Longitudinal transport timescales in a large dammed river - The Changjiang River

Sun, Jizhou; Xiao, Zijun; Yuan, Botao; Zhang, Xiaofeng

doi:10.1016/j.scitotenv.2020.144886

Cited by 13 publications

(4 citation statements)

References 37 publications

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“…The central area of the reservoir is a transition zone with low water velocity and long residence time [63]. A long residence time indicates that the amount of water entering or leaving the river flow into the central area of reservoir is relatively small [64]. Residence time is a period when the sediment particles are temporarily in a water storage [65].…”

Section: Carlson's Tsimentioning

confidence: 99%

Utilizing Satellite Imagery for Seasonal Trophic Analysis in the Freshwater Reservoir

Rachmadita,

Widiana,

Rahmat

et al. 2023

J. Multidiscip. Appl. Nat. Sci.

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Eutrophication, an aquatic problem that impacts water quality and ecosystems, can be addressed through technological developments utilizing satellite imagery to analyze the trophic status of water. This study aimed to determine the trophic status of the freshwater reservoir in different seasons using satellite imagery. Water quality data were obtained from field surveys (11 samples) during the wet and dry seasons in Cirata Reservoir (Indonesia) while the remote sensing images were obtained from the Landsat-8 OLI. Trophic status refers to Carlson's Trophic State Index consisting of two parameters named chlorophyll-A and water transparency. This study found that satellite imagery could estimate seasonal trophic information. During the wet season, the algorithms determined information about chlorophyll-A (48%) and transparency (35%). Whereas during the dry season, the algorithms successfully estimated both information at 59% and 21%, respectively. Unfortunately, the Landsat-8 OLI had limitations for estimating total phosphorus. From these two parameters, the trophic status in the Cirata Reservoir showed moderate (wet season) and mild (dry season) eutrophic. Cirata Reservoir has a higher trophic level during the wet season since it has more surface water supply with lots of pollutants.

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Section: Carlson's Tsimentioning

confidence: 99%

Utilizing Satellite Imagery for Seasonal Trophic Analysis in the Freshwater Reservoir

Rachmadita,

Widiana,

Rahmat

et al. 2023

J. Multidiscip. Appl. Nat. Sci.

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“…The constructions of dams and reservoirs not only changed the hydrological regimes in the Changjiang River, but also changed the inherent water chemistry (Ye et al, 2007;Xu et al, 2009) and phytoplankton dynamics (Zeng et al, 2006). For example, during dry seasons, water storage in the reservoirs will prolong water residence time (Sun et al, 2021), making the river ecosystem more like a lake ecosystem. During flood seasons, however, the Changjiang River was more like a real river https://doi.org/10.5194/egusphere-2022-30 Preprint.…”

Section: Potential Factors Influencing Organic Matter Quantity and Qu...mentioning

confidence: 99%

“…In addition, POC and DOC dynamics might also be changed by these constructions. This is because on one hand, the prolonged residence times of river water would allow phytoplankton to bloom and take up nutrients, accumulating and increasing organic carbon biomass (Sun et al, 2021) and contributing more autochthonous and metabolism related POC and DOC (as biological leachate or as detritus). On the other hand, the prolonged residence times will make more suspended particles to settle onto the river floor, which then enhanced the water column transparence, increased the euphotic depth, and finally stimulated primary productivities (Zhang et al, 2010).…”

Section: Potential Factors Influencing Organic Matter Quantity and Qu...mentioning

confidence: 99%

Variations in dissolved and particulate organic carbon dynamics in the lower Changjiang River on time scales from seasonal to decades

Yue

Gao

Guo

2022

Preprint

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Abstract. Time series water samples were collected monthly between November 2016 and June 2019 from the Lower Changjiang (Yangtze) River at the Xuliujing station, representing the end-member freshwater exported to the ocean, in addition to monthly samples from November 2019 to January 2020 during an extreme drought event. Concentrations of dissolved (DOC) and particulate organic carbon (POC) as well as the stable isotopic composition of POC and PN (particulate nitrogen) were measured to elucidate their seasonal variations. Ultrafiltration was also conducted for selected samples to separate the bulk DOC into four different size-fractions to further examine changes in the molecular weight distribution of DOC. The seasonal variations of POC were characterized with higher proportions of autochthonous components in summer and lower proportions in winter on the basis of POC contents (% of total suspended particulate matter), δ13C, δ15N, and POC/PN values. The size spectra of DOC also illustrated a distinct seasonal variation pattern, although the different responses to different seasons were also shown between HMW- (high-molecular-weight) and LMW- (low-molecular-weight) DOC compounds. The strong correlation of δ13C values between HMW-DOC and POC suggested their close relationships in terms of origin and composition. Together with available literature data, DOC concentrations, POC (%), δ13C, and δ15N all showed a significant increase over the past decades, likely resulting from increase in the proportion of autochthonous organic components owing to intensified human activities and global warming in the river basin.

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“…The downstream-ward decreasing trend in the AT from Sichuan Basin to the downstream plain in dry season leads to a similar trend in the RWT through heat exchange (figure S2). However, during the post-TGR period, the replenished discharge in the dry season increases the water depth and shortens the water transport timescale downstream of the dam (Sun et al 2021), which weakens the cooling effect caused by the downstream-ward colder air and reduces the duration of the cooling process. As a result, the downstream-ward decreasing trend in the RWT is retarded, which leads to an additional increase in the downstream RWT in the dry season.…”

Section: Reduction In Seasonal Rwt Rangementioning

confidence: 99%

Roles of dam and climate change in thermal regime alteration of a large river

Xiao

Sun

Yuan

et al. 2022

Environ. Res. Lett.

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Water temperature in the Yangtze River mainstream has been experiencing significant changes due to the climate change and the operation of a series of world-class large dams, i.e., the Three Gorges Dam (TGD) and upstream cascade reservoirs (CDs). However, quantitative effects of these factors are not fully known, which hinders our understanding on the thermal regime alterations and further prediction in ecosystem response. Here, we will simulate the riverine water temperature (RWT) variations by building a physics-based model, and quantify the respective impacts from TGD, CDs and climate change through a model-based framework. In the framework, both the dam-regulated hydro-thermodynamic processes and the spatial heterogeneity of the meteorological condition in this large river-reservoir system are thoroughly considered. The results show a fluvial warming of 0.31~0.56 oC/10a in recent three decades, mainly attributed to climate change (44%~80% for different reaches). The dam has caused a substantial seasonal thermal lag in the dry season, e.g., ~40 days near the TGD, and accompanying severe alterations in the monthly RWT. A reduction of 10% in seasonal RWT is identified, which is attributed to both dam and climate change.

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Longitudinal transport timescales in a large dammed river - The Changjiang River

Cited by 13 publications

References 37 publications

Utilizing Satellite Imagery for Seasonal Trophic Analysis in the Freshwater Reservoir

Utilizing Satellite Imagery for Seasonal Trophic Analysis in the Freshwater Reservoir

Variations in dissolved and particulate organic carbon dynamics in the lower Changjiang River on time scales from seasonal to decades

Roles of dam and climate change in thermal regime alteration of a large river

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