Showing papers on "Siltation published in 2020"
TL;DR: It is estimated that ~53.0 Gt of terrestrial sediment has been retained on the mainland China because of human activities, with reservoir trapping, water resource utilization, and water-soil conservation measures accounting for 45.5%, 29%, and 25.5% of the total, respectively.
55 citations
TL;DR: The role of these kill mechanisms is likely to be depth-dependent with siltation and high temperatures potentially the most consequential in shallowest waters as mentioned in this paper, where weak dysoxia is seen in the extinction interval, recorded by the presence of pyrite framboids and glauconite and may have been a factor in the crisis even in coastal waters.
29 citations
TL;DR: In this paper, the authors used revised universal soil loss equation (RUSLE) and analytical hierarchy process (AHP) approach integrated with geospatial technology for modeling soil erosion hazard zone of West Kameng watershed of Arunachal Pradesh, Northeast India.
Abstract: Soil erosion has always been a major environmental problem in many parts of the world including the northeastern region of India. An increase in the rate of soil erosion has tremendous implications on land degradation, biodiversity loss, productivity, etc. Hence, assessment of soil erosion hazard and its spatial distribution is essential to serve as a baseline data for effective control measures. The present study uses revised universal soil loss equation (RUSLE) and analytical hierarchy process (AHP) approach integrated with geospatial technology for modeling soil erosion hazard zone of West Kameng watershed of Arunachal Pradesh, Northeast India. The assessment showed that the erodibility factor of soil ranged between 0 and 0.38 t/ha/MJ/mm and slope length and steepness factor increases with increase in slope angle. Lower normalized difference vegetation index (NDVI) values depict vegetation cover and higher values represent the rocky area or barren land. Spatial distribution of conservation support practice on soil loss indicated the variability (0–1) where lower value represents the higher conservation practice. The predicted average soil erosion rate was 124.21 t/ha/Yr. Normalized eigenvector values ranged between 0.03 and 0.20. The areas with more slope, relative relief, drainage density, lineament density, and frequency have shown comparatively higher eigenvector values, and it has been noticed that the strength of these eigenvectors reduces with a decrease in the values of the parameters. The spatial soil erosion potential map was delineated using eight geo-environmental variables (LULC, geomorphology, slope, relative relief, drainage density, drainage frequency, lineament density, and lineament frequency). The soil hazard map showed that the moderate soil erosion has the maximum (57.71%) area cover followed by high erosion class (26.09%) which depicts that most of the watershed areas are moderate to high vulnerable to soil erosion. The efficiency of the AHP was validated applying area under curve (AUC) method which result 84.90% accuracy in the present study. Based on the findings, it is being recommended that present watershed requires adequate control procedures on a priority basis to conserve soil resources and reduce flood events and siltation of water bodies.
27 citations
TL;DR: In this paper, a Delft 3D module by observing hydrodynamic and sediment data to simulate the hydrodynamics and seabed erosion during a storm event in the littoral area of YRD is presented.
20 citations
TL;DR: In this paper, the behavior of suspended sediment transported in suspension in the Lower Mekong River (LMR) along approximately 1700 km from fluvial to estuarine environments was assessed, simultaneously with hydrodynamic conditions.
Abstract: The Mekong river is one of the largest rivers in the world, which flows through six countries of Southeast Asia (China, Myanmar, Laos, Thailand, Cambodia and Vietnam). Its hydro-sedimentary regime is changing rapidly, as a consequence of a regional shift of land use (agriculture, road, etc.), damming, sand mining and climate changes, among others. This study assesses the behavior of particles transported in suspension in the Lower Mekong River (LMR), along approximately 1700 km from fluvial to estuarine environments. Suspended sediment properties were estimated, simultaneously with hydrodynamic conditions, during three field campaigns. In addition, further investigations were performed in the laboratory to assess the structures of particles (flocculated or not), their capacity to flocculate (and the impacts on siltation), under a wide range of sediment concentration (20–30,000 mg.L−1). This study confirms that suspended sediment transported in the LMR are predominantly (75% by volume) flocculi (or freshly eroded soils aggregates), with median aggregated particle size in the range 10–20 μm and median settling velocity of the order of 0.01–0.1 mm s−1. These flocculi are robust under the hydrodynamic conditions (turbulence and suspended sediment concentration – SSC) existing in the LMR. Laboratory investigations reveal the existence of a threshold sediment concentration (400 mg.L−1), beyond which flocculation and sedimentation increase of orders of magnitudes. Thus, concentration that exceeds this threshold might promote the formation of so-called fluid mud layers. Because of the nonlinear response of flocculation and sedimentation with SSC and considering the ongoing changes at a regional scale in the LMR, higher occurrence of fluid mud layers in the fluvial upstream waterbodies might be anticipated, and a lower occurrence in estuaries and alongshore where the concentration decrease. The geomorphology could be impacted, with an over-siltation in dams and an exacerbated erosion of the muddy-mangrove coast.
19 citations
TL;DR: It was observed that the negative effects of the dramatic increases in mineral suspension loads were synergistically aggravated by the presence of objects disturbing fluvial system continuity and the consequences of the synergy between these two factors were evident in local brown trout populations.
17 citations
TL;DR: In this article, the authors used a hydrological model (HEC-HMS) coupled with a sediment transport model to simulate future changes in river discharge and sediment load to calculate the siltation of the Capillucas storage reservoir.
17 citations
TL;DR: Wang et al. as mentioned in this paper applied 3S technology, landscape ecology, and computational models to investigate the impact of the Three Gorges Dam on downstream spatial dynamics of floodplains in future.
Abstract: The operation of the Three Gorges Dam (TGD) has significantly impact on downstream wetland ecosystems. This study applied 3S technology, landscape ecology, and computational models to investigate impact of the TGD on downstream spatial dynamics of floodplains in future. Results revealed the relationship between siltation patterns and wetland types transformation after the operation of the TGD, which are critically important to understand ecological characters dynamics in new environmental setting, and provide science-based conservation and restoration recommendation. After the operation of the TGD, changes between water surface and floodplains areas were spatial heterogeneity. With the increase of distance to the TGD, floodplain erosion force declining gradually. The most important finding is the asymmetric erosion between main river course and its associated floodplain lakes, e.g., Dongting lake.This has significant implications for dam operation in autumn and habitat management. After the operation of the TGD, floodplain in the estuary is driven by both the Yangtze river and ocean currents. The strong hydrological force and reduced sediments of Yangtze river drive erosion of the southern river course in the estuary, whereas, the weakened hydrological force in the northern river course attracts sedimentation.
15 citations
TL;DR: It is concluded that the supposed rise of precipitation in Central Europe due to climate change will lead to an increase in the levels of stored sediment in reservoirs, and it is recommended for reservoir managers to use USPED model and to include the estimation of modelling of siltation rate into reservoirs' maintenance projects.
15 citations
TL;DR: Wang et al. as discussed by the authors investigated the annual to decadal morphological changes in the North Branch of the Yangtze Delta by using time-series satellite images from 1984 to 2018, and controlling factors and mechanism were analyzed in the context of complex human-earth interactions.
13 citations
TL;DR: The use of ASTER data is demonstrated to map the siltation of the Al-Khod Dam constructed at the lower reaches of Samail Catchment area, north Muscat, Sultanate of Oman with results verified in the field and confirmed through laboratory analyses.
Abstract: This study demonstrates the use of ASTER data to map the siltation of the Al-Khod Dam constructed at the lower reaches of Samail Catchment area, north Muscat, Sultanate of Oman In this study, the decorrelated image of spectral bands 6, 3, and 1 clearly discriminated the distribution of siltation The occurrence of siltation is confirmed by the detection of minerals using the VNIR-SWIR bands by the Spectral Angle Mapper (SAM) method In addition, the siltation of the dam is studied for the years 1987 to 2018 using Landsat satellite images Interpretation of images showed a gradual increase of the siltation Mapping accuracy for the occurrence of siltation is assessed by a confusion matrix which produced an overall accuracy of 9788% and Kappa coefficient of 098 in the Maximum Likelihood method Results of image analyses are verified in the field and confirmed through laboratory analyses The study of spectral absorption characters of field samples using a Portable Infrared Mineral Analyzer (PIMA) showed the presence of OH molecule bearing minerals (clays, serpentines, etc) and carbonate minerals (calcite and dolomite) in the silt deposits The occurrence of these minerals is confirmed further by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analyses
TL;DR: In this paper, the authors review existing approaches for mapping erosional hotspots, and provide an example of spatial-temporal mapping approach in two case study regions, and discuss the barriers limiting data availability and their effects on erosion mapping methods, their validation, and resulting prioritization of leverage management areas.
Abstract: Land degradation and water availability in semi-arid regions are interdependent challenges for management that are influenced by climatic and anthropogenic changes. Erosion and high sediment loads in rivers cause reservoir siltation and decrease storage capacity, which pose risk on water security for citizens, agriculture, and industry. In regions where resources for management are limited, identifying spatial-temporal variability of sediment sources is crucial to decrease siltation. Despite widespread availability of rigorous methods, approaches simplifying spatial and temporal variability of erosion are often inappropriately applied to very data sparse semi-arid regions. In this work, we review existing approaches for mapping erosional hotspots, and provide an example of spatial-temporal mapping approach in two case study regions. The barriers limiting data availability and their effects on erosion mapping methods, their validation, and resulting prioritization of leverage management areas are discussed.
TL;DR: The increase of freshwater inflow to Kalametiya lagoon, Sri Lanka, as a result of Udawalawe irrigation project that came into operation in 1967, has caused heavy siltation and reduction of salinity as mentioned in this paper.
Abstract: The increase of freshwater inflow to Kalametiya lagoon, Sri Lanka, as a result of Udawalawe irrigation project that came into operation in 1967, has caused heavy siltation and reduction of salinity...
TL;DR: In this article, high resolution in-situ flux measurements were collected at stations 1.5 and 6.5 km seaward of the Geum estuarine dam, Korea.
Abstract: While estuarine dams have been noted for often resulting in siltation, the flux mechanism and the effect of the dam on the fluxes is not well understood. To gain process-based insight into the spatiotemporal variation and factors that control sediment flux, high resolution in-situ flux measurements were collected at stations 1.5 km and 6.5 km seaward of the Geum estuarine dam, Korea. Fluxes were calculated based on flow collected by Acoustic Doppler Current Profilers (ADCPs) and suspended sediment concentration derived from ADCP acoustic backscatter which was calibrated with water samples. The fluxes were decomposed into components occurring on timescales longer than the tidal cycle (mean-flow flux) and those occurring on the tidal timescale (correlation flux), and ship-borne surveys were conducted to investigate the role of the dam-induced horizontal salinity gradient to stratification and sediment dynamics. Results suggest that the landward correlation fluxes increased because the dam construction amplified the tide and because the correlation flux was proportional to the tidal amplitude, through tidal asymmetry. The dam discharge was found to control the seaward mean-flow fluxes, which were characteristically unsteady and proportional to the discharged volume. Discharge also was found to result in periodic stratification and flocculation asymmetry. The bed level change between the two stations was a balance between the effects of tidal asymmetry and freshwater discharge. For shallow, macrotidal estuaries with small discharge, estuary siltation is expected primarily due to correlation fluxes, and the effect is enhanced when the dam installation amplifies the tides.
TL;DR: Using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, the authors quantified the sediment retention capacity and water yield potential of different land cover in the Santee River Basin Network in South Carolina, USA.
Abstract: The increasing pressure from land cover change exacerbates the negative effect on ecosystems and ecosystem services (ES). One approach to inform holistic and sustainable management is to quantify the ES provided by the landscape. Using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, this study quantified the sediment retention capacity and water yield potential of different land cover in the Santee River Basin Network in South Carolina, USA. Results showed that vegetated areas provided the highest sediment retention capacity and lowest water yield potential. Also, the simulations demonstrated that keeping the offseason crop areas vegetated by planting cover crops improves the monthly ES provision of the landscape. Retaining the soil within the land area prevents possible contamination and siltation of rivers and streams. On the other hand, low water yield potential translates to low occurrence of surface runoff, which indicates better soil erosion control, regulated soil nutrient absorption and gradual infiltration. The results of this study can be used for landscape sustainability management to assess the possible tradeoffs between ecological conservation and economic development. Furthermore, the generated map of ES can be used to pinpoint the areas where ES are best provided within the landscape.
TL;DR: In this article, the authors quantify the extent of channel migration, erosion-accretion, river width, sinuosity, and charland morpho-dynamics from 1972 to 2018 using geospatial techniques combined with satellite images and hydrological data.
Abstract: Bangladesh is a riparian country that is criss-crossed by the many tributaries and distributaries of the mighty Ganges, Brahmaputra, and Meghna river systems. Gorai-Madhumati, a distributary of the Ganges River is an example where morphological development of the river is associated with frequent channel shifting within the catchment area. The main objective of this research is to quantify the extent of channel migration, erosion-accretion, river width, sinuosity, and charland morpho-dynamics from 1972 to 2018 using geospatial techniques combined with satellite images and hydrological data. The study also addressed the impacts of Farakka Barrage construction in India on the shifting, flow behavior, and siltation of Gorai-Madhumati River. The study shows that bar surface areas have abnormally increased in both segments after 1975 due to the construction of Farakka Barrage. Water flow in the Gorai-Madhumati has dropped remarkably in the downstream and instigated huge sedimentation in this region. Analysis of the time series satellite images revealed that the morphology of the river channel experienced huge changes simultaneously with the changes in the seasonal flow and sedimentation all over the study period. Migration trend has frequently shifted and taken place in the NW and NE direction in the observed sections of the river. Throughout the study period, total amount of accretion was greater than the net percentage of erosion on both banks of the river. River discharge, bar accretion, and erosion history show that the Gorai-Madhumati River will no longer exist with the present flowing condition without attention and proper river management.
TL;DR: In this article, the authors studied the hydrodynamic water circulation in the lake and the transport of the Total Suspend Matter (TSM) in order to study the hydromorphology and ecology of the lake.
TL;DR: In this article, a three-dimensional hydro-sedimentary model (TELEMAC-3D) was calibrated with field measurements from 2014 to 2019, and in situ measurements (turbidity, bathymetric surveys, seabed elevation) showed that the macro-tidal influence and local wind-wave regime significantly contributed to siltation in the marina.
TL;DR: In this article, a TELEMAC-2D numerical modeling was performed to elucidate the characteristics and mechanism of siltation in the two seagoing waterways under usual and extreme flood conditions.
TL;DR: In this paper, the authors used the Soil and Water Assessment Tool (SWAT) to estimate the sedimentation yields in the Kaligandaki basin of Nepal, which is an important tributary that drains into the Ganges.
Abstract: Himalayan regions have increasing sediment yield due to undulating topography, slope and improper watershed management. However, due to limited observation data, and site accessibility issues, less studies have quantified sedimentation loads in the Himalayas, especially Nepal. This has hindered the investments on run-of-river hydropower projects as high and unpredicted sedimentation has increased losses in hydropower production. Therefore, there is a need to understand key physical processes driving sedimentation in these regions, with the available data. This study used the Soil and Water Assessment Tool (SWAT) to estimate the sedimentation yields in the Kaligandaki basin of Nepal, which is an important tributary that drains into the Ganges. Multi-source data from field observations, remote sensing platforms, surveys and government records were used to set up and run the SWAT model for the Kaligandaki basin from 2000 to 2009. Results for the 10-year model run indicate that 73% of the total sediment load is estimated to come from the upstream regions (also known as High Himalayan region), while only 27% is contributed from the Middle and High Mountain regions (where land management-based interventions were deemed most feasible for future scenarios). The average sediment concentration was 1986 mg/kg (ppm), with values of 8432 and 12 mg/kg (ppm) for maximum and minimum, respectively. Such high sedimentation rates can impact river ecosystems (due to siltation), ecosystem services and hydropower generation. In addition, model results indicate the need for better high frequency observation data. Results from this study can aid in better watershed management, which is aimed at reducing sedimentation load and protecting Himalayan rivers.
01 Nov 2020
TL;DR: In this article, the authors used the SWAT hydro-agricultural model and the integrated RUSLE model to assess soil losses and characterize the degraded areas of the M'dez watershed, located in the upper Sebou, north of the Middle Atlas, and extend on an area of 3350 km2.
Abstract: The preservation of soil resources is a primary global concern and a permanent challenge for all Mediterranean countries. In Morocco, the capacity of dam reservoirs continues to decline from one year to the next due to the rate of siltation, mainly due to the phenomenon of water erosion. Indeed, the origins of this erosion are generally related to land use planning, deforestation, agricultural practices and low vegetation cover. However, it is imperative to quantify soil erosion and its spatial distribution to achieve sustainable land use and governance of this resource. The SWAT hydro-agricultural model and the integrated RUSLE model were used to assess soil losses and characterize the degraded areas of the M’dez watershed, located in the upper Sebou, north of the Middle Atlas, and extend on an area of 3350 km2. The results obtained during this work show that the average soil losses estimated by the two models are consistent. For the SWAT model, the specific degradation of the watershed is estimated at 3.95 t/ha/year, whereas for the RUSLE model, the average loss of the basin is estimated at 2.94 t/ha/year). However, the use of these two models (SWAT and RUSLE), for the assessment and characterization of degraded areas at the level of Moroccan watersheds, has become a much sought-after approach for good soil conservation management.
Abstract: Erosion and solid transport is a tricky and complex problem that negatively affects natural and urban environments. In Algeria, the effects of this phenomenon are apparent; their impact is no less devastating in the long term than the other spectacular catastrophic phenomena that can be observed. Sixty-five large dams in Algeria are threatened by the reduction of 62% of their storage capacity because of the siltation problem (ANBT) (National Agency for Dams and Water Transfers). The main objective of this work is the evaluation of the impact of the erosion phenomenon on Bechar watershed which is in an area characterized by an arid climate. The universal soil loss equation was used. This model is based on the combination of the five factors (erosivity, erodibility, topography, vegetation cover and support practices) that directly influence this phenomenon. Analytical hierarchy process is used to give a weighting value of each factor according to its degree of influence on the phenomenon. The sediment delivery ratio is calculated to determine the amount of soil that will arrive at the outlet of the watershed and contribute to the storage structures siltation. The obtained results will undoubtedly help decision makers to understand the threat of erosion degree in the study area in order to better take the necessary measures to face this issue.
TL;DR: In this article, a comparison of geo-referred bathymetric datasets from 2000 to 2017, at different timescales, allowed to analyze changes in the sedimentary balance and to determine patterns of morphological adjustment in the Magdalena River (South America).
Abstract: s Comparison of geo-referred bathymetric datasets from 2000 to 2017, at different timescales, allowed to analyze changes in the sedimentary balance and to determine patterns of morphological adjustment in the Magdalena River (South America). The Magdalena River has one of the highest sediment yields among the major rivers of the world. In addition, it is a laterally constrained river mouth due to a series of man-made structures inhibiting its morphological response. Thus, it provides an illustrative example to study siltation processes in a river mouth system where a low capacity of morphological response interacts with a high-magnitude sediment transport regime. The river mouth exhibited an overall slow-pace deepening trend between 2000 and 2017. However, it experienced cyclic shifts between erosive and siltation states, both at interannual and intra-annual scales. The rates of erosion were 310 mm yr−1 on average during the erosional stages. Whereas sedimentation rates were 293 mm yr−1 on average during the sedimentation stages. Maximum rates of erosion and sedimentation were 1450 mm yr−1 and 2625 mm yr−1, respectively. However, intra-annual rates of sedimentation/erosion were of the same magnitude or larger compared with the interannual rates. Such high rates and the rapid changes in the sedimentary balance is the result of the cumulative effect of its limited morphological response capacity and its large suspended sediment load. These rapid processes generate constraints and threats to navigation. Particularly, at intra-annual scales. Consequently, innovative intervention proposals, recognizing the rapid transitions and geomorphological adaptations, are required for managing this type of river mouths.
TL;DR: In this article, an extensive inventory of barriers in the Douro river basin was carried out for the present study, which allowed a prognosis on the watershed siltation risk.
Abstract: Forest fires are an increasing problem over recent decades. The fires, among other consequences, lead to an increase in the soil vulnerability to water erosion and a consequent increase in sedimentation rates. When barriers are present, such as dams or weirs, there is an amplified risk of sediment and ash deposition in their reservoirs, causing siltation. Thus, there is an interest in studying in more detail the risk of siltation of barriers and reservoirs in the Douro River watershed following wildfires. A detailed barrier inventory was lacking for the Douro River, hampering the identification of siltation-prone areas. In order to fill in this gap, an extensive inventory of barriers in the Douro river basin was carried out for the present study. The result was an abundant and reliable dataset on the Douro River barriers, which allowed a prognosis on the watershed siltation risk. The method for calculating the siltation risk relied on the relationship between the frequency of forest fires, the erosion risk and the frequency of reservoirs. The sub-basins with the greater siltation risk are the Tâmega, Corgo, Sousa and Paiva river basins. Most reservoirs with the highest siltation risk were from small dams. The modelling results were compared with stream connectivity and concentrations of stream water phosphorus (associated with the sediments that flow into the rivers due to the fires). With regard to connectivity, only two reservoirs were at high risk of sedimentation due to fires, so the categories of connectivity risk and fire-based sedimentation risk are probably not related. With regard to risk of high phosphorus loadings, in 8 basins the upper classes for fire-based erosion risk coincided with the upper class for phosphorus loadings suggesting that high phosphorus loading could be associated with fire-based erosion. This study works as a simple but reliable example on the assessment and mapping of siltation risk in stream networks intersected by abundant barriers. It allowed for identifying barriers that can accumulate a large quantity of fine sediments and ashes, interfering with water quality and soil erosion as well as with the storage capacity of the respective barriers.
TL;DR: In this paper, a qualitative and quantitative analysis of suspended sediment and its origin in a small reservoir located in Blizne, Podkarpackie Region (SE Poland), and was conducted during summer 2017.
Abstract: The study involved qualitative and quantitative analysis of suspended sediment and its origin in a small reservoir located in Blizne, Podkarpackie Region (SE Poland), and was conducted during summer 2017. Results showed a linear negative correlation between the suspended sediment in a water column and its organic matter content. There was also a clear relationship between the suspended sediment content and the rate of sedimentation of solid particles suspended in the water column. The research showed that the TOC-to-OM conversion factor commonly applied to bottom sediments does not apply to sediments suspended in the water column. It was also observed that the organic matter prevailing in entrapped sediment was of autochthonous origin. Its share was greatest and the content of total phosphorus highest when retention period increased. The increase in phosphorus content co-occurred with the decreasing TOC:TN ratio, and with a decrease in the sedimentation rate. Analysis has thus shown that the composition and specific nature of suspended sediment in this reservoir affects the rate of deposition of matter and can determine the siltation processes.
TL;DR: A high relation of sediment yield with maximum water flow of the event (Qmax), and linear regression models showed the best performance between characteristic variables.
Abstract: Sediment yield in river catchments can cause siltation of reservoirs and channels, carries contaminants adhered to sediment particles, and represents water erosion at the catchment scale, leading to decreased agricultural productivity. Hydrological monitoring enables the understanding of overland flow and soil erosion dynamics. In this study, we analyzed whether the relationship between precipitation (P), water flow (Q), and suspended sediment concentration (SSC) during rainfall events shows the usefulness of hydrological and sedimentological monitoring in soil and water conservation projects to river catchments. We conducted a study in the Lajeado Ferreira catchment in southern Brazil. This catchment is characterized by high soil fragility and erosion rates because of relief and intense tobacco cultivation. The small size of the catchment (120 ha) allowed a better understanding of the processes that occurred between hillslope and watercourses. We analyzed 43 rainfall-runoff events (P-Q), and we selected characteristic variables of each event and related them to independent variables (climate, land use, and soil management) and their seasonality using regression techniques. We also conducted a hysteresis analysis to understand the behavior of SSC in relation to runoff. The results showed a high relation of sediment yield (SY) with maximum water flow of the event (Qmax), and linear regression models showed the best performance between characteristic variables. In addition, the seasonal variability of the land coverage presented greater influence on the SY than the precipitation itself.
TL;DR: In this article, the influence of snowmelt and rainfall on soil erosion processes and siltation of small lakes in Miyagi Prefecture (150 km northwest of the power plant) was examined.
TL;DR: In this article, the effect of riverbed siltation on the hydrochemistry and redox reactions of infiltrated water was studied. But, the results of this study were limited due to the high variability in these processes.
Abstract: The upper part of riverbed sediment is one of the key interfaces between surface water and groundwater, and biogeochemical process in this interface has a profound influence on the chemistry of infiltrated water. The lithology and permeability of bed sediment is mainly controlled by variation in river hydrodynamic conditions. However, there have been few studies of the effect of riverbed siltation on the hydrochemistry and redox reactions of infiltrated water due to the high variability in these processes and challenges associated with sampling. This study selected and examined a river channel near a site of riverbank filtration by drilling on the floating platform and conducting microelectrode testing and high-resolution sampling. The hydrodynamic and chemical characteristics of pore water in and lithologic characteristics of riverbed sediment, the siltation, and redox zone were examined and compared. Differences in hydrodynamic conditions changed the lithology of riverbed sediment, consequently affecting redox reactions during the process of river water infiltration. Variations in siltation changed the residence time of pore water and organic matter content, which ultimately resulted in differences in extension range and intensity of redox reactions. This study provides a valuable reference for understanding the effect of riverbed siltation on water quality of riverbank infiltration.
05 Feb 2020
TL;DR: In this article, the effect of siltation undermines reservoir sustainability because it undermines reservoirs' sustainability, and the authors propose a solution to solve this problem. But, the solution is limited to a single reservoir.
Abstract: Reservoirs are installed as long-term assets to guarantee water and energy security for decades, if not centuries. However, the effect of siltation undermines reservoirs’ sustainability because it ...
TL;DR: In this paper, field observations of the Deep Water Navigational Channel (DNC) in the North Passage of the Changjiang Estuary were conducted by 16 anchored boats in the navigation channel of North Passage during spring tide in the flood season.
Abstract: After the construction of the Deep-water Navigational Channel (DNC) in the North Passage of the Changjiang Estuary, siltation in the channel became severe during the flood season in the navigation channel. To investigate the causes, field observations of tidal current, salinity and suspended sediment concentration (SSC) were conducted by 16 anchored boats in the navigation channel of North Passage during spring tide in the flood season. The across-channel differences of salinity, SSC, and near bottom residual sediment transport at the high siltation area of the DNC were observed and analyzed. The results show that the near bottom SSC presented a south-to-north decreasing trend during the flood tide at the lower reach of the North Passage. During the ebb tide, a suspended sediment cloud of extremely high concentration was detected within the channel. The observed longitudinal sediment trapping was not only shown as the turbidity maximum (TM) trapped within the moving salinity front but also as the longitudinal convergence of the residual sediment transport at the middle reach. The mechanism for the longitudinal sediment trapping was due to the tidal asymmetry in mixing. The observed lateral sediment trapping was prominent at the most severe siltation area of the DNC in the section #2. The lateral sediment trapping at the across-channel section #2 was not only shown as the lateral transport of the sediments from the channel flanks during the flood slack but also as the lateral convergence of the residual sediment transport during the entire spring tidal cycle. The mechanism for the lateral sediment trapping was dominated by the advective transport. The lateral impact on the channel sediment trapping was not negligible in view of the depth-mean lateral tidal straining on the water stratification. The observed convergences of both the longitudinal and the lateral residual sediment transports were responsible for the severe channel siltation in the North Passage.