Response of runoff and suspended load to climate change and reservoir construction in the Lancang River

Abstract

With the operation of six cascade reservoirs, the flow regime and sediment discharge of the Lancang River have changed greatly. The changes of runoff and suspended load have attracted extensive attention. The hydrological data of Gajiu and Yunjinghong stations in Lancang River from 1964 to 2019 were analyzed by using wavelet analysis, double mass curve and abrupt change analysis. The temporal trends in runoff and suspended load were evaluated. Results revealed that the reduction of suspended load was much more profound than the change of runoff. There was a slight downward trend in annual runoff due to climate change. After the completion of Xiaowan and Nuozhadu reservoirs, the proportion of runoff in flood season decreased by 22.64 and 30.75%, respectively. Wavelet analysis was used to reveal the characteristics of runoff evolution. With the operation of reservoirs, suspended load appeared abrupt changes in 1993 and 2008. The amount of suspended load during 2009–2019 decreased by 95.47–98.78% compared with that before the reservoir construction. This paper presents the latest quantitative study on the temporal variation of runoff and suspended load since the completion of Xiaowan and Nuozhadu reservoirs, which is of great importance for guiding the operation of reservoirs and maximizing the value of the whole Lancang-Mekong River basin.

Proglacial river sediment fluxes in the southeastern Tibetan Plateau: Mingyong Glacier in the Upper Mekong River

“…However, the high sediment supply from the proglacial catchments in the headwater region cannot be transported downstream because of the series of cascade dams constructed in the Upper Mekong River. The sediment load below these cascade dams in Yunnan has dropped to around 10% of the pre‐dam level (Chua & Lu, 2022a, 2022b; Sun et al, 2022). Subsequently, the problem of sediment starvation due to the trapping of sediment by reservoirs will get worse in the future with more dams being planned or built.…”

“…However, the high sediment supply from the proglacial catchments in the headwater region cannot be transported downstream because of the series of cascade dams constructed in the Upper Mekong River. The sediment load below these cascade dams in Yunnan has dropped to around 10% of the pre-dam level (Chua & Lu, 2022a, 2022bSun et al, 2022).…”

Proglacial river sediment fluxes in the south-eastern Tibetan Plateau: Ming Yong Glacier in the Upper Mekong River

“…However, the high sediment supply from the proglacial catchments in the headwater region cannot be transported downstream because of the series of cascade dams constructed in the Upper Mekong River. According to Sun et al (2022), the sediment load below these cascade dams in Yunnan has dropped to around 10% of the pre-dam level. Subsequently, the problem of sediment starvation due to the reservoirs trapping will get worse in future with more dams being planned or built.…”

An Estimation Method of River Dry Runoff Alteration after Upper New Reservoirs Storage

“…Various hydrological datasets spanning several decades have been utilized, employing different regression models, wavelet methods, and other techniques to analyze the aforementioned impacts [14]. Downstream runoff exhibits close variability with meteorological variables and is significantly influenced by dam construction [15]. However, the long-term average runoff over multiple decades can encompass the combined effects of climate change.…”