Siltation

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

Dredging Effects on Eelgrass (Zostera marina) in a New England Small Boat Harbor

Abstract: While speculation on effects of dredging on seagrass beds is plentiful, actual empirical data documenting these effects are not. In this study, acoustic-based seagrass mapping techniques were used to generate detailed maps of seagrass distribution before and after dredging operations. Eelgrass (Zostera marina) within Scituate Harbor, MA, was monitored during mid-summer in 2001, 2003, and 2004; navigation maintenance dredging of the harbor was performed during fall 2002. Similar surveys were also performed during the same timeframe at an un-dredged harbor near Wood Island, Maine. Two types of potential impacts were examined. Direct impacts involved physical removal of vegetation along with the dredged sediments. Indirect impacts in adjacent undredged areas may occur as a result of increased turbidity and/or siltation associated with dredging activities. Using hydroacoustic techniques, we were able to easily map and quantify direct impacts to eelgrass resources. Assessment of indirect impacts, however, was more complex. In the first post-dredging survey, a substantial reduction in coverage occurred in adjoining un-dredged areas, suggesting possible indirect impacts. This was followed by a modest recovery between the first and second post-dredging years. However, monitoring of other un-dredged sites within the region showed natural year-to-year variations in eelgrass coverage to be almost as large as those occurring at the dredged site. Results emphasize the need for long-term data to discern any potential effects of dredging on seagrass dynamics as opposed to a host of other factors contributing to high variability in measured parameters.

Siltation and water level monitor

Abstract: The utility model relates to a siltation and water level monitor belongs to the water conservancy industry automatic monitoring technical field that silts up under water Technical scheme: siltation and water level monitor contains monitoring host computer (6) and siltation and level sensor (8), and siltation and level sensor are rectangular form, along length direction distribution a plurality of electrodes (7) Long banding siltation and level sensor's length direction arranges perpendicularly downwards, measures the capacitance value of every electrode, it is different according to each electrode capacitance value to and the interval between each electrode, reach siltation thickness in real time The utility model discloses can monitor water level and siltation simultaneously, monitoring simultaneously is submarine again to monitor the surface of water promptly, can be long -time need not the thickness of artificial intervention's monitoring silt, the height of water level, in the deposit law of analysis silt, the situation of change of water level to and calculating storage capacity or discharge The utility model discloses the accuracy is high, the real -time is strong, it is simple to lay, the later maintenance volume is little

Analysis of reasons for the siltation in North Passage of Yangtze Estuary

Abstract: In view of the characteristics that siltation in the deep waterway of North Passage has been increased and converged mainly on the middle reach since 2005,we analyze systematically the impacts from the change of various factors such as sediment and hydrodynamics,find out the major reason for the increase of back-siltation amount on the middle reach,and put forward an idea for working out the siltation-reduction measures.

Morphodynamic evolution of the Xiaoqing River mouth: a Huanghe River-derived mixed energy estuary

Abstract: In an estuary, tidal, wave and other marine powers interact with the coast in different ways and affect estuary morphology as well as its evolution In the Huanghe (Yellow) River estuaries and nearby delta, there are many small sediment-affected estuaries with a unique morphology, such as the Xiaoqing River estuary In this study, we investigated the special evolution and genetic mechanism of the Xiaoqing River estuary by analyzing graphic and image data with a numerical simulation method The results show that NE and NE-E tide waves are the main driving force for sandbar formation Sediment shoals have originated from huge amounts of sediment from the Huanghe River, with consequent deposition at the Xiaoqing River mouth The lateral suspended sediments beyond the river mouth move landward Siltation takes place on the northern shoreline near the river mouth whereas erosion occurs in the south The deposits come mainly from scouring of the shallow seabed on the northern side of the estuary Storm surges speed up deposition in the estuary Development of the sediment shoals has occurred in two steps involving the processes of growth and further southward extension Although the southward shift increases the river curvature and length, the general eastward orientation of the estuary is unlikely to change Processes on the adjacent shorelines do not affect the development of the sediment shoals The study presents a morphodynamic evolutionary model for the Xiaoqing River estuary, with a long-term series cycle, within which a relatively short cycle occurs

Hydrological Response Unit Analysis Using AVSWAT 2000 for Keuliling Reservoir Watershed, Aceh Province, Indonesia

Abstract: Sediments deposition derived from the erosion in upstream areas can lead to river siltation or canals downstream irrigation. According to the complexity of erosion problem at Keuliling reservoir, it is essential that topography, hydrology, soil type and land use to be analyzed comprehensively. Software used to analyze is AVSWAT 2000 (Arc View Soil and Water Assessment Tools-2000), one of the additional tool of ArcView program. The results obtained are the watershed delineation map, soil type map to produce soil erodibility factor (K) which indicates the resistance of soil particles toward exfoliation, land use map to produce crop management factor (C) and soil conservation and its management factors (P). Hydrology analysis includes soil type, land use and utility for the erosion rate analysis through Hydrologic Response Unit (HRU). The biggest HRU value of sub-basin is on area 5 and the lowest one is on area 10. All four HRU in sub-basin area 5 are potentially donating high value for HRU. In short, this area has the longest slope length so that it has a large LS factor. About 50% of the land was covered by bushes which gain higher C factor rather than forest. Moreover, it has contour crop conservation technique with 9-20 % declivity resulting in having dominant factor of P. Soil type is dominated by Meucampli Formation which has soil erodibility factor with high level of vulnerable toward the rainfall kinetic energy. All in all, the vast majority of HRU parameters in this sub-basin area obtain the highest HRU value. Hydrology analysis, soil type, and use-land are useful for land area analysis that is susceptible to erosion which was identified through Hydrologic Response Unit (HRU) using GIS. As the matter of fact, spatially studies constructed with GIS can facilitate the agency to determine critical areas which are needed to be aware or fully rehabilitated.