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Abstract Water plays a significant role in every sector of the ecosystem. The fluctuation of the water levels in lakes is influenced by natural and man-made factors within the water catchment. Lake Baringo, which has no visible outlet, has been rising drastically, causing panic among native communities and businesses on the shores of the lake. Using GIS and Remote Sensing, this study intends to analyze the changes in water lakes using the Automatic water extraction index (AWEI), determine the causes of the fluctuation using Land use Land cover, land surface temperature, soil erosion, and siltation in the lake basin and the lake respectively, precipitation, and later predict of the water level for the year 2030 using the MOLUSCE tool. The tool utilizes an artificial neural network and cellular automata to analyze land use and land cover conveniently. It was found that the lake’s water level has been increasing drastically over the years, and the leading causes of the fluctuations were increased rainfall and human activities within the water basin. There are visible increased human activities within the water basin, such as agriculture, deforestation, settlement, and urbanization. It was also found that there will be a further increase in water level in 2030. With all the above results, it is recommended that better policies be made to conserve the water basin effectively, and a plan should be drawn to re-delineate the new riparian buffer.

Hard river engineering or channelization alters channel bathymetry and river morphology and invites multiple fluvio-hydrological hazards. The linear (72 m), concrete, low height (1.6 m), multipillars (20 pillars) bridge with concrete embankments and revetments has been constructed across and along the river Bala within the Himalayan foothill zone in the year 2017. As a result, the rate of siltation has been tremendously increased at the vicinity of the pillars of the bridge. The principal objectives are (i) to establish wrongly designed hard river engineering techniques and (ii) to find out the adverse effect of Bala bridge. Results showed that the highest rate of siltation was 0.55 m at the end of the monsoon in 2017 whereas the average of rate of siltation was 0.37 m between 2010 and 2017. If the rate of siltation is greater in a particular year, there is a high probability to divert the channel course. The thalweg line has tremendously shifted towards the right bank side. If the same condition persists for a long time, in near future (during monsoon) the river will avulse nearly 200 m right side on low lying topographic depression within the rich Buxa Tiger Reserve.

Reservoir siltation lowers a dam’s effective storage capacity, which is mostly determined by the sediment discharge from soil erosion in the watersheds. The morphometric parameters are significant in determining erosional susceptibility of watersheds. In the present study, morpho-hypsometric aspects of the Surya sub-basin, a major tributary of Vaitarna river, has been considered. This river system and associated dams provide the major source of drinking water supply to the Mumbai Metropolitan Region (MMR). A major part of the river flows through the Deccan Volcanic Province (comprising basalts) and Quaternary alluvial deposits. The seven sub-watersheds (SWs) of Surya sub-basin were analysed using the morphological parameters (linear, areal, and basin shape aspects), along with ratio factors and hypsometric integral (HI) values. The HI values for the SWs range from 0.11 (SW-1) to 0.51 (SW-6) with a HI value of 0.21 for the whole Surya sub-basin. The relatively high HI values of SW-6 (0.51) and SW-7 (0.31) indicate that these SWs are relatively prone to high erosion and sediment discharge resulting in dam siltation, and will be a great threat to livelihood of millions of people in the MMR. Therefore, prioritizing these SWs for proper engineering measures could reduce erosion and improve recharge.

Water plays a significant role in every sector of the ecosystem. The fluctuation of the water levels in lakes is influenced by natural and man-made factors within the water catchment. Lake Baringo, which has no visible outlet, has been rising drastically, causing panic among native communities and businesses on the shores of the lake. Using GIS and Remote Sensing, this study intends to analyze the changes in water lakes using the Automatic water extraction index (AWEI), determine the causes of the fluctuation using Land use Land cover, land surface temperature, soil erosion, and siltation in the lake basin and the lake respectively, precipitation, and later predict of the water level for the year 2030 using the MOLUSCE tool. The tool utilizes an artificial neural network and cellular automata to analyze land use and land cover conveniently. It was found that the lake's water level has been increasing drastically over the years, and the leading causes of the fluctuations were increased rainfall and human activities within the water basin. There are visible increased human activities within the water basin, such as agriculture, deforestation, settlement, and urbanization. It was also found that there will be a further increase in water level in 2030. With all the above results, it is recommended that better policies be made to conserve the water basin effectively, and a plan should be drawn to re-delineate the new riparian buffer. [ABSTRACT FROM AUTHOR]

The marine environment in Tanzania faces significant pollution originating mainly from land-based sources such as industrial, agricultural, and municipal waste, as well as coastal construction, oil discharges, and dredging activities. Siltation, a significant problem in the Dar es Salaam harbor, has led to a decrease in the depth of the entrance channel, requiring more frequent dredging.

Purpose: is to assess the actual water volumes in water objects (reservoirs, lakes, ponds) to identify the degree of maximum anthropogenic load, namely, the pollutant release. Materials and methods. Lake Svyatoe, located in Kosino-Ukhtomsky administrative district of Moscow, was chosen as the research and experimental object for testing the automatized system. The programs Google Earth Pro, Surfer 22, local author's programs for data processing, author's unmanned surface vehicle (USV), echo sounder Garmin Striker Cast GPS were used in the study. Automated systems as an unmanned surface vehicle (unmanned boat – USV), sensors (including echo sounder) and local programs for data acceptance and processing can be applied to improve and organize continuous monitoring of water objects. Results. The actual water volume assessment in the water object of 215 thousand cubic meters by means of the USV and its mounted echo sounder was demonstrated. The methodology of the unmanned boat operation for the water resources exploration was developed. Conclusions. Taking Lake Svyatoe as an example of water resources volume survey, it can be concluded that the methodology is applicable to any other water body, including reservoirs. Through regular water resources survey using USV it is possible to record not only changes in the actual water resources volume, but also bottom relief changes, sedimentation or overgrowing processes at specific sites. It also allows calculating the maximum allowable anthropogenic impact on the given object, including the maximum allowable discharge and its intensity at a particular moment of time.

This research conducted a citizen scientific field investigation and water quality assessment of nine major rivers using only on-site equipment and a smartphone in the Province of Antique, Philippines. Potential issues concerning water resources management in the province were discussed with local governors and citizens while conducting the water sampling and on-site measurement. The results of water quality assessments revealed that some of the rivers have experienced high turbidity, caused by anthropogenic activities such as embankment, sand mining, and dredging. In highly populated basins, such as the Sibalom and Malandog Rivers, a high biochemical oxygen demand level (>7 mg/L) was confirmed by the water quality analysis using an iPhone. Since high consumption of groundwater has already affected the lives of people in the province, surface water usage shifting from groundwater, involving the construction of a facility treating physical and chemical parameters, is needed. The citizen scientific approach employed in this research can provide more realistic insights into local environmental concerns, which would not be possible through quantitative measurements of water quality. HIGHLIGHTS The water quality of nine major rivers was assessed in the Province of Antique, Philippines.; Citizen scientific field investigation and water quality analysis used only an iPhone and an on-site water quality meter.; Some rivers have experienced siltation caused by anthropogenic activities.; A high biochemical oxygen demand level was confirmed in highly populated basins.; There is a need for a shift from groundwater to surface water usage.;

The accumulation of silt in water dams is a natural phenomenon and an acute problem, and every year, about 4,000 tons of soil per square kilometer goes to the dams or the sea through valleys, causing the dams to become saturated with silt or sanding the ports, coinciding with the shrinking of agricultural areas. In general, the siltation of water dams results from a complex process characterized by four successive stages, namely, runoff, erosion, transport, and sedimentation. In this field, many specialists have presented their approach to the problem of sediment transport and erosion, which can affect silt in the area, and therefore, it is important to know the rate of silt before completing the dams. In addition, many factors affect the siltation of dams, such as runoff. In this regard, this article deals with a meta-study of the relationship between the silt rate in Algerian dams and the surface runoff factor. This is to obtain a database that can be used by research professors as well as experts supervising the construction of dams in Algeria. HIGHLIGHTS The problem of siltation rate in Algerian dams and which factors which can influence the rate of siltation.; Calculate the siltation rate of each dam and the coefficient of the runoff rate of each watershed.; Find the graphical relationship.; Try to make a database that can be used in future research.; Give the recommendation.;

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos (e.g. brachiopods, corals, bryozoans, foraminifers, ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ∼55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high temperatures. Other kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation (burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes (

Monitoring sediment transport in a run-of-river hydropower dam was investigated to detect and quantify the siltation processes using Sentinel-2/MSI satellite images. We developed a method allowing us to assess the fate of sediment discharge in reservoirs and to map the locations of eroding and silting stream cross sections. This monitoring was achieved by retrieving the seasonal and interannual variation in suspended sediment concentration (SPM) longitudinally and by developing indices to detect local deviations from the overall SPM trend. A comparison between Sentinel-2 reflectance, processed for atmospheric and glint correction, and field measurements showed fine accuracy for the b8a/b4 band ratio (RMSE = 0.23 sr-1, N = 50) as well as a very good SPM retrieval performance for a wide range of concentrations [10–926 mg/L] with an RMSLE of 0.23 mg/L. SPM trend analysis demonstrated that significant (p

Riverbed clogging is key to assessing vertical connectivity in the hyporheic zone and is often quantified using single‐parameter or qualitative approaches. However, clogging is driven by multiple, interacting physical and bio‐geochemical parameters, which do not allow for a conclusive assessment of hyporheic connectivity with single‐parameter approaches. In addition, existing qualitative assessments lack transparency and repeatability. This study introduces a Multi‐Parameter Approach to quantify Clogging and vertical hyporheic connectivity (MultiPAC), which builds on standardized measurements of physical (grain size characteristics, porosity, hydraulic conductivity) and bio‐geochemical (interstitial dissolved oxygen) parameters. We apply MultiPAC at three gravel‐bed rivers and show how the set of parameters provides a representative appreciation of physical riverbed clogging, thus quantifying vertical hyporheic connectivity. However, more parameters are required to fully characterize biological clogging. In addition, MultiPAC locates clogged layers in the hyporheic zone through multi‐parameter vertical profiles over the riverbed depth. The discussion outlines the relevance of MultiPAC to guide field surveys. [ABSTRACT FROM AUTHOR]

India is the world's second-largest producer of fish, where the state of West Bengal is leading in fish production. The Sundarbans, located in the southern part of India's West Bengal state, is a UNESCO-designated world heritage site. The Indian Sundarbans is a tide-dominated region in the southern part of deltaic West Bengal, and is home to 4.43 million people. Even though it is traversed by numerous creeks and rivulets and receives a significant amount of precipitation during the monsoon season, freshwater is a scarce resource in the Sundarbans. During the dry season, there is a lack of fresh water above and below the ground, increasing siltation results in shallower channels, high salinity of the water and soil, and congestion in drainage making it difficult for people to make a living. During the dry season, most blocks experience water scarcity as a result of the ever-increasing population's demand for water. According to this study, Sundarbans' current annual domestic and drinking water demands are 105.1 mcm and 8.08 mcm, respectively. By combining the area under various crops and their lifecycle water requirements, the water demand for agriculture has been calculated to be 2782.83 mcm. The rainfall-runoff modelling aims to get a general idea of how much fresh water is available each year through surface runoff. It has also been estimated how much water is available from different sources in each block. It is estimated that deep and shallow bore wells contribute approximately 400 mcm, whereas surface water sources like tanks and canals contribute approximately 50 mcm. The communities that live in the Sundarbans eco-region benefit greatly from aquaculture's contribution to their socio-economic development. For the sustainable development of aquaculture in the Sundarbans Delta, strong technical, financial and extension services from government organisations and research institutions are urgently required to meet these obstacles. Additionally, this study emphasises that roof-top rainwater harvesting in this region has the potential to supply 45 mcm more water, which could be used to partially satisfy the region's domestic water demand. Future major policy options for meeting the Sundarbans ecoregion's water demand include large-scale rainwater harvesting, rejuvenation and reconnection of disconnected river channels, artificial recharge of shallow aquifers to lower their salinity, and de-salination of shallow groundwater. [ABSTRACT FROM AUTHOR]

Channel dredging in estuaries increases water depth and subsequently impacts sediment dynamics and morphology. The Jiaojiang River Estuary is dredged frequently owing to heavy shipping demands. In this study, the effects of different dredging schemes on siltation were assessed through numerical modeling. The sediment model of the Jiaojiang River Estuary utilized an optimized bottom boundary layer model that considered the bed sediment grain size and fluid mud, and this model was calibrated using field data. Result reveal that channel dredging modifies the flow velocity inside and around the channel by changing the bathymetry; subsequently, this affects the residual current, bed stress, suspended sediment concentration, and sediment fluxes. Increasing the dredging depth and width increases the net sediment fluxes into the channel and dredging depth has a greater influence on the channel siltation thickness. When the dredging depth is 8.4 m or11.4 m, the average siltation thickness of the channel is 0.07 m or 0.15 m per mouth respectively. The parallel movement of the channel has small effects on the siltation volume during the simulation period. The sediment deposits in the channel primarily originates from the tidal flats, through bottom sediment fluxes. Vertical net circulation has a dominant impact on siltation because the difference of horizontal current of each layer on the longitudinal section of the channel increases, which intensifies the lateral sediment transport between the shoal and channel. The influence of vertical frictional dissipation on the lateral circulation at the feature points accounts for more than 50% before dredging, while the non-linear advective term is dominant after dredging. Tidal pumping mainly affects the longitudinal sediment fluxes in the channel. These results can be used for channel management and planning for similar estuaries worldwide. [ABSTRACT FROM AUTHOR]

Relevance. Cleaning of reclamation channels is a very relevant event. The need to clean the canals and maintain them in working condition becomes obvious during the flood period, when it is necessary to remove excess water. The paper presents mathematical models for determining the performance of the PP-303 canal cleaner, a feature of which is the rectilinear movement of the bucket on rigid guides along the bottom along the axis of the canal to be cleaned.Methods. The article is formed on the basis of experimental research methods. The research was carried out based on experimental and calculated data. A network of drainage canals of the drainage system was taken as the research object, and the working equipment of the canal cleaner was taken as the research subject. Performance, which is the amount of products produced by the machine per unit of time, can be of three types (theoretical, technical, and operational) and can be determined with consideration of the design parameters of the working equipment. During the operation of trench cutting machines, their performance directly depends on the main parameter, namely, the depth of the canal being built; in the case of canal cleaning with canal cleaners, this parameter cannot be considered as the main one. This is due to the fact that siltation and sediments accumulating on the bottom and slopes of the canals during the operation of the reclamation system are extremely unevenly distributed along the length of the canal. The highest concentration and amount of sediments and siltation is observed mainly at the mouth of the canals, the junctions of canals of different levels, and the junctions of the drainage with the drainage canal. In this case, the most significant parameter is the thickness of the chips removed from the bottom and slopes of the canal by the bucket.Results. The results of the research showed that the performance of the channel cleaner, as a batch machine, is influenced by the very design of the working equipment, the main element of which is a bucket capable of moving in a straight line along rigid guides at different speeds. With obvious high values of the performance of continuous channel cleaning machines, it can be concluded that the channel cleaner RR-303 showed high values of technical and operational characteristics, mainly due to the use of a trapezoidal profile bucket.

Due to advanced silting, the Foum El-Gherza dam has lost more than two thirds of its initial capacity (47 hm3 ) and is no longer able to withstand the floods that threaten its downstream section. Indeed, the damage recorded in recent years has confirmed the vulnerability of the manmade structures located on both banks of the Oued abiod. Thus, we believe that the hydrological behaviour of the catchment area is no longer influenced by the dam. Therefore, the hydrological study involved a critical analysis (homogeneity tests) of the hydro-climatic data in order to highlight the characteristics of the historical events recorded during the period 1950–2019. The frequency study of the maximum daily rainfall and floods recorded at the dam allowed us to determine the rainfall and flow rates of the return periods (10, 25, 50, 100, 500 and 1000 years). The flooding of the 28 October 2011 were used as a standard for the calibration of the model calculated by the HEC-Ras software. After validation of the model, a prediction of the water levels and flood extent was made for the selected return periods. The results obtained show that a part of the town of Seryana (district located on the edge of the right bank) suffers from flooding proportionally to the return periods of the floods. In addition, some agricultural areas bordering the Oued are also affected by the floodings. The hazard modelling maps can be considered as a basis for a flood risk prevention plan (PPRI) and as a decision support tool. [ABSTRACT FROM AUTHOR]

The objective of the current work is to determine the amount of sediments transported upstream and at the level of Oued Fodda dam. The latter is considered one of the first large dams built in Algeria. It's exposed to a serious siltation problem that reduces its capacity every year. The simulation was executed using the HEC-RAS software, for the period varied from January 01, 2016 to April 30, 2016. The modeled section consisted of about 9999 m length, subdivided into 141 river stations distant from each other by 70 m. The observation of the studied river section bed- profile was selected as a criterion for comparing the results of the model with the real values observed. A roughness coefficient of 0.031 was used. A quantitative estimate with a determination coefficient, R2, of 0.92 was used to support the validity. The mass and concentration of sediments increased significantly in the crosssections located at the dam upstream. A total cumulative mass was estimated at approximately 712699 tons, just upstream of the dyke, and a maximum concentration of 22.35 g/l was observed, particularly for three main sections selected upstream of the Fodda wadi. However, at the reservoir level, the concentration variability is observed during flood periods, i.e., only for the most important flows. [ABSTRACT FROM AUTHOR]

The Djorf Torba dam belongs to the arid zones and is losing its performance due to a combination of natural and anthropogenic constraints. Indeed, the correlations between rainfall stations are contrasted (r − 0.2 to 0.97), reflecting a strong heterogeneity of rainfall in the same basin. The SPI shows that the basin is subject to recurrent and persistent drought years. Drought conditions predominate in terms of frequency, 58% of years (1972/73 to 2017/2018). In contrast, wet periods are limited to 42% of the total series. For the period from 2009/10 to 2017/18, which is very significant for the water stock of the dam, drought frequencies increase to 69%, and wet periods decrease to 31%. This dam is not spared from siltation, which impacts storage capacity; the 1986 bathymetric survey showed a loss of 09.4% of its original capacity. The loss in volume is 1,976,470 m3/year. The second survey in 2004 indicated a loss of 25.64% of its initial capacity. Siltation forecasts indicate that by 2020 the siltation rate will be 33.29%. The water supply volume in 1999/2000 was 8.78 Mm3/year, increasing to 10.38 Mm3/year in 2014/2015 and 18.06 Mm3/year in 2019/2020. This dam is subject to a persistent drought due to insufficient precipitation and runoff compared to expected or normal values. Its storage capacity is constantly decreasing and has been reduced by more than 1/3 of its initial capacity. At the same time, there is increasing use of the stored water. This state of affairs prompts us to reflect on the effectiveness of constructing large dams in arid zones. [ABSTRACT FROM AUTHOR]

Siltation of dams appears as an urgent global concern, especially in arid and semi-arid regions concerned by the challenges of managing their limited water resources. These challenges worsen by the increase in water demand driven by population growth, aggravated by the adverse effects of climate change, in particular the siltation of dam reservoirs. This article focuses on the spatiotemporal analysis of the accumulation of sediments in Moroccan dam reservoirs. The methodology involves the collection, verification, correction, and interpolation of bathymetric data, which are organized and visualized in temporal and spatial dimensions using a dedicated Geographic Information System (GIS). The spatial distribution maps generated facilitate the identification of the area most severely impacted by the siltation of dams. The analysis emphasizes that siltation affects all Moroccan watersheds, with a particular emphasis on the Moulouya watershed due to the characteristics of its soil and its arid climate, further aggravated by heavy rainfall and deforestation. This integrated approach, combining bathymetric data with GIS technologies, improves our understanding of dam siltation in Morocco. The results provide valuable information for decision-makers and water resource managers, providing essential information for strategic planning and the implementation of measures to mitigate the impact of siltation.

The expansion of silting in the Algerian High Plains of south Oran (northwestern Algeria) is the ultimate manifestation of desertification. The presence, accumulation or deposition of sands in areas that previously did not contain any is the most visible sign of this silting up phenomenon that has begun to appear in recent decades. The present study focuses on the evolution and progression of silting up in the region under study. It is worth noting that assessing the narrowing of the vast endorheic depressions in this area is a very complicated task due to the vastness of the place. In order to deal with this problem in an efficient manner, it was deemed necessary to use remote sensing as it offers possibilities of global vision of the area to be studied and allows a precise description in time and space of this region. In order to efficiently identify and apprehend the phenomenon mentioned above, it was decided to adopt an analysis methodology that is based on the processing and interpretation of multi-date satellite images, combined with exogenous data. It should be noted that the topographic maps of Mecheria and Ain Sefra are given at a scale of 1/200,000 and are supplemented by some field data, along with some wind data. The analysis of data brought from different sources has made it possible to locate, characterize and map the evolution and the spatio-temporal dynamics of the recent extension of sandy accumulations, old Quaternary dune belts, and shrinking of vast endorheic depressions (Chott El Gharbi and Sebkhat Nâama). It is widely acknowledged that areas that are most affected by the progression of silting are the Plain of Naama, that is surrounded by the first Saharan Atlas ranges and by the orographic corridor formed by the double SW/NE alignment of Djebel (Mount) Morhad, Djebel Suigua, Djebel Aissa and Djebel Mekter located south of Ain Sefra. It is important to note that all this information, which is extracted from satellite images and exogenous data, will be integrated into a GIS. [ABSTRACT FROM AUTHOR]

Analysis of long-term data provides a valuable approach to determining the extent of biodiversity decline and likely causes, but such approaches are rare in large tropical rivers. We investigated the response of the fish fauna to hydrological, climate and anthropogenic factors over the period 1982–2017 in the lower Ganges (Padma) River, Bangladesh. Systematic effort-based sampling of fish between 2007 and 2017 from a 70-km reach showed a decreasing trend in abundance and diversity. Compared to 1982 data for the same sites and fishing methods, 28 fish species, including 16 nationally threatened ones, were absent in recent catches, suggesting local extinction of these. Fish community diversity was negatively affected by fishing pressure (71 fishermen in 1980, 2616 in 2019, 37.8-fold increase) and non-native species abundance (6.8-fold increase in abundance between 2007 and 2017). Permanent water area has reduced by ~ 50% since 1984. Annual mean rainfall, Ganges water depth and river discharge at the study location decreased significantly since 1980 (by 19.2%, 17.8% and 27.6% respectively, while annual air temperature increased (25.1 °C in 1981 to 26.2 °C in 2019). Water diversion at the Farakka Barrage, ~ 70 km upstream, is partially responsible for reductions in permanent water area in the study reach. Potential sources of biological invasion and water pollution have been identified. Widespread ecological consequences on fish diversity and productivity, resulting from multiple factors, are occurring in the lower Ganges. Reduction of fisheries impacts and improved prevention of accidental aquaculture releases of non-native fishes are identified as conservation priorities for arresting the decline of native fishes in the lower Ganges. [ABSTRACT FROM AUTHOR]

The formation of sandbars, spits and shoals are common at the inlet mouth particularly along coasts dominated by longshore sediment transport. These formations act as barriers, thus preventing the ingress of tidal flow. Sandbar and spit formation can be preferably averted by the construction of a pair of training walls, after which monitoring the behaviour of the stability of the tidal inlet is of prime importance. In cases where the tidal inlet meets a riverine estuary, the inlet dimensions and rate of littoral transport are primarily governed by the volume of water exchanged at the inlet mouth and the ebbing tidal currents, respectively. This paper discusses the case study of a micro-tidal inlet at Karaikal (10°54′52″N; 79°51′09″E), situated along the southeast coast of the Indian peninsula. This inlet coincides with the mouth of the Arasalar estuary, a tributary of the Cauvery river. A numerical model using the finite volume method is applied to estimate morphodynamic changes in the inlet channel driven by tide-induced currents and riverine discharge during the North-East monsoon season and the same has been validated through field measured data. The ultimate aim is to arrive at mitigation measures to combat siltation within the inlet. [ABSTRACT FROM AUTHOR]

In recent years, the resulting siltation from railway debris flow disasters has seriously affected the normal use of railway traffic lines and brought great challenges to rescue work. In view of this, we used an orthogonal test scheme to prepare different types of debris flow accumulation and carried out penetration resistance tests in order to explore the effects of different types of curing agents, the amount of curing agent added, the moisture content of debris flow siltation, and the grain gradation of debris flow sediment on the solidification strength of debris flow siltation. We also utilized scanning electron microscopy (SEM) to observe the microstructure and potential curing mechanism of the samples treated with different curing agents in attempt to discern the reasons for their different levels of strength. Our results show that the each of four curing agents tested can effectively improve the solidification strength of the siltation. Furthermore, we found that the type of curing agent had the largest impact on the curing strength of the siltation, followed by the moisture content of the siltation itself, the amount of curing agent added, and particle size. To achieve the best results, we recommend using 14% sulfoaluminate cement as the curing agent. [ABSTRACT FROM AUTHOR]

By collecting the sea gale, water depth and dredging daily report of Guoneng Huanghua Port channel from 2017 to2021, the seasonal distribution of strong wind and corresponding wind energy was calculated, and the temporal and spatial distribution characteristics of siltation in the channel in recent years and its correlation with wind energy were analyzed. The results show that the siltation volume of the channel in recent five years is 15 million m³ to 32 million m³, and the average siltation intensity of the whole channel in five years is 1.80 m, of which the maximum is 2.59 min 2018. The siltation outside the shield section is significantly greater than that inside the shield section. The strong siltation section is distributed near the entrance. Corresponding to W6+0-W24+0 section, the maximum siltation occurs in W9+0-W13+0 section, and the maximum annual siltation intensity is 7.83 m of W12+0 section in 2021. Channel siltation is mainly concentrated in spring and autumn, and the weakest in summer. In terms of time distribution, except for the influence of typhoon, it is consistent with the seasonal distribution of gale wind energy; gale is the main inducement of channel siltation, and there is a certain correlation between channel siltation and energy generated by gale. [ABSTRACT FROM AUTHOR]

The recovery of mud is the only way to solve the problem of silting up dams. At the beginning of the 1990s, we studied the recovery of mud from a dozen dams in construction and agricultural fields. In the case where the destination of the silt is known thanks to the chemical, physical and mineralogical analyses, the desiltation is carried out in a continuous way; in this case, we speak of sustainable desilting. This is what this paper discusses for the first time. Sustainable desilting consists of equipping the dam with one or more dredges that continuously remove silt. Once the mud is discharged and then stored in basins built upstream of the dam, the water returns to the reservoir. Once dried, the mud is transported to its place of use, but preferably in the agricultural field. [ABSTRACT FROM AUTHOR]

This paper seeks to determine the siltation level of the Lugu dam reservoir, Sokoto State, Nigeria, using the bathymetric survey method. A total of eleven (11) ground control points were established over the study area using Hi-Target Global Navigation Satellite (GNS) Real-time Kinematic (RTK) System. The base station was set- up over the reference Bench Mark while the Rover station was moved around to predetermine locations of the ground control points. The depths to the Lugu dam reservoir bed, as well as its underwater topographic mapping with a section of the River Rima on the right flank of the reservoir area, across the collapsed spillway were conducted using Garmin Global Positioning System Map. This was mounted on a nine feet fibre boat to enhance the echo sounding. The result of the study was used to produce a digital elevation model, topographic contours and the area-elevation-capacity curve for the reservoir. This indicates that between elevations 260.5 m and 262 m, the available minimum and maximum designed storage capacities of Lugu dam reservoir ranges from 21.24 MCM and 34.25 MCM respectively. The Lugu dam reservoir maximum storage capacity at breached level stands at 25 MCM, while its active storage capacity is 20 MCM. This is to conclude that the amount of siltation at the reservoir is 9.25 MCM representing 27.01% indicating the difference between the maximum designed capacity and the current storage capacity. It is recommended that dredging be carried out to regain the initial designed storage capacity as this will no doubt put an end to the incessant flooding and erosion experienced in the area.

Floods have a significant negative social, economic and environmental impact on both individuals and communities. The results of floods, both negative and positive, differ greatly depending on the placement and amount of flooding. Global data from a previous couple of decades shows that the number of displaced people by natural disasters is on the increase. In India, the North-Eastern region, especially Assam, is liable to natural disasters like earthquakes, floods, landslides, occasional droughts, etc. Among them, floods are the most common natural disaster that causes displacement every year in Assam. In this backdrop, the present study is an attempt to make an assessment of flood-induced displacement among the people residing in flood-prone areas of the Dhemaji Development Block, Dhemaji District, Assam. A total of 195 respondents were included in the study. The study mainly focuses on the reasons, types as well as problems faced by the displaced people in the Dhemaji District. Due to the effects of flooding, the majority (53.84%) of respondents were displaced from their usual place of residence. They were displaced mainly due to two reasons: silt deposition (13.84%) and soil erosion (28.20%) in their habitat. Among them, temporary displacement (35.89%) is very more common than that of permanent displacement(7.94%). [ABSTRACT FROM AUTHOR]