km2). In this study, we propose a process-based distributed model for assessment of sediment transport at a large basin scale. A distributed hydrological model was coupled with a process-based distributed sediment transport model describing soil erosion and sedimentary processes at hillslope units and channels. The model was tested on two large river basins: the Chao Phraya River Basin (drainage area: 160 000 km2) and the Mekong River Basin (795 000 km2). The simulation over 10 years showed good agreement with the observed suspended sediment load in both basins. The average Nash–Sutcliffe efficiency (NSE) and average correlation coefficient (r) between the simulated and observed suspended sediment loads were 0.62 and 0.61, respectively, in the Chao Phraya River Basin except the lowland section. In the Mekong River Basin, the overall average NSE and r were 0.60 and 0.78, respectively. Sensitivity analysis indicated that suspended sediment load is sensitive to detachability by raindrop (k) in the Chao Phraya River Basin and to soil detachability over land (Kf) in the Mekong River Basin. Overall, the results suggest that the present model can be used to understand and simulate erosion and sediment transport in large river basins.

Did the Construction of the Bhumibol Dam Cause a Dramatic Reduction in Sediment Supply to the Chao Phraya River?

“…Damming is one of the possible causes of sediment load reduction in many rivers worldwide [1,7,9,31,[59][60][61][62]. The Bhumibol Dam on the Ping River and the Sirikit Dam on the Nan River was estimated to cause a 75-85% sediment reduction to the CPR system.…”

Empirical Sediment Transport Models Based on Indoor Rainfall Simulator and Erosion Flume Experimental Data

“…Difficulties in the calibration and validation stages of models are other issues to be considered (Aksoy, ). Despite of all these challenges and difficulties, sediment transport models developed at hillslope and watershed scales (Zhang et al, ; Aksoy & Kavvas, ; Arguelles et al, ; Zuliziana et al, ) have enhanced the understanding of the mechanism of sediment transport under varying conditions over the hillslope or watersheds. When the GIS technology is combined with the sediment transport modelling, it is possible to derive an effective way to map spatial distribution of soil erosion risks in large areas to be used in assisting conservation management and land use planning (Mandal & Sharda, ; Dai et al, ).…”

Effects of Dam Construction in the Wang River on Sediment Regimes in the Chao Phraya River Basin

“…Impacts of large dam construction on significant reduction in riverine sediment supply from many rivers to the ocean have been intensively reported during the past decades [7,47,[66][67][68][69][70][71]. In Thailand, many studies suggested a 75-85% sediment reduction in the CPR system due to the Bhumibol Dam in the Ping River and the Sirikit Dam in the Nan River, resulting in severe coastal erosion in the upper Gulf of Thailand.…”