Siltation

About: Siltation is a research topic. Over the lifetime, 1420 publications have been published within this topic receiving 20983 citations.

Siltation of the reservoir of vea irrigation dam in the bongo district of the upper east region, ghana

Abstract: The Vea Irrigation Dam was constructed in 1980 to promote the production of food crops in the dry harmattan season. Thirty three years after construction, this study was conducted to assess the level of siltation in the reservoir and farming practices that impacts siltation within the catchment. Ten soil profiles, five on either banks of the reservoir and each of surface dimensions 1.2 m x 1.2 m were dug in the reservoir 30 m away from the water to ascertain the depth of soil sediments. Average depth of sediments was multiplied by the area of reservoir to obtain the volume of deposited sediments, from which annual depositions were estimated. Eighty (80) farmers in the four fringe communities within the catchment (Vea, Gowrie, Kunkua, and Kuyelingo) were purposively sampled and interviewed. At an average depth of 1.1 m, total deposit of about 140000 m 3 of sediments into the reservoir should be a cause for concern. Conventional tillage and continuous grazing, practiced by majority of farmers along the steep slope of the dam’s upstream have direct influence on erosion and hence siltation of the reservoir. High intensity rainfall with high kinetic energies, recorded in the months of June, July, August and September results in considerable level of detachment of the already erodible soil aggregates, which contributes to erosion and subsequent siltation of the reservoir. Whilst vegetative cover reduces direct impact of rain drops, these are scanty and scattered: exposing the bare soil to erosion. In order to save the dam and its reservoir from short lifespan as a result of massive siltation, soil conservation measures, and Best Agricultural Management Practices on watersheds are recommended to local farmers within the catchment area.

Transport patterns in the chap phya estuary

Abstract: Present day's society asks for ever larger engineering works to be carried out in estuaries. The developing techniques of dredging and construction allow for great interventions in the natural phenomena with often far reaching consequences. The whole intricate system of transports of water, salt and sediments may be drastically changed,affecting the existing quasi-static equilibria between sedimentation and erosion. For the planning of such works a thorough knowledge of the estuarme hydrology is indispensable. The port of Bangkok, the mam gateway for traffic into Thailand, is situated in the estuary of the Chao Phya river (figure 1). Increasing navigation demands improvement of the harbour and its 55 km long approach channel but the interests of agriculture and municipal water supply must also be taken into account. The Netherlands Engineering Consultants (NEDECO) m combination with the Delft Hydraulics Laboratory have made a four-years study of the estuary covering a field survey and a hydraulic model test. The observations in nature served to obtain insight into the estuarme transport pattern m relation with the boundary conditions given by the regimen of the river and the state of the sea. The small scale tests gave indications of the changes in these phenomena to be expected from alterations of the situation m the estuary and of the discharge characteristics of the river. The field survey was carried out from 1961 to 1965 with four fully equipped survey vessels to measure current velocities (60,000 times) to take samples of water and sediments, to measure wave heights and for echo-soundings. In a laboratory the samples of water (70,000) and sediments were tested as to silt concentration, salinity and soil-mechanical properties. Together with meteorological, oceanographical and hydrological data from cooperating local authorities a picture was obtained of the phenomena in the estuary and the causes of the siltation m the dredged channel.

Dams Siltation and Soil Erosion in the Souss–Massa River Basin

Abstract: Siltation of 26 large and small dams, spatially distributed in the Souss–Massa basin, has been investigated The disparity observed in the reservoir’s silting reflects the variability of each watershed’s physical parameters that control the water erosion These parameters include in particular lithology, topography, climate, vegetation, hydrology, and human actions

Integrated Evaluation of Soil Erosion Hazard and Risk Management in the Oued Beht Watershed Using Remote Sensing and GIS Techniques: Impacts on El Kansra Dam Siltation (Morocco)

Abstract: The initial state of the Oued Beht watershed (430,728 ha) is characterized by a socio-ecological vulnerability associated to the water erosion risk. Especially, the consequences are chained and the soil loss alters its hydrological behavior and its ability to protect functional and structural challenges (good land, El Kansra dam, agricultural activities). In this perspective, this study suggests a methodology, reproducible and generalizable, to assess the natural water erosion risk (R). The approach used is based on spatial processing technology of information to develop a spatial database and geographic information system (GIS) concerning biophysical and topoclimatic parameters in the Oued Beht watershed. Thus, the risk analysis is obtained by combining thematic maps of Susceptibility (S) and potential Consequences (C). Although, the spatial analysis of maps obtained reveals the extent of susceptibility involving land degradation, with the potential risks, which generated a decrease in the storage capacity of El Kansra dam (?3.03 Mm3/year). The results show that erosion is active on more than three quarters (3/4) of the watershed, and a considerable loss of land with 8.36 Million tonnes per year. In this way, flood analysis and study of hydrometeorological events identified the vulnerability of flood sites (hot-spot) contributing at 77% of El Kansra siltation dam. Therefore, the consequence assessment is obtained by identifying risk elements and estimating potential damage coefficient, which represents the financial gap flow affecting the socio-economic context due to the erosion impacts.