Water systems contain fine sediment as a natural phenomenon. The main cause of ecological deterioration is undesirable fine sediment. Fine sediment comprises inorganic particles of sand, silt, and clay that are less than 2 mm in diameter. Fine sediment is considered to be pollutant in water bodies (rivers, streams, lakes, and reservoirs). Sediment has various channel and nonchannel sources. Fine sediment can alter the hydraulics of rivers and their morphology. It has detrimental effects on reservoir storage and function, can degrade the food chain, and affects the reproduction of aquatic animals, which ultimately affects river ecosystems. The deposition of fine sediment renders waterways difficult to navigate and hinders recreational uses. It degrades the water quality for drinking purposes, wildlife, and affects the land surrounding the bodies of water. The intrusion of fine sediment is a global problem, and with time, researchers will understand the effects on biological and physical processes. Comprehension may help scientists minimize the effects of fine sediment on river ecosystems by considering various disciplines such as ecology, hydraulics, fluvial geomorphology, and hydrochemistry. Many researchers have investigated fine sediment in rivers. This paper reviews the literature, focusing on the consequences of intrusion on the river ecosystem, river health, and associated hydraulic parameters. The study of FSI is a major application in applied environmental science. It is applied to gain as complete an understanding of the physical and biological processes as possible. It has been applied to estimate the trap efficiency and to determine the live storage capacity of reservoirs. Excess fine sediment is a primary reason for the failure of water bodies, so it is important to control it and maintain necessary fluid properties such as viscosity, specific weight, and the optical properties of water. Proper control of fine sediment in bodies of water maintains both the survival and growth of plants, and the food chain of aquatic animals. It is important to control excess fine sediment to avoid turbidity in water. In brief, the topic has applications in various fields such as evaluating river health, live reservoir capacity, growth of flora and fauna, and water quality standards.

Scour is a natural phenomenon in rivers caused by the erosive action of the flowing water on the bed and banks. Spur dikes are constructed across the flow to protect the bank from erosion by shifting of the river away from the bank. The spur dike undermines due to river-bed erosion and scouring, which is generally recognized as the main cause of spur dike failure. In this study, accuracy of existing equations for the computation of maximum scour depth has been checked with available data in the literature and data collected in the present study using graphical and statistical performance indices. Three new relationships are also proposed to estimate the maximum scour depth and maximum scour length upstream and downstream of spur dike. This new relationship for maximum scour depth is shown to perform better than other existing equations.

Scour is a natural process in rivers initiated by the erosive action of the activated water. Spur dikes are built across the flow to defend the stream erosion and facilitate the shifting of the river away from the bank. The spur dike weakens due to stream bed scouring and erosion, which is usually documented as the key reason of spur dike failure. Failure of spur dikes due to local scour has inspired many investigators to discover the cause of scouring phenomenon and to forecast the temporal and maximum scour depth near spur dikes. In this paper, a review of the scour around spur dikes with all possible aspects, like temporal and maximum scour depth, flow pattern, parameters affecting scour phenomenon has been discussed briefly.

Div style="box-sizing: border-box; color: #333333; font-family: 'Open Sans', sans-serif; font-size: 17.6px;"> Computational Fluid Dynamics (CFD) represents a useful tool to study natural currents in the rivers and estuaries with erosive materials; therefore, it is always in the keen interest for scientists to further study and advance it, especially when numerical model has the advantages compared to actual laboratory experiment in terms of cost, time, and restrictions on conditions of the physical models and field collections. The present study deals with the hydro-morphological investigation and numerical modeling of a group of vertically stationed parallel groynes using FLOW-3D commercial software. To validate the results of the FLOW-3D simulation, it has been compared to the experiments from literature. Besides, a SSIIM 2.0 software has also been employed to compare with some of the FLOW-3D results. It was found that the accuracy of the FLOW-3D model influenced by the approach Froude number and the critical velocity ratio (Uavg/Ucr). Even though it underestimated the measured scour depth (due to complex and intense vortices, which reduce the accuracy of the numerical models), but general results from the model have reproduced the measured data well.