Sedimentation Rates Research Articles

Organic carbon accumulation in British saltmarshes

Saltmarshes are a crucial component of the coastal carbon (C) system and provide a natural climate regulation service through the accumulation and long-term storage of organic carbon (OC) in their soils. These coastal ecosystems are under growing pressure from a changing climate and increasing anthropogenic disturbance. To manage and protect these ecosystems for C and to allow their inclusion in emissions and natural-capital accounting, as well as carbon markets, accurate and reliable estimates of OC accumulation are required. However, globally, such data are rare or of varying quality. Here, we quantify sedimentation rates and OC densities for 21 saltmarshes in Great Britain (GB). We estimate that, on average, saltmarshes accumulate OC at a rate of 110.88 ± 43.12 g C m−2 yr−1. This is considerably less than widely applied global saltmarsh averages. It is therefore highly likely that the contribution of northern European saltmarshes to global saltmarsh OC accumulation has been significantly overestimated. Taking account of the climatic, geomorphological, oceanographic, and ecological characteristics of all GB saltmarshes and the areal extent of different saltmarsh zones, we estimate that the 451.65 km2 of GB saltmarsh accumulates 46,563 ± 4353 t of OC annually. These low OC accumulation rates underline the importance of the 5.20 ± 0.65 million tonnes of OC already stored in these vulnerable coastal ecosystems. Going forward the protection and preservation of the existing stores of OC in GB saltmarshes must be a priority for the UK as this will provide climate benefits through avoided emissions several times more significant than the annual accumulation of OC in these ecosystems.

Effects of occupational exposure on the hematologic parameters among welders

Introduction: The effect of prolonged exposure to welding fumes on blood levels remains an unresolved question. In our study, we aimed to determine the effects of metal fume exposure on various blood parameters in welders. Materials and Methods: The study was cross-sectional. It included all male welding workers admitted to a health institution, a reference hospital for occupational diseases, for 2021. It was conducted with 254 individuals. The variables examined included age, duration of employment, smoking habit, body mass index, hemoglobin levels, erythrocyte, leukocyte and platelet counts, aspartate aminotransferase, alanine aminotransferase, free prostate-specific antigen, creatinine and manganese levels, and erythrocyte sedimentation rates. Results: In our study, 40.6% of the welders were between 21-30 years old. 65.7% of the participants have been welding for more than five years. According to body-mass index values, 44.1% of the participants were pre-obese, and 16.9% were obese. 63.8% of the participants were smokers. In 35.8% of participants, hyperglycemia was present, and polycythemia was present in 27.2%. When blood parameters were analyzed, fasting blood glucose, aspartate transaminase, alanine transaminase, and sedimentation rate were lower in those who worked less than five years than those who worked five years or more. The difference was statistically significant. In blood test results, leukocyte, glucose, aspartate transaminase, alanine transaminase, and sedimentation rate values in welders were correlated with total working time. Conclusion: Welders in our study had a high prevalence of smoking, overweight, and obesity. Working time is correlated with liver enzyme levels and fasting blood glucose values. For healthier workers, employers should fulfill their responsibilities for occupational health and safety.

РАСЧЕТЫ ВЛЕКОМЫХ НАНОСОВ С УЧЕТОМ НАИБОЛЬШИХ РАСХОДОВ ВЗВЕШЕННЫХ НАНОСОВ (НА ПРИМЕРЕ РЕК БОЛЬШОГО КАВКАЗА АЗЕРБАЙДЖАНА)

The article analyzes the flow of entrained sediments and their ratio to the highest expenditure of suspended sediments. The study of entrained sediments in mountainous areas is a more difficult task than in lowland areas. In addition, the weak hydrological knowledge of mountainous areas, as well as the lack of observations on the flow of entrained sediments on small rivers, do not allow for full monitoring of entrained sediments. Therefore, the study and calculation of entrained sediments is of great scientific and practical importance. Rolling particles in the largest flow rates of suspended sediments are considered to be entrained, especially when they move during mudflows. It was revealed that the runoff of the entrained sediments has a sorting character in the removal cone according to the Erie law.

Influence of sedimentary processes and fault tectonics on the evolution of submarine canyons in the East Andaman Basin: Insights from high-resolution seismic data analysis

The Andaman Sea Basin, a well-known back-arc spreading centre and a mature petroliferous basin, presents a unique and complex scenario for understanding the interplay of sedimentary processes and fault tectonics on seafloor geomorphology evolution, particularly in the eastern shelf region. This study, using high-resolution 3D seismic data and published exploratory well-seismic interpretation results, aims to establish a comprehensive stratigraphic framework for the Tanintharyi region, spanning the Lower Miocene, Middle Miocene, Upper Miocene, Pliocene, and Quaternary. A submarine canyon system was identified and investigated along the Tanintharyi continental slope within the East Andaman Basin, comprising thirteen slope-confined canyons arranged predominantly in an east-west vertical slope orientation. By analysing seismic reflection features, five distinct seismic facies have been identified, including basal lag (BL), slump and debris-flow deposits (SDFDs), canyon confined sheets (CCSs), laterally inclined packages (LIPs), and channel-levees (CLs). The evolution of this canyon system, a vital focus of this study, can be categorised into three phases based on the morphology and sedimentary structures observed: canyon initiation, canyon extension, and erosion-sedimentation. The findings of this study highlight the critical controlling role of faults in canyon evolution, with the intensity of fault activity displaying a negative correlation with canyon size, indicating the direct impact of faults on geomorphological changes. In addition, the geomorphological changes induced by fault activity have resulted in changes in sediment supply, dispersal, and sedimentation rates, thus significantly impacting the spatial distribution and dimensions of slope-confined canyons within the East Andaman Basin, with far-reaching implications.

Impacts of anthropogenic sedimentation on shell-bed habitats in Lake Tanganyika, Africa

Lake Tanganyika, in central Africa, contains a diverse and endemic fauna under threat from global climate change, overfishing, and nearshore sediment pollution. Previous studies of sediment pollution focused justifiably on impacts along rocky shorelines where diversity is high, but Lake Tanganyika also contains widespread shelly accumulations (shell beds) unprecedented in the modern East African lakes, but where impacts are less constrained. Here we integrate multiple datasets from three sites along the Tanzanian shoreline to explore how variation in sedimentation rates and sediment quality impacts shell-bed substrate and diversity and abundance of ostracodes and sponges across sites that exhibit varying watershed characteristics. Taphonomic overprinting of the shells are similar over the three sites, suggesting lake-wide processes control their accumulation. However, shell bed distribution and sediment volume and compositions vary. There are also differences in the abundance of studied taxa. Where organic matter is diluted by clastic mud, ostracodes are less abundant and less diverse. Where sediment is pervasive and shell density is low, fewer sponges occur. Using the fallout radionuclide 210Pb, the two sites with discontinuous shell beds show sedimentation rates at least twice as high as the site where shell beds are more continuous. These differences are likely related to modest differences in watershed morphology, urbanization, and land cover. Our study suggests that modern sediment pollution creates sediment blankets that cover extant shell beds and likely reduce live populations of the snails that contribute to the accumulations. This has important conservation implications as planning must focus on large watersheds where agriculture and urbanization tend to be higher.

Enhancing the stability of mung bean-based milk: Insights from protein characteristics and raw material selection

Plant-based milk (PBM) alternatives are gaining popularity worldwide as the change of consumers' nutritional habits and health attitudes. Mung beans, recognized for their nutritional value, have gained attention as potential ingredients for PBM. Nevertheless, mung bean-based milk (MBM) faces instability issues common to other plant-based milks. This study investigated the factors influencing MBM stability focusing on raw materials. We selected 6 out of 20 varieties based on their MBM centrifugation sedimentation rates, representing both stable and unstable MBM. Stable MBM exhibited distinct advantages, including reduced separation rate, smaller particle size, lower viscosity, fewer protein aggregates, higher soluble protein content, and increased consumer acceptance. Major nutritional components such as protein, starch, and lipids were not significant different between stable and unstable MBM varieties. The pivotal distinction may lay in the protein properties and composition. Stable MBM varieties exhibited significantly improved protein solubility and emulsion stability, along with elevated concentrations of legume-like acidic subunits, basic 7S proteins, and 28 kDa and 26 kDa vicilin-like subunits. The increasement of these proteins likely contributed to the improvement in protein characteristics that affect MBM stability. These findings offer valuable insights for raw material selection and guidance for future mung bean breeding to enhance mung bean milk production.

Taxonomy, paleoecology, and paleobiogeographical significance of the middle-late Eocene molluscs from the Garet Gehannem section in the Fayoum depression, Egypt

The studied middle-upper Eocene Garet Gehannam section exhibits moderate macrofossil diversity and notably high macrofossil abundance. Eleven molluscan species were identified and described, including five bivalves and six gastropods. Three macrobenthic assemblages were recognized: The turritelline-dominated assemblage, Carolia placunoides assemblage and Turkostrea multicostata assemblage. The Turritelline-dominated assemblage indicates high-nutrient environments, which typically exhibit normal to slightly below normal marine salinities, low sedimentation rates, and high-energy environments. Carolia placunoides assemblage indicates brackish water environment during times of sea level regression. Turkostrea multicostata assemblage provides compelling evidence of a prevailing hot climate and an environment rich in calcium, characterized by nutrient-rich water and low to moderate energy levels and high light availability. The investigation of the articulation of Carolia placunoides Cantraine1838 and Turkostrea multicostata (Deshayes, 1818) shells strongly suggests a parautochthonous assemblage. In terms of paleobiogeography, Turkostrea multicostata (Deshayes, 1818) first appeared during the Paleocene in the southern Tethys, specifically in Tunisia and Algeria, as well as in the Trans-Saharan Seaway in Mali. Consequently, its paleobiogeographic distribution can be allied to current circulation along the Tethys Ocean, firstly from its original area in the southern Tethys regions and Trans-Saharan Seaway to neighboring regions of the southern and northern Tethys, as well as the West Africa provinces. The paleobiogeographic map of the identified species shows that the identified species were prevailing in two bioprovinces during the middle – late Eocene epochs: i) the North-West, North, and South Tethyan Margins Province, ii) and the West Africa Province.

System-scale dynamics of long-term sediment and phosphorus accumulation in contrasting valley-bottom wetlands in dryland landscapes of South Africa

Anthropogenic-induced acceleration of sediment and associated nutrients presents a serious challenge to water resource management across the globe. While wetlands are potential natural solutions, little is known of how well key wetland types attenuate downstream sediment fluxes and how these relate to local- and catchment-scale factors. This research aimed to develop an understanding of patterns and rates of sediment and phosphorus retention in valley-bottom wetlands in South Africa. The geomorphology, sedimentology and historical accretion rates of three wetlands which offered diversity in size, catchment position and degree of organic accumulation were compared to ascertain the impact of local- and catchment-scale factors. Estimates of sediment and associated phosphorus accumulation suggest higher rates in clastic sediment-dominated wetlands (1089–7655 g sediment m−2 yr−1, 0.4–1.6 g-P m−2 yr−1) compared to an organic sediment-dominated system (601–1308 g-sediment m−2 yr−1, 0.2–0.3 g-P m−2 yr−1). Sediment accretion rates generally increased longitudinally, indicating that distal wetland reaches act as sediment and phosphorus retention hotspots. Phosphorus distribution patterns were primarily attributed to variations in organic matter content and associated aluminium and iron complexing agents in fine-grained sediment deposits, while particle size distributions were less important. However, the relevance of individual complexing agents in phosphorus dynamics varied among wetlands with differing landscape conditions. Contrasts between these systems reflect variations in catchment lithology and hydroclimatic regime, which influence the relative magnitude of sediment supply and vegetation productivity. We postulate that intermediate-sized wetlands characterised by catchments around 900 ha in size, gentle longitudinal slopes (∼2 %), a high proportion of fine sediment deposition, limited organic matter breakdown, and a long vegetation growing season provide optimal conditions for sediment and phosphorus accumulation. This system-scale information is essential to guide management decisions to identify and prioritize within-catchment ‘hotspots’ of sediment and phosphorus retention.

Estimating the useful life of the sempor reservoir using erosion modelling

Sedimentation determines how optimal a reservoir functions throughout its design life. The Sempor Reservoir in Central Java, Indonesia, will be 45 years old in 2023. At least 15 million m3 of particles have been sedimented in the reservoir for >30 years, reducing its function as an irrigation water source to only 60%. Therefore, assessing its performance in providing irrigation water and generating hydropower electricity is essential, given that its design life ends in 2028. This study was conducted to analyse the sedimentation and estimate the useful life of the Sempor Reservoir based on the erosion potential in its catchment area. The potential sedimentation rate was formulated from erosion potential assessed using the universal soil loss equation (USLE) model, sediment delivery ratio (SDR) and trap efficiency (TE). By contrast, the actual sedimentation rate was determined from changes in the dead storage capacity from 2013 to 2023. The interpolation performance evaluation of the bathymetric survey results was tested using the coefficient of determination (R2), Nash-Sutcliffe efficiency (NSE), and mean absolute percentage error (MAPE) which resulted in values of 0.917; 0.87; and 13.03%, respectively. The results show that the catchment area had an erosion potential of 3,405,353.86 t∙a−1, resulting in a potential sedimentation rate of 309,106.63 m3∙a−1. The calculated actual sedimentation rate was 33,903.28 m3∙a−1. Therefore, the useful life of the Sempor Reservoir was estimated to end in 0.5 years and 4.59 years based on the potential and actual sedimentation rates, respectively.

Pleistocene deformation of the Malargüe fold–thrust belt from structural modelling and geochronology of syntectonic sedimentation

We report uplift and shortening rates from a late Neogene–Pleistocene deformation stage of the frontal fold–thrust belt and adjacent wedge-top in the Principal Cordillera of the southern Central Andes (latitude 33–39°S). A structural model is presented based on integration of surface field data and subsurface 2D seismic sections. Shortening, uplift and sedimentation rates were calculated from different steps of kinematic modelling. Our structural interpretations and modelling are integrated with new detrital zircon U–Pb geochronology to define a previously overlooked Pleistocene period of orogenic shortening and syntectonic sedimentation in the Malargüe basin. This task was possible as a result of the dating of three samples yielding ages between ∼12 and 1 Ma obtained from a 900 m deep well located in the foreland. From stratigraphic correlations, our data record an active Plio-Pleistocene wedge-top depozone coeval with retreat of the volcanism, and the emplacement of retroarc basalts. Structural modelling, together with detrital zircon U–Pb provenance data, registers shortening producing a foredeep to wedge-top Plio-Pleistocene transition, adjusting and completing the knowledge of the frontal fold–thrust belt and foreland basin in the southern Central Andes. Supplementary material: Supplementary tables are available at https://doi.org/10.6084/m9.figshare.c.7033425

A comparative analysis of missing data imputation techniques on sedimentation data

Sediment data pertains to various hydrological variables with complex sediment hydrodynamics such as sedimentation rates which are often incompletely presented. Thus, the availability of sedimentation data is of utmost necessity for data accessibility. A comparative analysis on the missing fine sediment data imputation performance was made based on four different techniques, namely the k-Nearest Neighbourhood (k-NN), Support Vector Regression (SVR), Multiple Regression (MR), and Artificial Neural Network (ANN), under the single imputation (SI) and multiple imputation (MI) regimes. Across different missing data proportions (10%-50%), the ANN demonstrated optimal results with consistent performance metrics recorded over both SI and MI regimes. For the highest missing data proportion (50%), the ANN presented the best imputation performance with a reported root mean squared error (RMSE) 0.000882, mean absolute error (MAE) 0.000595, coefficient of determination (R2) 71%, and Kling-Gupta Efficiency (KGE) 72%. The imputation performance ranking is as follows: ANN, SVR, MR, and k-NN.

Morphologic Adjustment of a River Reach with Groynes to Channel Bypassing

AbstractThis article is focused on the investigation of the spatio-temporal variability of the Danube River reach’s vertical accretion thickness due to the response of the Danube River reach to bypassing. Five groyne-induced benches (GIBs) of the bypassed channel developed after water diversion in 1992 was studied by changes in topography for three-time spans (for the original gravel surface, for the surface before the 2013 flood and for the surface after the 2013 flood). The allostratigraphic approach was applied to 548 drilling probes at all GIBs and toptop, supra-platform, tail and backchannel geomorphic units have been identified at each GIB. The main to side-channel system connectivity increase sedimentation rates and the accretion was controlled by large flood events. The 100-year flood in 2013 contributed to the total volume by almost 26%. During study period 1992–2017, totally 1,146,589 m3 was accreted on five GIBs, of this 209,752 m3 during flood event in 2013 and 267,700 m3 in post flood period 2014–2017. The top geomorphic unit exhibits the highest median values of vertical accretion and for all GIBs accretion thickness are not related to the height above the mean channel water level. The thickness of accretion varied, likely because the variability of the vegetation cover caused variable hydraulic conditions and accretion rate span from 3.8 cm.year−1 to 5.3 cm.year−1. The investigation of the sediment thickness over long time spans 24 years and a large flood event) allowed us to conclude that the thickness is spatially variable for individual GIBs; however, its trend over time remains constants depending on the intake of sediments during large floodsd events. This article also provides a methodological template for the detailed investigation of river channel adjustment due to bypassing.

Reservoir siltation and sediment characterization for reuse as construction material in a semi-arid area

Anibi S, Ellouze S, Zairi M. 2024. Reservoir siltation and sediment characterization for reuse as construction material in a semi-arid area. Lake Reserv Manage. 40:159–176. In this study, we investigated the siltation rate, evolution, and spatial distribution of sediments within the Siliana Dam reservoir, north-west Tunisia. We analyzed the geotechnical, chemical, mineralogical, and trace metal content properties of sediment samples collected from the reservoir. Additionally, we examined the potential valorization of reservoir sediments in road construction and the effects of hydrated lime treatment on their bearing characteristics. The Siliana dam reservoir is currently 50% silted up, and the sedimentation rate is approximately 1.52% per year. The sediments are mainly fine-grained, low organic with medium to high plasticity and high content of calcium carbonate. The sediments consist of calcite and quartz, with minor amounts of dolomite, hematite, and phyllosilicate minerals. Chromium, zinc, and copper contents in the sediments exceed environmental standards. The lime treatment improved the materials bearing capacity. Adding lime (5% by weight) resulted in an immediate bearing ratio of 26%, a higher ratio compared to the raw sediments. The study of the spatial and temporal evolution of sediment accumulation provides information to develop strategies for mitigating the accumulation of sediments. The sediment characterization evaluated the suitability of sediments to be used as construction materials, offering potential cost savings and contributing to informed decision-making for reservoir management.

Variable downcanyon morphology controlling the recent activity of shelf-incised submarine canyons (Alboran Sea, western Mediterranean)

This research aims to distinguish genetic sedimentary processes building canyon geomorphological patterns and the factors driving different sedimentary activities in two nearby Mediterranean shelf-incised submarine canyons (Carchuna and Motril) that exhibit different degrees of incision on the narrow margin of the northern Alboran Sea.The straight Carchuna Canyon incises the shelf up to 200 m off the coastline and exhibit steep canyon walls featuring narrow terraces, muddy sands with high contents of organic matter along the thalweg, and transported shelf benthic foraminifera in distal settings. The Motril Canyon head is wider and incises the shelf edge, ca. 2 km off the coastline. It exhibits a sinuous morphology and less steep walls, wider terraces, and higher sedimentation rates with muddy sediments along the thalweg. In both canyons, cross-section relief, width, incision, and area decrease downslope, although these parameters increase locally.The downslope variations of geomorphological parameters are attributed to enhanced erosional/depositional processes promoted by tectonically controlled abrupt changes of the axial channel orientation. The degree of shelf incision, the location of the canyon heads in relation with the local sediment sources, and the seasonally variable hydrodynamic regimes determine the different degrees of recent canyon activity. The Motril Canyon is interpreted as a mature system that reflects episodic activity, collecting fine-grained sediments from the nearby Guadalfeo River. The Carchuna Canyon exhibits a youthful developmental stage whose activity is more continuous and involves sediment trapping of littoral cells and continuous downslope sand transport.

Development of Suspended Sediment Rating Curve Model by Statistical Classification of River Discharge Data (Case Study: Ghareh-Sou Coastal Watershed)

Development of Suspended Sediment Rating Curve Model by Statistical Classification of River Discharge Data (Case Study: Ghareh-Sou Coastal Watershed)

Modification of rain and run-off erosivity to predict erosion hazard level on The Manguan Sub-watershed’s Upper Slope

To protect natural resources and maintain the normal functioning of hydrological processes, the upper slope of the Manguan Sub-watershed should be designated as a conservation area. However, agricultural activities in the upstream have disrupted the watershed’s hydrological function, triggering high rates of erosion, sedimentation, and flooding. The aim of this research was to estimate the level of erosion hazard on Manguan Sub-watershed’s Upper Slope and its conservation directives to mitigate it. This study adopted a land unit approach to flow occurrence land units with the prediction of MUSLE (Modified Universal Soil Loss Equation) by integrating rainfall and run-off erosivity. The direction of land conservation will be evaluated through the perspectives of land rehabilitation and soil conservation. Based on the result, the prediction of erosion hazard levels is classified into four groups: Low, Moderate, High, and Extremely High. The Manguan Sub-Watershed’s Upper Slope has a significantly high level of erosion and necessitates soil conservation improvement measures on approximately 79% of its area.

Comparison of sediment and water column nutrient processing rates in agricultural streams of contrasting buffer land use

AbstractWatershed nutrient management often focuses on actions that reduce the movement of nitrogen (N) and phosphorus (P) from agricultural lands into streams. One area of management focus is the buffer of land adjacent to streams. Wetlands and forests in this buffer can intercept and retain N and P from the landscape. In addition to directly intercepting agricultural nutrients, natural habitats in the buffer can alter stream geomorphology and influence the in‐stream processing and transformation of N and P to less labile and mobile forms. Here, we assess the influence of buffer land cover on in‐stream processing of N and P. We measured nutrient dynamics in the water column and sediments of agricultural streams in the Fox River and Duck Creek watersheds (WI, USA) during the growing season. In these streams, water column processing was low, possibly due to a lack of primary producers in the water column. Water column P processing was weakly associated with wetland land cover in the buffer, but buffer land cover had no clear effect on inorganic N processing. On the other hand, sediments were almost always a source of inorganic P and a sink for inorganic N. Sediment P release was higher in streams with more agricultural land cover in the buffer. Sediments in streams with agricultural land cover in the buffer also removed more nitrate, even after accounting for the greater availability of nitrate in those streams. The buffer land cover conditions we quantified occupy a very small portion of the overall watershed (100 m wide, for 1 km upstream of the study site) but nevertheless appear to influence in‐stream cycling of N and P. For P management, reducing agricultural land cover in buffers is already a priority due to the ability of wetlands and forests to intercept nutrients, but this study suggests there may be some additional benefit due to changes in in‐stream P processing.

Dimensional analysis for sedimentation behavior of magnetorheological fluids

Magnetorheological fluids (MRFs) are primarily composed of magnetic particles suspended in carrier liquids, exhibiting a remarkable capacity to respond dynamically to external magnetic fields. However, the phenomenon of solid–liquid phase separation, attributable to particle sedimentation, represents a formidable barrier to the real-world application of MRFs in engineering contexts. As a result, it becomes critically imperative to conduct a thorough investigation into the sedimentation behavior of MRFs under static conditions, to significantly enhance their practical utility. In the study, computational analysis through COMSOL was utilized to elucidate the sedimentation dynamics of MRFs. The findings indicated that particle sedimentation harbored the potential to induce localized turbulence within the flow field, thereby significantly impacting the sedimentation dynamics of MRFs. The motion of particles consistently followed a pattern where sedimentation rates decreased as the viscosity of the carrier liquids increased. Moreover, the elucidation of the settling behavior of MRFs was facilitated by the introduction of two dimensionless numbers. These dimensionless numbers were employed to systematically characterize the temporal evolution of the supernatant height throughout the settling process. This investigation further explored the intricate interdependence between these dimensionless parameters via a comprehensive series of settling experiments. The outcomes of this research uncovered a unique pattern in the solid–liquid separation process of MRFs, marked by a phase of gradual initiation, followed by acceleration, and culminating in deceleration. However, as the viscosity of the carrier liquids increased, this pattern became less pronounced, gradually shifting toward a more uniform settling trajectory.

The analysis of degradation and aggradation of the riverbed: A case study of the Winongo River

The Winongo River, with a soil base, makes it possible to experience sedimentation events. In rivers with groundsill for retaining sediment rate, the flow can occur, grinding sediment (degradation) or aggradation on the riverbed. This study was conducted in Winongo River to see the effect of groundsill on riverbed degradation and aggradation levels. This research was carried out using the MPM, Engelund & Hansen, and Laursen-Copeland equations in HEC-RAS 6.3.1 by dividing Winongo River into 71 points with a spacing of ± 500 m, including nine with groundsills. Based on the effect of the groundsill on the riverbed, the cross sections at its upstream and downstream tend to experience quite different riverbed elevation changes. Conditions in the upstream groundsill tend to experience aggradation while the downstream experiences degradation. The three equations modelling results show that MPM and Engelund & Hansen equations are closer to field conditions than the Laursen-Copeland equation. The use of D50 sediment to model changes in riverbed elevation is more likely to experience degradation because the average grain size of D50 in this study sample was 0.82 mm.

Analysis of the Rate and Nutrient Content of Sediment in The Coral Transplantation Installation Vertical Method on Samalona Island, Makassar City

Samalona Island is a small island that administratively belongs to the inner zone of the Spermonde Islands region with low live coral cover. One effort to improve coral conditions is to carry out vertical transplantation, but hydro-oceanographic conditions are thought to be an inhibiting factor, including sediment. The research carried out aims to determine the suitability of oceanographic parameters, estimate sediment rates, and determine the phosphate and nitrate in sediments. The research method used a field experiment method by taking water and sediment samples and installing sediment traps for 15 days. The parameters measured in situ are temperature, pH, current speed, salinity, and dissolved oxygen, while the ex-situ test is the dry weight of sediment, TSS, nitrate, and phosphate concentrations. Data analysis uses descriptive statistics and is categorized according to the evaluation instrument used. The research results show that the values for temperature, pH, current speed, salinity, and dissolved oxygen meet the standard criteria for coral-based on PP 21/2022. The sediment rate during the research period was 0,003 – 0,015 gr/cm2/day, so it was categorized as having the potential damage to corals with a mild to severe impact level. The nitrate concentration in sediment ranges from 0,19 – 0,25 ppm while phosphate ranges from 0,35 – 0,72 ppm, so it can be said to be waters with a medium trophic level (mesotrophic). The current speeds and sediment rates potentially accelerate nutrient concentrations and cause sediment resuspension, thereby closing coral polyps, especially on corals closest to the substrate where vertical coral transplant installations are installed.