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Assessment of Daily Streamflow, Sediment Fluxes, and Erosion Rate of a Pro-glacial Stream Basin, Central Himalaya, Uttarakhand
Reliable information of hydrological processes within a river basin is essentially required for developing an appropriate strategy for achieving sustainable development goals. The present study assesses the streamflow of a pro-glacial stream and also intends to estimate the contribution of suspended sediments, erosion rate, and the headwater contribution of the Panchachuli glacier. A field study during ablation period was carried out to measure streamflow and suspended sediment concentration (SSC). Further, HBV model was used to estimate the snowmelt. The average seasonal streamflow and SSC during the gauging period (July to October) for the basin were measured to be 7.17 m3/s, and 1.52 g/l in 2018, and 6.84 m3/s, and 1.21 g/l in 2019, respectively. Snowmelt contribution in total streamflow was 54.75% in 2018 which is reduced to 49.16% in 2019. Similarly, glacier melt contributes to 32.62% of its total runoff share in 2018 which was reduced to 28.73% in 2019. The rainfall runoff in total runoff increased to 12.62% from 2018 to 2019. Rainfall-runoff in its total runoff contribution showed an increased share of 22.13% in 2019. The streamflow, SSC, and suspended sediment load (SSL) showed a strong positive correlation for both the years. The suspended sediment yield (SSY), SSL, and erosion rate of the basin were found as high as compared to the other Himalayan basins in Himachal Pradesh, Jammu and Kashmir, and Ladakh and non-Himalayan regions that was found low when compared to other glaciers in Uttarakhand.
Journal Article
Watershed Suspended Sediment Supply and Potential Impacts of Dam Removals for an Estuary
Observations and modeling are used to assess potential impacts of sediment releases due to dam removals on the Hudson River estuary. Watershed sediment loads are calculated based on sediment-discharge rating curves for gauges covering 80% of the watershed area. The annual average sediment load to the estuary is 1.2 Mt, of which about 0.6 Mt comes from side tributaries. Sediment yield varies inversely with watershed area, with regional trends that are consistent with substrate erodibility. Geophysical and sedimentological surveys in seven subwatersheds of the Lower Hudson were conducted to estimate the mass and composition of sediment trapped behind dams. Impoundments were classified as (1) active sediment traps, (2) run-of-river sites not actively trapping sediment, and (3) dammed natural lakes and spring-fed ponds. Based on this categorization and impoundment attributes from a dam inventory database, the total mass of impounded sediment in the Lower Hudson watershed is estimated as 4.9 ± 1.9 Mt. This represents about 4 years of annual watershed supply, which is small compared with some individual dam removals and is not practically available given current dam removal rates. More than half of dams impound drainage areas less than 1 km², and play little role in downstream sediment supply. In modeling of a simulated dam removal, suspended sediment in the estuary increases modestly near the source during discharge events, but otherwise effects on suspended sediment are minimal. Fine-grained sediment deposits broadly along the estuary and coarser sediment deposits near the source, with transport distance inversely related to settling velocity.
Journal Article
Estuarine and coastal hydrography and sediment transport
\"A practical guide to the latest remote and in situ techniques used to measure sediments, quantify seabed characteristics, and understand physical properties of water and sediments and transport mechanisms in estuaries and coastal waters. Covering a broad range of topics from global reference frames and bathymetric surveying methods to the use of remote sensing for determining surface-water variables, enough background is included to explain how each technology functions. The advantages and disadvantages of each technology are explained, and a review of recent fieldwork experiments demonstrates how modern methods apply in real-life estuarine and coastal campaigns. Clear explanations of physical processes show links between different disciplines, making the book ideal for students and researchers in the environmental sciences, marine biology, chemistry and geology, whose work relies on an understanding of the physical environment and the way it is changing as a result of climate change, engineering and other influences\"-- Provided by publisher.
Book
Evaluating tracer selection for catchment sediment fingerprinting
PurposeRecent sediment fingerprinting research has shown the sensitivity of source apportionment results to data treatments, tracer number, and mixing model type. In light of these developments, there is a need to revisit procedures associated with tracer selection in sediment fingerprinting studies. Here, we evaluate the accuracy and precision of different procedures to select tracers for un-mixing sediment sources.Materials and methodsWe present a new approach to tracer selection based on identifying and removing tracers that exhibit non-conservative behaviour during sediment transport. This removes tracers on the basis of non-conservative behaviour identified using (1) tracer-particle size relationships and (2) source mixing polygons. We test source apportionment results using six sets of tracers with three different synthetic mixtures comprising one, five, and ten mixture samples. Source tracer data was obtained from an agricultural catchment in northwest England where time-integrated suspended sediment samples were also collected over a 12-month period. Source un-mixing used MixSIAR, a Bayesian mixing model developed for ecological food web studies, which is increasingly being applied in catchment sediment fingerprinting research.Results and discussionWe found that the most accurate source apportionment results were achieved by the selection procedure that only removed tracers on the basis of non-conservative behaviour. Furthermore, accuracy and precision were improved with five or ten mixture samples compared to the use of a single mixture sample. Combining this approach with a further step to exclude additional tracers based on source group non-normality reduced accuracy, which supports relaxation of the assumption of source normality in MixSIAR. Source apportionment based on the widely used Kruskal-Wallis H test and discriminant function analysis approach was less accurate and had larger uncertainty that the procedure focused on excluding non-conservative tracers.ConclusionsSource apportionment results are sensitive to tracer selection. Our findings show that prioritising tracer exclusion due to non-conservative behaviour produces more accurate results than selection based on the minimum number of tracers that maximise source discrimination. Future sediment fingerprinting studies should aim to maximise the number of tracers used in source un-mixing constrained only by the need to ensure conservative behaviour. Our procedure provides a quantitative approach for identifying and excluding those non-conservative tracers.
Journal Article
Equilibrium sediment exchange in the earth’s critical zone: evidence from sediment fingerprinting with stable isotopes and watershed modeling
PurposeThe equilibrium sediment exchange process is defined as instantaneous deposition of suspended sediment to the streambed countered by equal erosion of sediment from the streambed. Equilibrium exchange has rarely been included in sediment transport studies but is needed when the sediment continuum is used to investigate the earth’s critical zone.Materials and methodsNumerical modeling in the watershed uplands and stream corridor simulates sediment yield and sediment source partitioning for the Upper South Elkhorn watershed in Kentucky, USA. We simulate equilibrium exchange when upland-derived sediment simultaneously deposits to the streambed while streambed sediments erode. Sediment fingerprinting with stable carbon isotopes allowed constraint of the process in a gently rolling watershed.Results and discussionCarbon isotopes work well to partition upland sediment versus streambed sediment because sediment deposited in the streambed accrues a unique autotrophic, i.e., algal, fingerprint. Stable nitrogen isotopes do not work well to partition the sources in this study because the nitrogen isotope fingerprint of algae falls in the middle of the nitrogen isotope fingerprint of upland sediment. The source of sediment depends on flow intensity for the gently rolling watershed. Streambed sediments dominate the fluvial load for low and moderate events, while upland sediments become increasingly important during high flows and extreme events. We used sediment fingerprinting results to calibrate the equilibrium sediment exchange rate in the watershed sediment transport model.ConclusionsOur sediment fingerprinting and modeling evidence suggest equilibrium sediment exchange is a substantial process occurring in the system studied. The process does not change the sediment load or streambed sediment storage but does impact the quality of sediment residing in the streambed. Therefore, we suggest equilibrium sediment exchange should be considered when the sediment continuum is used to investigate the critical zone. We conclude the paper by outlining future research priorities for coupling sediment fingerprinting with watershed modeling.
Journal Article
Sedimentary crisis at the global scale
Volume 1: \"The Earth's oceans are currently undergoing unprecedented changes: rivers have suffered a severe reduction in their sediment transport, and as a result, sediment input to the oceans has dropped lower than ever before. These inputs have varied over millennia as a result of both natural occurrences and human actions, such as the building of dams and the extraction of materials from riverbeds. Sedimentary Crisis at the Global Scale 1 examines how river basins have been affected by the sedimentary crises of various historical epochs. By studying global balances, it provides insights into the profound disruption of the solid transport of fluvial bodies. The book also explores studies of various rivers, from the Amazon, which remains relatively unaffected, to dying rivers such as the Colorado and the Nile.\" -- Back cover.
Book
Monitoring Discharge and Suspended Sediments in the Yangtze River Tidal Reach Using Coastal Acoustic Tomography
Conventional methods of measuring water discharge and suspended sediment concentration (e.g., water sampling and moving acoustic Doppler current profiler [ADCP]) present challenges in large tidal rivers due to temporal and spatial constraints. This study introduces a novel approach to monitor water discharge and suspended sediment discharge (SSD) in large tidal rivers. Total water discharge and SSD exhibit notable variability in tidal rivers due to the river–tidal interactions; understanding this variability and its causes is essential for effective tidal river management. From June to November 2023, a field study was conducted at Nanjing (NJ) to continuously monitor water discharge, suspended sediment concentration (SSC), and SSD in the tidal reaches of the Yangtze River using coastal acoustic tomography (CAT). Total water discharge ranged from 8,765 to 43,356 m3/s, with a mean of 27,825 m3/s, while tidal discharge varied between −11,998 and 9,983 m3/s, with a mean of 69 m3/s. SSC ranged from 0.02 to 0.09 kg/m3, and SSD ranged from 110 to 3,823 kg/s. Tidal variations in SSC and SSD were within ±0.04 kg/m3 and −1,252 to 1,410 kg/s, respectively. Over short timescales, tides caused instantaneous fluctuations in velocity, water discharge, and SSD, with tides contributing −40% to instantaneous water discharge and SSD at NJ. Over seasonal timescales, no significant wet/dry variations were observed in water discharge, SSC, or SSD during a few months of 2023. Long‐term CAT application (e.g., decades) is required to reveal trends in tidal river dynamics. Plain Language Summary Due to temporal and spatial limitations, traditional methods for measuring suspended sediment concentration (SSC) and discharge, such as moving acoustic Doppler current profilers (ADCP), fail to directly measure transect variations in water discharge, SSC, and SSD in tidal reaches of the Yangtze River. This study developed a new method using coastal acoustic tomography (CAT). Two CAT systems were utilized to continuously measure water discharge, SSC, and SSD at the Nanjing Tidal Station. The CAT results were highly consistent with traditional methods, showing a correlation coefficient greater than 0.9. This study demonstrates the potential of CAT for continuous, real‐time monitoring of water discharge, SSC, and SSD in large tidal rivers. The results showed that mean water discharge, SSC, and SSD are primarily driven by river flow at Nanjing, while tides induce instantaneous variations in water discharge and sediment transport. Key Points Coastal acoustic tomography enabled water discharge and suspended sediment discharge (SSD) monitoring in Nanjing tidal reach of Yangtze River Total water discharge and SSD at Nanjing varied from 8,765 to 43,356 m3/s and 110–3,823 kg/s from June to November 2023, respectively Tides can directly trigger instantaneous variations in sediment discharge, while average sediment discharge is river‐dominated at Nanjing
Journal Article