Flood and erosion defences on the river Mersey

We will learn: The different flood and erosion defences on the river Mersey The different flood and erosion defences on the river Mersey How these solutions work How these solutions work Tasks: Make a list of the types of flood defences and describe them Make a list of the types of flood defences and describe them Visit survey sites along the Mersey and identify the type of erosion or flood protection you see. Visit survey sites along the Mersey and identify the type of erosion or flood protection you see.

Causes of flooding on the Mersey Large catchment area, (Peat on Gritstone) Large catchment area, (Peat on Gritstone) Catchment area is in the hills of the Peak District. Prevailing winds are moisture laiden. Rain can be persistent. Catchment area is in the hills of the Peak District. Prevailing winds are moisture laiden. Rain can be persistent. Steep sided valleys down to Stockport. Steep sided valleys down to Stockport. Large areas of hardsurfaces in Stockport and South Manchester drain quickly into it. Large areas of hardsurfaces in Stockport and South Manchester drain quickly into it.

Flood damage On the map shade in areas next to the river (and Tributaries) that are at risk of flooding. These areas will be within one contour line from the river. On the map shade in areas next to the river (and Tributaries) that are at risk of flooding. These areas will be within one contour line from the river. Shade in a different colour, areas within this area where buildings are at risk of flooding. Shade in a different colour, areas within this area where buildings are at risk of flooding. Create a key on your map to explain these shadings. Create a key on your map to explain these shadings.

Hard Engineering: Generally defined as a controlled disruption of natural processes using man made structures. Soft Engineering: Use of ecological practices to reduce erosion and stabilise river banks while enhancing habitats and saving money. River Flood defence and erosion protection definitions

Dams Hard engineering

Deepen the river/Dredging

Hard engineering Levees Embankments/Levees

Embankment / Levee

Hard engineering Straighten Channels

Hard engineering Bank reinforcement with Gabions (steel baskets) Bank reinforcement with Gabions (steel baskets)

Hard engineering Banks reinforced with concrete

Hard engineering Overflow Channels

Soft engineering Plant trees / Forests

Soft engineering Allow Flooding

Soft engineering Planning: Local authorities 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. Planning: Local authorities 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. There can be resistance to development restrictions in areas where there is a shortage of housing.

Flood Defences Draw a spider diagram to show the different soft and hard engineering solutions for protection the land beside rivers from erosion and flooding. Write a short sentence to describe each one.