River Management Techniques

1. River Management Techniques

2. Hard engineering Winged Dykes- reflects the flow of the water an helps create both deep and shallow in the channel. This enhances biodiversity, making it easier for more varied species to survive. Reservoirs this is a management technique as it stores the water, when held behind a dam. The water can be controlled and help to regulate river flow. However this can have environmental problems such as large dams can increase the risk of flooding downstream due to changes in the sediment.

3. The Structural Approach This involves building defences against the erosive power of the water. This is also seen as hard engineering, such as dams and floodwalls, levees, revetments and dykes, embankments, diversion channels, retention basins, barrages, channelisation Example of a dam could be the Aswan Dam on the Nile. Example of dykes could be the Skearne and Mississippi Levees- are raised mounds of earth which restrict the flow of the river, they are built along the banks of the river, however they do have disadvantages as they prevent the draining of the floodplain which destroys large areas of wetlands and habitats.

4. The Structural Approach • Dams can be used for water storage and hydro-electric power, flood control or regulation of river flow for navigation. Dams regulate water flow through a river, they are mainly built upstream in the middle reaches of a river. • Resectioning this involves deepening or widening the channel to increase hydraulic efficiency and larger discharge. • Realignment- this involves the straightening of the river, this can also be done by lining the bed and banks with concrete so that water velocity and flood waters can move quicker.

5. Soft engineering Agricultural changes- modified cropping practises and soil conservation measures on farmland can influence water flows. Continuous cropping and contour ploughing helps to reduce the amount of surface flow. Afforestation- this increases interception which means that there is less water in the drainage basin at one period of time, reducing discharge. This increases the lag time,and gives time for the river to recover. The best place for this to occur is steep slopes as it prevents fast flowing water as surface runoff.

6. The behavioural approach • This consists of planning ahead to avoid the initial problem. • This could be weather forecasting equipment that warns people of possible flooding. The equipment relays on aerial measurements of rainfall. They are recorded at metrological stations and the data is assessed. Collection of the data can then be sent to the emergency services, local authorities and the public. • Planning restrictions can prevent development on areas prone to flooding. This can also take the form of compulsory insurance and use of specific building regulations such as water proofing basements and ground floors, sealed windows. By doing this it creates a possible floodway through a city in which urban areas are removed and replaced by public space such as parks.

7. The do nothing approach This approach saves money and doesn’t affect the environment. Many believe that the river has existed in its present state for thousands of years and therefore manipulating it would have worse effects than leaving it be.