Flood Plain Zoning Flashcards
Flood plain zoning
Where land in a river valley is used in such a way as to minimise the impact of flooding.
In the Uk…
In the UK the environment agency categorises into four flood risk zones and issues flood risk maps. Local authorities are required to use these maps to produce flood risk assessments in order to guide decisions about new building applications.
Housing in the Uk
There is a housing shortage in the UK and restricting building increases the problem. Restricted supply will increase house prices.
Cost
It is low cost there are only administrative costs involved.
Planning permission
It is difficult to get planning permission or extend homes on the flood plain.
Green space
Protecting the flood plain provides a welcome green space in UK towns.
Habitats
Habitats are destroyed due to increased building on other green sites.
Water meadows
Tradition water meadows by a river are protected from development.
Impermeable surfaces
The amount of impermeable surfaces is decreased by restricting building on the active flood plain.
Impact on UK
The approach has limited impact as UK cities and towns have already sprawled over the flood plain.
Zones
River Red zone - Avoid areas very near river Orange zone - Pasture for grazing Playing fields Roads + car parks Light green zone - Industry Dark green zone - Housing
Afforestation
Trees are planted near to the river. This means greater interception of rainwater and lower river discharge. This is a relatively low cost option, which enhances the environmental quality of the drainage basin.
Afforestation cannot prevent flooding but it can help reduce its likelihood.
Washlands
These are areas of land where water can wash into during a flood. They are usually found in the lower course of a river. Sluice gates will be opened to allow excess water to flow into the area and flood marginal land.
It is not always easy to find acceptable areas for this to happen – especially in areas where there are many cities.
Land use zoning
When planning for a new settlement in an area, this can be used to divide up the flood plain into areas which experience different levels of flood risk. Red areas will be places that are likely to experience a high degree of flood risk. Yellow areas will be places where flooding is possible but unlikely. Green areas are places where it is very unlikely that any flooding will take place.
This is effective when making decisions about new building in an area but does not work in areas that are already built up.
