Spatial and temporal changes in runoff and sediment loads of the Lancang River over the last 50 years

Response of Sediment Load to Hydrological Change in the Upstream Part of the Lancang-Mekong River over the Past 50 Years

“…Given the better correlations of runoff and PF with sediment load, the operation of dams could play an important role in the sediment load change through (extreme) runoff regulation in the upstream part of the Lancang-Mekong River. Figure 6 indicates that, at the 99% confidence level, the annual LF had nonsignificant negative correlation with sediment load over the past 50 years (Figure 6b), and the correlation was weaker than that of PF (Figure 6a Overall, the increasing trend in sediment load agrees with prior search [41][42][43][44][45], and based on the significant increasing trend of runoff and its significant positive correlation with sediment load, it can be inferred that the increase of sediment load could be mainly attributed to the increase of runoff caused by slight increase of precipitation and land cover change (i.e., from arable and Overall, the increasing trend in sediment load agrees with prior search [41][42][43][44][45], and based on the significant increasing trend of runoff and its significant positive correlation with sediment load, it can be inferred that the increase of sediment load could be mainly attributed to the increase of Overall, the increasing trend in sediment load agrees with prior search [41][42][43][44][45], and based on the significant increasing trend of runoff and its significant positive correlation with sediment load, it can be inferred that the increase of sediment load could be mainly attributed to the increase of runoff caused by slight increase of precipitation and land cover change (i.e., from arable and forested land to construction land since the mid-1980s in Yunnan [22]) in the upstream part of the Lancang-Mekong River since 1980.…”

“…Considerable research has been conducted on how factors control sediment yield in a basin (e.g., land use change [7], land slopes [8], weather types [9], and precipitation or other climatic variables change [10][11][12][13][14]), the spatial-temporal change of sediment concentration and Runoff-Sediment Relationship (RSR) [15,16], and the scale effect of RSR [17][18][19]. These studies provided important trend data and are useful for understanding sediment rich water energy resources [22,27]. The study area is the upstream part of the Lancang-Mekong River from the Jiuzhou Station in Yunnan Province, involving 15 planned cascade hydroelectric dams ( Figure 1).…”

“…Water 2017, 9, x FOR PEER REVIEW 3 of 14 cascade hydroelectric dams have been completed along the main river channel to utilize its extremely rich water energy resources [22,27]. The study area is the upstream part of the Lancang-Mekong River from the Jiuzhou Station in Yunnan Province, involving 15 planned cascade hydroelectric dams ( Figure 1).…”

Spatiotemporal variations of suspended sediment transport in the upstream and midstream of the Yarlung Tsangpo River (the upper Brahmaputra), China

“…Sediment transport regimes in the large rivers originated on the Tibetan plateau, such as the Yellow, the Yangtze, the Indus, and the Ganges-Brahmaputra Rivers, have received increasing attention because of the drastic changes (Lu, 2004). In the Mekong River, an extremely important international river flowing across six Asian countries, the temporal variation of sediment load was not consistent with changes in the water discharge (Wang et al, 2011;Zhai et al, 2016), which was attributed to soil disturbance and sediment trapping due to dam construction (Wang et al, 2011). The Yangtze River, ranked as the 5th largest globally in terms of discharge and sediment load, also experienced a drastic reduction in sediment load (Yang et al, 2011;Dai and Lu, 2014).…”

“…The upper river basin was reported to be the main sediment source for the Yangtze River (Lu and Higgitt, 1999;Lu, 2004;Wang et al, 2007b), while significant deposition occurred in the midstream and downstream (Chen et al, 2001;Yang et al, 2007aYang et al, , 2007bWang et al, 2007b). In the Mekong River, an extremely important international river flowing across six Asian countries, the temporal variation of sediment load was not consistent with changes in the water discharge (Wang et al, 2011;Zhai et al, 2016), which was attributed to soil disturbance and sediment trapping due to dam construction (Wang et al, 2011). Wang et al (2011) identified the largest sediment source area above Chiang Saen and the largest sediment sink between Luang Prabang and Nong Khai.…”