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Hard & Soft Engineering

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Introduction

Flood Control - Hard & Soft Engineering Techniques Rivers are a natural flow of water, and since the beginning of time, humans have tried to harness the energy of rivers and change their direction. This interference often leads to flooding. Sometime when a river floods it becomes necessary to intervene with its course and use modern techniques to reduce the risk of flooding and to ensure the passage of water flows downstream and away from the affected area as quickly as possible. Hard Engineering Techniques Below are diagrams explaining some commonly used hard Engineering Techniques: Revetments. Brick, concrete, wooden pile, sheet steel, rock or wire mesh structures designed to reduce bank erosion and to prevent meander development and thus to protect homes and farmland from erosion. Wing Dykes and training walls. These built out from the bank towards the centre of the channel in order to direct the fastest river current or thalweg away from the bank. This decreases bank erosion and increases the river's velocity in the centre so that it erodes a deeper, navigable channel, which is self-dredging. ...read more.

Middle

To reverse this, the old meander is re-opened or a new one is constructed, to allow the river to flow back on its original route. By causing a river to meander, it slows down the velocity and speed of the river. Forestation.Trees are planted near to the river. By doing this, it means improved interception of rainwater and lower river discharge. This is a relatively low cost option, which enhances the environmental quality of the drainage basin. Planning. Local authorities and the national government introduce policies to control urban development close to or on the floodplain. This reduces the chance of flooding and the risk of damage to property. There can be resistance to development restrictions in areas where there is a shortage of housing. Enforcing planning regulations and controls may be harder in LEDCs. Different interest groups have different views about flood management techniques: * Governments and developers often favour large hard engineering options, such as dam building. Building a dam and a reservoir can generate income. ...read more.

Conclusion

Backwaters were also engineered into the restored river. These are important for a diverse habitat, and in times of high water provide a calm pool of water for young fish and insect larvae. Along the meanders, willow cushions were used to stop the river from eroding the sides of the bank. Where this was not possible, trees were planted in close proximity to the bank, so that their roots would hold the bank together, not only were they used for this purpose but to catch surface rainfall and run-off, therefore slowing down the time it takes for water to enter the river, and reducing the risk of the river flooding. The wider benefits of river restoration using soft engineering to restore the river back to its original state are: * Better management of floods, droughts and water quality * Increasing the public awareness of past river management and encouraging the use of softer techniques * A huge increase in the benefit to the environment. ...read more.

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