Siltation

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

Tidal transport of mud/sand mixtures - laboratory tests

Abstract: An understanding of sediment transport in estuaries is important to enable greater control of processes such as siltation, dredging, and possible pollution. The bottom sediment contained in estuaries is generally a mud and sand mixture, and it is this mixture which is entrained into the water column during periods of higher flow and redeposited during slack flow conditions. This report covers laboratory tests performed on a wider range of mixed mud and sand beds. It extends previous work to include wave erosion tests and erosion tests on undisturbed samples.

Anthropogenic effect on deposition dynamics of lake sediments based on 137Cs and 210Pbex techniques in Jiuzhaigou National Nature Reserve, China

Abstract: Radionuclide dating techniques characterized by 137Cs and 210Pbex have recently been applied in the study of lake sediments around the world. In this study, a chronological series of sediment cores was established based on 137Cs and 210Pbex analyses along with the evaluation of sediment properties, such as particle size distribution, total organic carbon (TOC), carbonate content, and acid-insoluble residue, to study sediment accumulation rates, sediment sources, and responses to human activities in the Jiuzhaigou National Nature Reserve in southwestern China. In terms of the particle size distribution of sediments, silt content was the highest, and clay and sand contents were relatively low. The sediments displayed high TOC contents because of the significant amounts of vegetation grown in the lakes. The carbonate content was also high due to the overall geological background of carbonates in Jiuzhaigou. Carbonate content tended to decline from top to bottom in the sediment cores, whereas the acid-insoluble residue tended to increase. These results suggested that the depth variation of the environmental parameters of the sediments in two lakes in Jiuzhaigou would correspond to each other. The results indicated that the sediment rate of Jiuzhaigou was generally high with strong siltation, indicating that serious soil loss was induced by intensive human activities in the basin over the past decades. The increases in the mass accumulation rate, contents of acid-insoluble residue, and mean particle size during the periods of 1840–1900s, late 1930s-early 1950s, 1966–1978, and 2003–2006 revealed the occurrence of severe soil and water loss as a result of extensive agricultural expansion, large-scale deforestation, and road construction in Jiuzhaigou. The deposition rate and the properties of lacustrine sediments could reflect the significant impact of human activities on lake sedimentation during Jiuzhaigou’s history.

Environmental impact of mining, erosion and sedimentation in Sri Lanka

Abstract: Erosion and sedimentation have a devastating effect on the environment of Sri Lanka. The Central Highlands with very steep slopes and a radial network of rivers that begin in these mountainous regions cause major erosional hazards, often resulting in disastrous landslides. Mining, particularly gem mining, has been responsible for serious problems of soil erosion and river siltation. A large number of illegal mines leave mine spoils resulting in damage to nearby paddy fields, crops, rivers and streams. Extensive sand mining in some rivers has lead to the collapse of river banks, destabilising structures such as bridges and causing influx of salt water. Landslides and coastal erosion are other factors that have had a negative impact on the environment in Sri Lanka.

Sediment yields in the Exe Basin: a longer-term perspective

Abstract: In the UK, fine sediment is viewed increasingly as a diffuse pollutant due to its role as a vector for the transport of potential contaminants, and in causing siltation, which may have adverse effects on river and estuarine habitats. There is a need, therefore, for river managers to have reliable information on sediment budgets in order to plan measures that will achieve good status under the EU Water Framework Directive. As part of a wider sediment-budget investigation in the EU-funded Cycleau Project, detailed records of fine sediment yield over the 10-year period from 1994-2003 have been analysed for the Exe Basin (1500 km 2 ), a principal river system of southwest England. The longer-term average yields in the three major tributaries of the Exe Basin are discussed and results of monitoring of sediment loads at a site near the tidal limit over a one-year period confirm the importance of the River Exe in contributing sediment to the Estuary.

Bottom topography, recent sedimentation and water volume of the Cerro Prieto Dam, NE Mexico

Abstract: The Cerro Prieto dam, a relatively small water reservoir in NE Mexico, is one of the main resources of potable water for Monterrey, a city with a population of about four million inhabitants. A high resolution seismic study using non-linear parametric sub-bottom echo-sounder SES-2000 was carried out in this water reservoir. High resolution acoustic data interpretation shows that the thickness of recent sediments due to siltation of the reservoir reaches 3.5-4.0 m. It shows a high recent sedimentation rate (1-2 up to 14 cm/ year). Based on the echo-sounder data, the first bathymetric map and a digital model of recent sediment thickness were designed. A significant (5-12%) difference between the volume capacity value used by National Commission of Water (CNA) and acoustic survey results was revealed. Differences between the CNA and acoustic data indicate storage losses from 12-17 up to 30 million cubic meters. The results obtained through study such as this one, could be useful to improve a water resources management.