Siltation

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

Influence of check dams on flood hydrology across varying stages of their lifespan in a highly erodible Catchment, Loess Plateau of China

Abstract: Check dams are applied worldwide as an effective approach for soil conservation. Its effect on hydrology, however, has not been fully understood. As a critical step towards revealing the lumped effect of check dams at the regional scale, this study explored the modified flood hydrology induced by check dams in a representative highly erodible catchment in the Loess Plateau, China. A coupled hydrological and hydraulic modeling approach was applied to simulate the flooding process in different stages of deposition and topographic changes in a check dam reservoir. The results suggest a paradigm shift of the dam effect on flood attributes, which transits from a total interception in the early stage of the dam to peak reduction and flood detention, rather than a complete loss of flood control functions, when it approaches the maximum capacity of sedimentation. Under the same level of deposition, the reduction of a minor flood by a check dam was higher than that of a major flood. The topographic changes contributed to the reduction of flood peak appreciably by reducing the flow velocity and retarding the flood propagation. Noticeably, this reduction was augmented with the advancement of siltation and topographic changes, indicating the persistence of the hydrologic effects of check dams in the long run. As a result of these hydrological changes, the reduction in the flood flow velocity induced by check dams suggests substantial reductions in sediment transport and channel erosion during floods. In addition, a dam system containing multiple, cascading check dams exhibits much more significant effect in modifying both hydrologic and hydraulic properties of flood than individual dams. The current research provides a mechanistic understanding of the effects of check dams on catchment hydrology under heavy rainstorm conditions in small catchments.

Depositional environment and silting in the Sharavati estuary, central west coast of India

Abstract: Variation in textural characters (silt sand ratio, mean size, sorting and skeweness) of the Sharavati estuarine sediments has been studied to understand their depositional environment. Seventeen locations within the estuary and two locations just at the entrance of the sea were selected for the study. During September 2000, medium grained (1.36-1.86φ), well sorted to moderately well sorted sediments were observed in the estuary, whereas they were fine grained (2.67-3.φ) and poorly sorted in the entrance of the sea (0.84). The estuarine sediments were relatively fine-grained during December 2000 (postmonsoon) (1.3-2.18φ) and February 2001(premonsoon) (1.15-2.3φ) as compared to the monsoon season. The siltation in the estuary is mainly due to offshore source brought by tidal currents followed by mixing of saline and fresh water in the estuary.

Sediment transport trends in Lianyungang coastal waters

Abstract: On the basis of the grain size analysis of surface sediment samples collected from Lianyungang coastal waters in winter and summer respectively,sediment transport trends are studied using the method of Gisedtrend,and influence factors are also discussed.The results show that the sediment transport trends in Lianyungang coastal waters are obvious.The sediment transport trends in the Haizhou Bay are southwest ward,which is consistent with the silting on the top of the bay.The sediment transport trends south of the port area are convergent.A characteristic distance,a sampling grid,a surrounding environment,and grain size fractions have a direct effect on a grain size trend analysis.Taking into account the influence of coastline,island,artificial boundary as well as the grain size fractions can enhance the reasonability of the grain size trend analysis.

Basic Characteristics of Sediment Transport in Hangzhou Bay

Abstract: Entering such a funnel-shaped Hang zhou Bay, the actions of both tide and tidal current are strong.The Bay is connected with the Yangtse Estuary whose annual sediment discharge of 480×10~7 tons is carried ocenaward, and, through analysising the temporal and spacial distri-butions of suspended sediment and bottom sediment,the sediments of the Bay come mainly from the Yangtse Estuary. Sediments exchange between the Yangtse Estuary and the north-bank of Hangzhou Bay can also be analysed from salinity, tide, tidal currents and residual currents.Sediments of the Yangtes Estuary diffuse toward the south through the mouth of Hangzhou Bay when sediments is carrieda in or out of the Bay, and under the flood and ebb currents from the east and the west, its total amount may reach 1×10~9 tons per day.So, this sediments exchande is enormous, but the amount of sediment carried in or out of the Bay is relatively small, only 4×10~6 to 11×10~6 to tons per day.Thus,in general, there seems a rough balance exists between erosion and siltation in the Hangzhou Bay.However, the local change with erosion and siltation in the Bay is adjusted by the sediments′longshore transport.

Coastal erosion and its environmental effect in the Modern Yellow River Delta

Abstract: The coast of Modern Yellow River Delta belongs to silt muddy coast,and it is impacted together by the volume of water and sand of Yellow River and marine coastal hydropower,its erosion is serious and the change has obvious temporal and spatial characteristicIn 1976,the Yellow River changed its flow along Qingshuigou,the coast of Diaokou outfall,which is the old course of Yellow River,began to erodeAt the early years,the velocity of erosion is fast,recent ten years,the velocity is slower obviouslyTo the contrary,in the current outfall area occurs silting upSince 1990s,especially recent years,the sediment discharge in the Yellow River was becoming less and less,so the area of siltation is limited around of current course,and the erosion occurs at large area in coastAs a typical coastal wetland of China,the environment of Modern Yellow River Delta is degraded because of the erosionWe should systematically and roundly research the complexity of coastal erosion in order to establish an integrated management system to mitigate it and improve the environment of coastal wetland