Category: Irrigation and Water Engineering

There are different types of weirs. It may be a simple metal plate with a V-notch cut into it, or it may be a concrete and steel structure across the bed of a river. A weir that causes a large change of water level behind it, compared to the error inherent in the depth measurement…

Weirs are used in conjunction with locks, to render a river navigable and to provide even flow for navigation. In this case, the weir is made significantly longer than the width of the river by forming it in a ‘U’ shape or running it diagonally, instead of the short perpendicular path. Since the weir is…

A weir, also known as a low-head dam is a small overflow-type dam commonly used to raise the level of a river or stream. Weirs have traditionally been used to create mill ponds in such places. Water flows over the top of a weir, although some weirs have sluice gates, which release water at a…

Construction of a hydroelectric plant requires a long lead time for site studies, hydrological studies and environmental impact assessment, and are large-scale projects by comparison to traditional power generation based upon fossil fuels. The number of sites that can be economically developed for hydroelectric production is limited; new sites tend to be far from population…

The impact on human society is also significant. For example, the Three Gorges Dam on the Yangtze River in China will create a reservoir 600 km long, to be used for hydro-power generation. Its construction required the loss of over a million people’s homes and their mass relocation, the loss of many valuable archaeological and…

Impact is assessed in several ways: A large dam can cause the loss of entire ecospheres, including endangered and undiscovered species in the area, and the replacement of the original environment by a new inland lake.

One of the best places for building a dam is a narrow part of a deep river valley; the valley sides can then act as natural walls. The primary function of the dam’s structure is to fill the gap in the natural reservoir line left by the stream channel. The sites are usually those where…

The common purposes for the construction of dams are as follows:

Dams can be formed by human agency, natural causes or even by the intervention of wildlife such as beavers. Man-made dams are typically classified according to their size or height and intended purpose or structure. By size International standards define large dams as higher than 15–20 m and major dams as over 150–250 m in…

Early dam building took place in Mesopotamia and the Middle East. Dams were used to control the water level, for Mesopotamia’s weather affected the Tigris and Euphrates rivers, and could be quite unpredictable. The earliest known dam is situated in Jawa, Jordan, 100 km northeast of the capital Amman. The Ancient Egyptian Sadd Al-Kafara at…