Siltation

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

A Story of the Wetland Water Quality Deterioration: Salinization, Pollution, Eutrophication and Siltation

Abstract: Water quality has historically relied upon wetland openness and water availability. For many years until 1986, Las Tablas de Daimiel wetland was enabled to export water and materials downstream, thus diminishing the impairing effects of pollutant storage. Since 1987, when the wetland was dammed, good-quality inputs of low-salinity groundwater were discontinued, streams directed urban and agricultural wastewater towards the wetland, discharge inputs were rather low, due to groundwater exhaustion in the catchment and, hence, its internal loading had greatly increased. As a result, wetland salinization, pollution and eutrophication increased both in water and sediments, and siltation appeared as a severe threat. This chapter will review long-term patterns (1945–2007) of these processes, paying special attention to wetland connectivity and water export downstream.

Identification of seasonal variation of water turbidity using NDTI method in Panchet Hill Dam, India

Abstract: Sedimentation in reservoir is a common problem in any multipurpose river valley project and is effective upon the performance of it. Every dam has an estimated volume of water holding capacity at the time of inception, but it gradually reduces by siltation. The presence of sediments in water causes turbidity and it slowly precipitates on the floor of the reservoir. Normalized difference turbidity index (NDTI) is a remote sensing technique widely used to identify the water turbidity, which is the ratio of red and green bands of solar spectrum. In Panchet Dam actual rate of siltation exceeds the assumed rate that fills up the entire reservoir area at a faster rate. In this situation, the study has been conducted to explain the variation of water turbidity of the dam throughout the year 2015. Major findings of the study indicate that the turbidity level jumps from 60 NTU to 700 NTU in the monsoon. High turbid water covers 50.57%, 64.22% and 52.79% area of the reservoir in July, August and September, respectively. In contrast, coverage of low turbid water is more than 71.68% in the months of February and June. The medium turbid water covers less than 35.82% area throughout the year except the months of September and October. High level of correlation exists (R2 = 0.900) between NDTI values and total suspended sediments concentration in mg/L (N = 15, p < 0.05) with minimal RMSE (13.59). Variation of seasonal turbidity and different types of turbidity are significant at 95% (p < 0.05) level of significance. The paper is an attempt to probe into the seasonal variation of water turbidity of the dam with the application of NDTI method and related statistical measures.

Simulation of sedimentary dynamics in a small-scale estuary: the role of human activities

Abstract: Human activities, such as tidal sluice gate construction and reclamation, are prevalent along northern coastline of China and influence significantly sedimentary environments. The Sheyang River estuary is a small estuary situated on the Jiangsu coast. For the objective of storing fresh water, maintaining river channel depth and managing the land resource, a tidal sluice gate was constructed. At the same time, estuarine wetlands have been reclaimed extremely in recent decades. A numerical model based upon Delft3D was developed to quantify the impact of these human activities, and four simulation schemes were designed (a) tidal sluice gate present, but always closed; (b) tidal sluice gate not present; (c) tidal sluice gate present, but closed during flood and open during the ebb; and (d) intertidal area reclamation taking place in the estuary. A bathymetric survey confirmed the erosion and deposition results of the simulation. The rate of sediment deposition increased significantly after the gate was closed. However, during the third scheme, the sediment deposition rate reduced considerably; that was because the ebb current increased the scouring force when the gate was open, especially within the channel area close to the gate. Meanwhile, reclamation lessened erosion behind the gates and may have been enhanced by siltation. The coastline shifted seaward as the siltation area increased; it extended farther because of reclamation. Appropriate coastal management planning strategies must be developed to reduce negative effects of the channel siltation, resulting from the various forms of human activity. The results of this study can provide input to governmental recommendations on more effective tidal gate management strategies.