Siltation

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

Onshore Transport of Shelf Sediments into the Netravati-Gurpur Estuary, West Coast of India: Geochemical Evidence and Implications

Abstract: Surface accumulation of a long band of frothy material is frequently noticed in the Netravati-Gurpur and other estuaries along the central west coast of India. This is prominently seen in the flood phase of the tidal cycle, during summer. In order to understand its source and the process of formation, water samples along with frothy material were collected from the Netravati-Gurpur estuarine front during the summer of 1987. Also collected were riverine and estuarine-coastal suspended particulates and surficial sediments from the adjoining inner shelf. Salinity of water samples was measured and the remaining samples were subjected to bulk and partition geochemical analyses. Suspended particulate matter (SPM) concentrations in the estuarine front in the flood tide during summer (February-May) is anomalously higher (4,310 mg/l) than in riverine (51 mg/l) and estuarine-coastal (11 mg/l) waters during monsoon (June-September) and post-monsoon (October-January) seasons, respectively. The frothy material is composed chiefly of fine particles (< 63 microns) with a minor proportion of shells (foraminifers, ostracods and gastropods) and plant debris in the coarse fraction. Geochemically, the frothy material is similar to the Netravati-Gurpur SPM, but has low Al (13.87%), high organic matter (22.62%) and an order of magnitude higher Ca content (2.91 %). All these lines of evidence suggest that the frothy material is detrital and that it is derived from the marine environment by resuspension and landward transport of bottom sediments during the flood phase of the tidal cycle. This inference is in agreement with similar reports from many parts of the west coast of lndia. Implications of this process are discussed in terms of siltation in the navigational channel of the Old Mangalore Port, estuarine morphology and disposal of effluents from the existing and proposed industries along the west coast of India.

Effects of Land Deals on Peak Discharge and Sediment Transport in the Catchments Around the Grand Ethiopian Renaissance Dam

Abstract: Land degradation poses a threat to reservoirs because of siltation; hence, sustainable hydropower development necessitates the conservation of upstream catchments Ethiopia is currently constructing Africa's largest hydropower dam, the Grand Ethiopian Renaissance Dam (GERD), on the Blue Nile Given the commercialization of large tracts of land in the closer catchments, there is a need to explore the effects on peak discharge and suspended sediment concentration A field survey was conducted on 20 ephemeral streams to compare annual maximum peak discharges between catchments (0·4 – 15·5 km2), eight of which drain commercial farms and twelve others, land under traditional management We measured channel characteristics, observed flood marks and applied the empirical Manning equation to calculate peak discharges SSC samples were taken during each runoff event from a stream in each of the two dominant land management categories Results indicated that commercial farms contributed for the 51% increase in peak runoff compared to traditionally managed lands Catchments dominated by commercial farms also have a significantly higher SSC (mean = 6·44 ± 2·23 g l−1) compared to catchments without commercial farms (mean = 2·77 ± 2·31 g l−1) Forests and woodlands have a strong buffering effect upon flood generation while higher peak discharges and sediment transport have generated from crop lands However, leasing forests and woodland to agricultural companies has resulted in deforestation Consequently, the increased runoff response may lead to downstream bank erosion and affect downstream communities; the increased sediment transport poses a threat to the multibillion dollar hydropower reservoir of the GERD Copyright © 2016 John Wiley & Sons, Ltd

Mapping and accuracy assessment of siltation of recharge dams using remote sensing technique.

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

UTILIZAÇÃO DO SIG NA DELIMITAÇÃO DAS ÁREAS DE PRESERVAÇÃO PERMANENTE (APP's) NA BACIA DO RIO SAGRADO (MORRETES/PR) Use of Gis in the Delimitation of Mandatory Preservation Areas in the Hydrographic Basin of Sagrado River (Morretes/PR)

Abstract: This paper fi ts within the CAD program (Contaminants, Siltation and Dredging in the estuary of Paranagua/PR) purposing the application of GIS (Geographic Information System) in delimitation