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Soils with Problems Due to Anthropogenic Reasons (Degraded Soils)
Published in Manorama K.C. Thampatti, Problem Soils, 2023
The off-site impacts of soil erosion by water are not always as apparent as the on-site effects. Eroded soil, deposited down slope, inhibits or delays the emergence of seeds, buries small seedlings and necessitates replanting in the affected areas. Sediment that reaches streams or watercourses can accelerate bank erosion, obstructs the natural water flow, get deposited in reservoirs, damage habitat of aquatic organisms and degrade downstream water quality. Pesticides and fertilizers, frequently transported along with the eroding soil, contaminate or pollute downstream water sources, wetlands and lakes.
Settling of tailings
Published in A.A. Balkema, Tailings and Mine Waste 2000, 2022
Economic effect of new technology for settling the tailings will be enormous. Settling plants may be located at concentration mills and form a common complex. The sediment obtained may be used as construction, road, and backfill material. The water and soluble reagents used for concentration of ores will be recycled.
Water Supply Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Sediment from construction sites is managed by installation of the following: Erosion controls such as mulching and hydroseeding with natural fiber geotextiles.Sediment controls such as sediment basins and silt fences.
Model studies for the design of inlet transition of settling basins of hydropower projects in high sediment yield areas: a review
Published in ISH Journal of Hydraulic Engineering, 2023
J. Chandrashekhar Iyer, E. J. James
In the case of run-of-river and small storage hydropower projects in a heavily sediment-laden river, wide variety of sediment management strategies need to be deployed to preserve the reservoir storage and also to minimize the entry of undesirable sediments into the settling basin. Morris (2020) has elaborately discussed about the strategies available to combat reservoir sedimentation which broadly is as under: Reducing sediment yield through watershed management (erosion control methods) and trapping of river sediments in the upstream through check dams, detention basins, etc.Managing flows during periods of high sediment yield to minimize trapping in reservoirs.Removing sediments already trapped in reservoirs using a variety of techniques.Adaptive structural and functional measures.
Magnitude–frequency analysis to assess effective discharge at daily and monthly timescales in South Indian River basins
Published in ISH Journal of Hydraulic Engineering, 2021
Shobhit Maheshwari, Sagar Rohidas Chavan
Sediment transport is mainly controlled by surface water flow within the river basins. It is responsible for reducing the carrying capacity of channel networks and storage capacity of reservoirs/dams. It is obvious that the floods are the main reason behind excessive transport of sediment loads (fine, medium as well as coarse sediments) through river networks. Research in the past has shown that the effectiveness of extremely large floods to carry greater quantity of sediment loads is less when compared with the effectiveness of smaller and more frequent floods. It was observed that the flood events which recur more than once per year account for 78–95% of the total suspended load (Wolman and Miller 1960). Various natural and anthropogenic changes in a river basin also result in considerable changes in sediment transfer mechanism within the basin. Overall, sediment transport affects the development and maintenance of channel network cross sections and the meanders movement. Excess sediment transport can also adversely affect the storage capacity of reservoirs/dams that reduces the availability of water in the reservoirs and quality of river water. Reservoirs of water control structures (e.g. dams, barrages) are considered as a main source of water in arid as well as semiarid areas and their sustainability is of huge importance for the society (De Araujo et al. 2006).
Hypolimnetic oxygenation 4. Effects on turbidity in Camanche Reservoir and its downstream fish hatchery
Published in Lake and Reservoir Management, 2020
Clear water is generally desirable for aquatic life, though some species thrive in muddy water characteristic of major rivers like the Mississippi River. Fish eggs in hatcheries or natural river gravels are especially at risk from suspended sediments since eggs can be smothered and killed. Concern about fish and turbid dam releases is warranted (Ward and Stanford 1995, Noh et al. 2014) because some reservoirs receive untrammeled stream inflows with turbidities as high as 150 NTU (Blaise and Hollabaugh 2006) and lower levels can also be detrimental (OWRB 2006). Dilution and settling occur once the stream flows into the reservoir, but effects can still be severe. Dense, cool, turbid flows to reservoirs dip at the plunge point and often flow along the bottom. Such turbidity plumes may exit via deep-water outlets used for power generation or to supply cool water to fish downstream. In shallow reservoirs, large areas may reach 35 NTU following storms (e.g., City of San Diego 2006) and wind stirring can increase turbidity in shallow water (Loveless et al. 2006). In contrast, drinking-water supply agencies using intakes at mid or upper levels of the hypolimnion generally find acceptable low turbidities of 0.5 to 1.5 NTU that approximate the USEPA drinking water standards of 0.3–1.0 NTU.