Siltation

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

Modeling and Mapping of Soil Water Erosion Risks in the Srou Basin (Middle Atlas, Morocco) Using the EPM Model, GIS and Magnetic Susceptibility

Abstract: Abstract The Oued Srou watershed located in the Middle Atlas Mountain of Morocco has been a subject of serious soil erosion problems due to the combination of natural factors and anthropic activities. Therefore, soil erosion hazard assessment and mapping can be handy to initiate remedial measures in the area. In this study, the improved Erosion Potential Model (EPM) integrated with GIS and remote sensing techniques is employed to map and assess the vulnerability of the Oued Srou watershed to the water erosion phenomenon and its impact on the silting of the Ahmed El Hansali dam. The results of the EPM model showed that the maximum annual soil loss rates were in the range of 5-652 m3/km2/year, with an average of 49 m3/km2/year. The delivery coefficient ratio showed that about 34433 t/year of the sediments reach the outlet of the watershed. The correlation analysis between all erosion factors revealed the following order of their importance in the water erosion control: soil sensitivity to erosion, soil protection, slope, erosive state, temperature, and rainfall. The magnetic susceptibility provided results on the evolution of soils; it showed that the most degraded soils had a high erosion rate. Generally, the stable soils not eroded showed an upward increase of magnetic susceptibility values in soil profiles; the evolution of magnetic susceptibility of degraded soils is disturbed. The magnetic susceptibility has also made it possible to highlight the source zones of sediments that reach the outlet of the watershed.

Siltation mechanisms of Huanghua Port and 3D characteristics of nearshore suspended sediment concentration under waves

Abstract: Careful analysis shows that for wave dominate climate,the suspended sediment concentration is controlled by waves and showed large vertical gradients.The high deposition rates in the access channel of Huanghua Port is caused by high waves in storm events.Remote sensing and 2D horizontal numerical modeling need to be used with caution due to their lack of vertical resolution.It is recommended to apply field measurements and 3D numerical modeling whenever possible.

Method for controlling lake plant siltation by white rot fungi

Abstract: The invention aims at solving the problem of siltation promotion and accumulation of grass-type lake plant and provides grass restraining and siltation controlling technology and method which utilize microorganism in-situ remediation to speed up decomposition of bottom-mud plant residues. White rot fungicide is used for controlling siltation of lake plant and biological decomposition of lake bottom mud is sped up by lignin degradation. The method is used for controlling biofouling of lake aquatic plants by the means of microorganism, thereby having strong operability and wide application. The method avoids secondary pollution and has important effects on ecological restoration of lake ecosystem.

A brief analysis of scour and silting of the tidal flats at the north bank of the Hangzhouwan Bay

Abstract: The estuarine bank is located at the transitional area between the river and sea,where the interaction of 4 spheres takes place and various interfaces meetThe coastal bank at the forefront of the estuary is the most sensitive zone of land-sea interaction and also the important land resource for the big cities in delta areaBeach scouring and silting is a kind of natural phenomena in estuary,the study of which is of great theoretical and practical significanceThe north bank of the Hangzhouwan Bay is at the south edge of the Changjiang River deltaWith the increasing need of the land resources,this area has got more and more attentionsMany scholars have studied this area and got a lot of valuable resultsHowever,in the past tens of years this area has experienced significant changes and many issues need to be studied in depthBased on the digitalized process of 4 maritime charts(1976,1993,1997,2004) with ARCGIS software,scouring and silting of the tidal flats at the north bank of the Hangzhouwan Bay is studiedThe results show that:(1) the Hangzhouwan Bay was scoured at the northern bank and silted at the south bank in the history,while the north bank has experienced scouring first and then silting;(2) because of inning at the northern bank,the shoreline has moved outward in the past 30 years;(3) in the past 30 the Nanhui section was mostly in siltation state before 1997 and in erosion state after 1997;the Jinshan section was mostly in steady state;the section from Jinshanzui to Jinshanwei was mostly in steady state;the section from Caojin to Jinshanzui experienced a process from erosion to siltation and then to erosion again;and the Fengxian section was in erosion state,but the erosion zone moved from the east to the west and also to the north in 1997~2004,the erosion moved from the tidal flat below-5 m to the tidal flat above-5 mThe erosion and siltation at the northern bank of the Hangzhouwan Bay is affected by many factorsBesides tide and storm,inning and the decrease of sand from the Changjiang River is two important factors resulting in the scouring of the bank

Depositional Environments and Sediments in the Coastal Zone of Prince Edward Island, Canada

Abstract: Prince Edward Island has an area of 5700 km 2 , with a length of approximately 217 km and an average width of 27 km. Numerous coastal indentations account for a total coastline of over 1,770 km. Shallow bays and estuaries cut deeply into the landmass and nearly dissect it in several places. Man has established his major communities, industries, and recreational activities along the coastline and is being drawn there in increasing numbers, thereby placing undue pressure on the very environmental qualities which formed the original attraction. The estuaries produce large quantities of organic materials, and act as sediment traps and reservoirs for nutrients and chemicals. The processes of trapping, concentrating, producing and recycling sediments are of first order importance. Sediments in the estuaries and lagoons range from clay to coarse sand and gravel. They are contributed by marginal, internal and external sources. Sediment accumulation averages 0.4 cm/year. Fluvial waters transport and contribute the majority of the sediments to these environments. Tidal flow contributes to the resuspension and redistribution of river-borne sediments. Agglomeration, flocculation and deflocculation occurring in these estuaries have important affects on siltation and pollutant concentration. Organic constituents in the sediments are derived from pelagic, epi- and infaunas. The inorganic constituents are derived from a variety of sources. Concentrations of suspended particulate matter decrease from about 180 mg/l in upper estuaries to less than 3 mg/l in the lower estuary-lagoon complex. The organic matter content is highest (-3 to 5%) in fine-grained sediments. Heavy metals such as Cu, Pb and Zn are strongly associated with organic matter. River flow and the flood and ebb of tidal currents are the most obvious water motions in these environments. However, strong winds cause turbulence in shallow (< 5 m) waters. This turbulence initiates resuspension of previously deposited organic and inorganic materials. Depending upon the relative directions of wind and tide, winds may cause an increase or decrease in surface current velocities.