Rapid channel incision of the lower Pearl River (China) since the 1990s as a consequence of sediment depletion

Lu, Xixi; Zhang, S. R.; Xie, Shuguang; K., P.

doi:10.5194/hess-11-1897-2007

Cited by 97 publications

(47 citation statements)

References 32 publications

(32 reference statements)

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“…Before mid-1980s, however, the scouring and filling processes of the river channels are in dynamic balances or in slight deposition processes. The river channels in the lower Pearl River basin were greatly altered due to in-channel dredging and levee construction after about mid-1980s, resulting in decreasing water level (Lu et al, 2007). Lu et al (2007) also indicated that slight increase in water discharge and significant decrease in sediment load since the early 1990s in both the West River and North River also likely contributed to the observed dramatic river bed downcutting to some extent.…”

Section: Discussionmentioning

confidence: 96%

“…Massive incision of river channel has caused a significant change in channel geometry. Lu et al (2007) showed notable increases in the cross-section area accompanying the downcuts of river channels at all the Gaoyao station, Makou station and the Sanshui station. Based on the time when the shifts of the double mass curves start at the stations in the West River and North River, i.e.…”

Section: Discussionmentioning

confidence: 99%

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Changing properties of hydrological extremes in south China: natural variations or human influences?

Qiang

Jiang

Chen

et al. 2010

Hydrological Processes

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Abstract:Extreme events are drawing increasing concerns in recent decades due to their catastrophic nature. In this case, we thoroughly analysed the statistical behaviours of hydrological extremes in the south China by taking Guangdong province as a case study because of its unshakable position in the economic development in China. Our results further corroborated the fact that the hydrological changes are the integrated consequences of various external factors, basically the human activities and climate changes. Generally, decreasing annual maximum water (AMW) level was observed mainly in the seaward regions characterized by decreasing occurrence frequency of higher AMW level. Streamflow variations are influenced mainly by precipitation changes. Increasing annual maximum streamflow (AMS) can be attributed to the increasing precipitation intensity in recent years. However, in the East River basin, hydrological regulation function of the water reservoirs greatly reduced the AMS. In the lower East River, however, downcutting river channel and notable increases in the cross-section area caused larger magnitude of decrease in AMW level when compared to AMS. The time when the relations between AMW level and streamflow start to change matches well the time when massive in-channel sand dredging occurred, showing tremendous influences of human activities on hydrological processes in the lower Pearl River basin. This study will be of great scientific and practical merits in better understanding the statistical behaviours of hydrological extremes under the changing environment and also help to improve human mitigation to natural hazards in south China.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Changing properties of hydrological extremes in south China: natural variations or human influences?

Qiang

Jiang

Chen

et al. 2010

Hydrological Processes

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show abstract

“…On the other hand, the estimated 870 million cubic metres of sand excavated between 1986 and 2003 in the rivers of the Pearl basin resulted in severe lowering of river channels, bank instability and threats to infrastructure, changes in the divided flow ratio between various water courses, modification of saltwater intrusion levels and a limitation of the freshwater supply. The extraction rate was much greater than the replenishment rate, a situation aggravated because sediment fluxes depleted dramatically due to the combined effects of declining rainfall, dam construction, water diversion, reforestation and afforestation (Lu et al, 2007, Luo et al, 2007.…”

mentioning

confidence: 99%

Geography of Sand and Gravel Mining in the Lower Mekong River

Bravard¹,

Goichot²,

Gaillot³

2013

echogeo

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“…Therefore, the currently agreed minimum flow requirements at Wuzhou and Sixianjiao may not be sufficient to combat salt intrusion in the future. Moreover, channel incision can contribute to saltwater intrusion and subsequent water shortage in the delta due to increasing channel depth and sea level (Lu et al, 2007). The rapid channel incision was mainly the result of extensive sand mining in the lower reaches of the Pearl River.…”

Section: Q2: Can Water Allocation Reduce Saltwater Intrusion In the Pmentioning

confidence: 99%

Water allocation under future climate change and socio-economic development : the case of Pearl River Basin

Yan¹

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Water shortage has become a major challenge in many parts of the world due to climate change and socio-economic development. Allocating water is critical to meet human and ecosystem needs in these regions now and in the future. However, water allocation is being challenged by uncertainties associated with climate change and socio-economic development. This thesis aims to assess the combined effects of climate change and socio-economic development on water supply and demand in the Pearl River Basin (PRB) in China, and identify water allocation plans, which are robust to future climate change and socio-economic development. To do so, the impact of climate change on future water availability is first assessed. Next, different model frameworks are developed to identify robust water allocation plans for improving reservoir management, ensuring sufficient flow into the delta to reduce salt intrusion, and providing sufficient freshwater for human and industrial consumption under future climate change and socio-economic development. Results show that water availability is becoming more variable throughout the basin due to climate change. River discharge in the dry season is projected to decrease throughout the basin. For a moderate climate change scenario (RCP4.5), low flows reduce between 6 and 48 % depending on locations. For a high climate change scenario (RCP8.5), the decreases of low flows can reach up to 72%. In the wet season, river discharge tends to increase in the middle and lower reaches and decreases in the upper reach of the Pearl River Basin. The variation of river discharge is likely to aggravate water stress. Especially the reduction of low flow is problematic as already the basin experiences water shortages during the dry season in the delta. The model frameworks developed in this study not only evaluate the performance of existing water allocation plans in the past, but also the impact of future climate change on robustness of previous and newly generated water allocation plans. The performance of the four existing water allocation plans reduces under climate change. New water allocation plans generated by the two model frameworks perform much better than the existing plans. Optimising water allocation using carefully selected state-of-the-art multi-objective evolutionary algorithms in the Pearl River Basin can help limit water shortage and salt intrusion in the delta region. However, the current water allocation system with six key reservoirs is insufficient in maintaining the required minimum discharge at two selected gauge stations under future climate change. More reservoirs, especially in the middle and lower reaches of the Pearl River, could potentially improve the future low flow into the delta. This study also explored future water shortage in the Pearl River Basin under different water availability and water use scenarios. Four different strategies to allocate water were defined. These water allocation strategies prioritize upstream water use, Pearl River Delta water use, irrigation wa...

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Rapid channel incision of the lower Pearl River (China) since the 1990s as a consequence of sediment depletion

Cited by 97 publications

References 32 publications

Changing properties of hydrological extremes in south China: natural variations or human influences?

Changing properties of hydrological extremes in south China: natural variations or human influences?

Geography of Sand and Gravel Mining in the Lower Mekong River

Water allocation under future climate change and socio-economic development : the case of Pearl River Basin

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