What happens if a reservoir silts in

J Geophys Res C10 Cont Shelf Res 22 11—13 — J Hydraul Eng — Roberts W, Le Hir P, Whitehouse RJS Investigation using simple mathematical models of the effect of tidal currents and waves on the profile shape of intertidal mudflats. J Hydraul Eng, March. Geomorphology 1 — Soulsby RL Bed shear stresses due to combined waves and currents.

An overview of the G-8 Coastal Morphodynamics Project. Delft Hydraulics, Delft, the Netherlands, pp — Cont Shelf Res 24 1 :1— Sediment Geol — Continent Shelf Res. Earth Surf Process Landf — Aqua Publications, Amsterdam, the Netherlands, p Geol mijnbouw — J Sediment Petrol 28 4 — Global and planetary change, vol Elsevier, Amsterdam, pp — Walling DE The impact of global change on erosion and sediment transport by rivers: current progress and future challenge. WWDR scientific paper.

Winterwerp JC Stratification effects by cohesive and non-cohesive sediment. Xu J Trends in suspended sediment grain size in the upper Yangtze River and its tributaries, as influenced by human activities. Hydrol Sci 52 4 — Geomorphology 3—4 — Yang SL The role of scirpus marsh in attenuation of hydrodynamics and retention of fine sediment in the Yangtze Estuary. Geometry — Estuaries — The water supply of the region depends largely on surface water accumulated in reservoirs.

The construction of reservoirs for water storage becomes increasingly necessary to meet the growing demand of the population. These reservoirs enable water storage during the rainy season, to provide the resource during the dry season. Most of these reservoirs were built without an integrated planning, and this led to a chaotic system, extremely difficult to control MAMEDE et al.

This water retention, on the other hand, allows a better spatial distribution of water resources, favoring its use by surrounding communities. The main negative impacts of this dense network are high evaporation from the surface reservoirs which leads to reduced water availability and increasing complexity of management system. This study will analyze the impacts of the dense reservoir network from Pereira de Miranda catchment also known as Pentecoste on sediment transport in the basin, with retention of the sediment part that would deliver to the reservoir and consequent alteration in the water storage capacity of the system.

The Pentecoste catchment has an average annual rainfall of As regional rainfall regime shows high intra-annual and inter-annual variability with rainfall concentrated in few months, usually between February to May, there is a large number of surface reservoirs for water storage during the wet season and availability of this resource during droughts.

Still, in case of emptying of the reservoirs, local water demand is provided by emergency projects of pipelines to collect from larger water reservoirs or even with the use of water trucks. Identification of reservoirs - In order to quantify the number of reservoirs in the basin satellite images from and were obtained Orbit: ; Point: The images were georeferenced and then classified using the Bhattachary technique, which is a classifier supervised by regions. After classification of the images, a database was generated containing the area for each of the reservoirs identified, resulting from the comparative analysis of these images.

The estimated volume stored in the reservoirs began with a survey of the area and depth of ten reservoirs in the field; thus, obtaining the parameters to calculate the level-area-volume of these reservoirs. We adopted the outline method, which is a survey of the reservoirs outlines at different periods with their associated depths.

The reservoir area Ai on the technical visit was estimated from survey points along its outline, using an instrument of global positioning system GPS - Garmin , with average accuracy of 3 m.

The maximum reservoir area A max , in turn, was obtained from the processing and comparison of images of wet periods from the years and , considered atypical with relatively higher annual precipitation. Therefore, it was assumed that the outlines surveyed on the images corresponded to the maximum area of the reservoirs. Having the depth values and corresponding areas, the reservoirs volumes were estimated from the use of truncated cone formula Equation 1. The procedure consists in calculating the cone volume V i represented by h i height and A i area.

Wherein: c and d are empirical constants described by the reservoir geometry with mean values of 2. In order to verify the Molle equation efficiency, the values obtained were compared with those resulting from the truncated cone equation and analyzed by the Nash - Sutcliffe coefficient. To estimate the maximum volume of the other reservoirs surveyed in the images, which have no geometrical information, the Molle equation was used again.

With these data, it was possible to estimate the maximum water storage capacity of Pentecoste catchment. Erosion - The Universal Soil Loss Equation Equation 4 was used to estimate the erosion in the basin, which was developed in a temperate region in the United States, but it is widely applied in Brazil, as follows:. The method for calculating each of the parameters is detailed in LIRA The localized erosion is estimated by overlapping and multiplying the maps obtained for each parameter from USLE.

The average annual R factor was obtained for each of the 33 rainfall gauging stations in the basin and spaced in the basin from isohyetal generated by interpolation for the period The criterion for selection of these rainfall stations was the existence of historical series with data recorded for more than ten years. This information applies to farm dams excavated earth tanks with a natural catchment or catchment banks.

Farm dams with a well constructed roaded catchment rarely accumulate much debris or silt. Do you have a silt trap? If you do, then you can easily clean silt from the trap; if you don't, then the dam will gradually accumulate organic material and silt from the catchment. See guidance below on how to create silt trap. Desilting will increase the storage volume of a dam and remove the accumulated organic material and nutrients that provides growing conditions for aquatic weeds and algae.

A dry dam provides an opportunity for machinery access that would not normally exist. While machinery is on-site, the overflow, dam seal or inlet can also be maintained. Cleaning out dams before any summer storms is a wise move because the opportunity may not come again for some time. You can use a bulldozer, scraper or excavator on a dry dam base to remove silt, taking care to not break the dam seal.

Removing silt from a wet dam is complicated and can be dangerous and expensive. The km long semi-stationary waters upstream of a dam that is being constructed on the river are expected to be clogged by silt and polluted by a steady build-up of huge quantities of raw sewage and factory pollutants, thus becoming the "biggest open sewer in the world". Large quantities of silt will also build up behind the main dam wall itself.

Sediment is an essential component of soils and an agent of the transportation of nutrients and essential minerals. Thus sediment is both a hazard and a resource. It is currently published as a searchable online platform with profiles of world problems, action strategies, and human values that are interlinked in novel and innovative ways.

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