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Evaluate the role of hard and soft engineering strategies in managing rivers

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Introduction

´╗┐Evaluate the role of hard and soft engineering strategies in managing rivers Libby Flynn 12F Hard engineering strategies tend to be the more expensive strategies, and can also cause a negative impact on the landscape and environment. Channelization of the river channel removes meanders to reduce the length of the river so the water flows faster downstream. The faster flowing water washes away sediment that has accumulated on the river bed minimising the risk of flooding, as well as the flow of the water deepening the river which means there is an increase in the capacity of the river, also reducing the risk of flooding. However, this strategy can cause problems further downstream as there is an increase in the speed and discharge, so areas that do not have flood defences are more vulnerable and the risk increases. This is also a very expensive method and a lot of resources and manpower are required. An example of where this particular strategy has been used is the Kissimmee River in Florida, where the river channel was shortened from 103 miles to just 56 miles in length. ...read more.

Middle

As well as this, dams and water control structures are very expensive to build and require a lot of resources and so are not always economically sustainable, which can be seen from the construction of seven dams in Bangladesh, costing approximately $30-40billion and would take forty years to build. They would then need continuous maintain which would also be costly, putting great strain on the government. They can also be seen as socially unsustainable as people can be forced to move off their land if it is to be used to store the water. Overall, measures such as dams and water control features are effective at holding back the water and regulating flow yet they are expensive and not always sustainable. Embankments are raised banks along the river, enabling it to increase its capacity and deepening the channel, meaning more water can be held in the river before it reaches bank full discharge and floods. 7500 km of flood embankments have been built in Bangladesh since 1947 and have been effective at holding back smaller floods. ...read more.

Conclusion

Land has different building controls depending on how far from the river the buildings lie. The land next to the river is unused land and as the distance from the river increases so does the value and land quality, as these are areas less likely to flood. However, this is not always effective as they can be ignored and do not actually prevent flooding, just help to lessen the impacts. They can also cause problems as people who live in high-risk zones will face a rise in insurance prices. Afforestation is economically sustainable as it is not too expensive, environmentally sustainable as it creates habitats and therefore can help increase biodiversity and socially sustainable as it does not affect anyone. However, it is not always effective as it takes years for the trees to grow and they only intercept a certain amount of rain so will not prevent extreme floods. Overall, hard engineering strategies such as embankments, water control features, dams and channelization are more effective than soft engineering strategies such as washland areas and land use zoning. However, hard engineering strategies tend to be a lot more expensive and costly to the environment. ...read more.

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