Homogenization and polarization of the seasonal water discharge of global rivers in response to climatic and anthropogenic effects

Chai, Yuanfang; Liu, Caiqiong; Zhang, Lin; Miao, Chiyuan; Borthwick, Alistair G. L.; Zhu, Boyuan; Li, Yitian; Dolman, A. J.

doi:10.1016/j.scitotenv.2019.136062

Cited by 24 publications

(25 citation statements)

References 57 publications

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“…In Fig. 1a, we investigate whether such a relation exists in the observations by plotting the interannual variability of the surface air temperature and dry season precipitation from 1 May to 31 October 22,23 for the sector of Amazonia bounded by 75°-45°W and 15°-0°S using the observational data from the HadCRUT4 data set. The observed temperature is near completely anticorrelated the dry season precipitation record; this relation (y = (−0.58 ± 0.16)x, p < 0.001, R = 0.45) is also significant in Fig.…”

Section: Physical Mechanisms Of Emergent Constraintmentioning

confidence: 99%

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

et al. 2021

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The complete or partial collapse of the forests of Amazonia is consistently named as one of the top ten possible tipping points of Planet Earth in a changing climate. However, apart from a few observational studies that showed increased mortality after the severe droughts of 2005 and 2010, the evidence for such collapse depends primarily on modelling. Such studies are notoriously deficient at predicting the rainfall in the Amazon basin and how the vegetation interacts with the rainfall is poorly represented. Here, we use long-term surface-based observations of the air temperature and rainfall in Amazonia to provide a constraint on the modelled sensitivity of temperature to changes in precipitation. This emergent constraint also allows us to significantly constrain the likelihood of a forest collapse or dieback. We conclude that Amazon dieback under IPCC scenario RCP8.5 (crossing the tipping point) is not likely to occur in the twenty-first century.

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Section: Physical Mechanisms Of Emergent Constraintmentioning

confidence: 99%

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

et al. 2021

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“…Disturbances caused by human activities tend to accelerate or modify natural processes, shortening the timescale of river channel adjustment (Rinaldi & Simon, 1998). River dams have particularly altered original water and sediment transport processes, resulting in downstream changes (scouring and water level adjustment) to counter impacts such as flow variation and sand loss (Draut et al, 2011;Fang et al, 2012;Moretto et al, 2014;Smith et al, 2016;Wang et al, 2016;Yang et al, 2017bYang et al, , 2018bYang et al, , 2018cChai et al, 2020b).…”

Section: Introductionmentioning

confidence: 99%

Impact of the Three Gorges Dam on riverbed scour and siltation of the middle reaches of the Yangtze River

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Zheng

Zhang

et al. 2022

Earth Surf Processes Landf

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This study investigated the influence of the Three Gorges Dam (TGD) on the evolution of nearby channels in the Yangtze River (Changjiang River) system in order to better understand the environmental impact of large‐scale reservoir operations. From 2003 to 2017, the amounts of runoff and sediment transport in the Yangtze River were reduced by 3.3–14.5% and 67.8–92.7%, respectively, relative to 1955–2002 before the TGD was operational. Topographic measurements of the middle reaches (Yichang to Hukou) of the Yangtze River were analyzed from 1975 to 2017, during which time the cumulative erosion of the flood channel was 22.78 × 108 m3, and the dry channel accounted for 90.3% of the erosion. Following commissioning of the TGD, the scouring intensity of the sandy gravel section near the dam initially increased then decreased, whereas the scouring intensity of sandy sections away from the dam continued to increase. Beaches on convex banks of curved sections were scoured, and deep channels on concave banks became silted. In braided sections, the braids tended to shrink, and the diversion ratio of the main branch during dry seasons reduced, resulting in frequent branch alternation. Compared to changes in the downstream river channels of other large reservoirs worldwide, scouring from the TGD is extensive. The findings of this study are significant for river channel regulation and waterway planning in the Yangtze River and worldwide.

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“…Recent studies indicated that nitrogen cycle, mainly driven by microbial processes (Knoll et al., 2012 ), is strongly influenced by the hydrological conditions of water bodies (Wang et al., 2010 ; Xia et al., 2017 ; Yu et al., 2019 ). Since the stability of nitrogen cycle is a key indicator to aquatic health (Reaver et al., 2021 ), linking the nitrogenous substances in nitrogen cycling with hydrological variations have been concerns of many studies for the environmental health of water bodies in different forms (Abdul‐Aziz & Ahmed, 2017 ; Schrag, 2017 ), especially considering that substantial changes in discharge and sediment transport have widely occurred in global rivers (Chai et al., 2020 ; Li et al., 2020 ).…”

Section: Introductionmentioning

confidence: 99%

“…Chai et al. ( 2020 ) found that allocation of water discharge between dry and flood seasons had been homogenized along the entire reach of the Yangtze River. Zhang et al.…”

Section: Introductionmentioning

confidence: 99%

Stability of Aquatic Nitrogen Cycle Under Dramatic Changes of Water and Sediment Inflows to the Three Gorges Reservoir

et al. 2022

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Stability of nitrogen cycle is a key indicator to aquatic health. In recent years, water and sediment inflows to the Three Gorges Reservoir (TGR) have changed significantly. To reveal the effects of such dramatic hydrological changes on aquatic nitrogen cycle, this paper at first analyzed the changing trends of water and suspended sediment discharges of TGR based on dynamic harmonic regression, and found that the intra‐year distribution of water flow was significantly homogenized between flood and dry seasons, with the seasonal variations narrowed by 43.5%–69.9% during 2007–2016, while sediment concentration sharply dropped (the non‐periodic term decreased by 1.48%–2.07%/month). Modified with the effects of sediment concentration variations on nitrification/denitrification rates, the proposed numerical model surprisingly showed that ammonia nitrogen and total nitrogen concentrations in TGR were insensitive to either water flow homogenization or sediment reduction, implying relative stability of microbial community related to nitrogen cycle, which is a positive sign for aquatic health. However, N 2 emission varied more violently. The variation range of nitrogen gas (N 2 ) emitted from TGR enlarged by 30% with the homogenization of water inflow from 2010 to 2016, while the annual total N 2 emission decreased by 7% due to the reduction of sediment concentration, indicating quick response and strong adaption of the microbial N 2 producing process to the environmental changes of TGR, which is beneficial for maintaining ecological functions related to nitrogen cycling. This work helps understanding nitrogen cycle of reservoirs experiencing dramatic changes in water and sediment inflows.

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Homogenization and polarization of the seasonal water discharge of global rivers in response to climatic and anthropogenic effects

Cited by 24 publications

References 57 publications

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

Impact of the Three Gorges Dam on riverbed scour and siltation of the middle reaches of the Yangtze River

Stability of Aquatic Nitrogen Cycle Under Dramatic Changes of Water and Sediment Inflows to the Three Gorges Reservoir

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