January - Snow melt and heavy rain fall in the alps.
Water logged soil
31/2 times more rainfall in that month
Where the river flows it is in a gorge which restricts the amount of land able to soak up water.
Human
3x more area had been built on compared to 1900
Heavy cultivation = compacted soil
Narrowed the river width = fast flow/down stream
River channel had been straightened = 50km shorter than it used to be
5 days rather than 2 discharge is double
Contour ploughing - down to the river
Deforestation in the alps reduced interception and soil storage of water
Rate of surface run off increased
Urbanisation of the floodplain, with water flowing off roofs and roads into drains leading directly to
the river has greatly increased river levels after heavy rain.
Raising the levees has caused flood plain area to be closed off
Affects
Schools were flooded out
Had to move places
Shops closed - economic effect
150,000 evacuated from the Poulders (below sea level area)
Cattle picked up viral infection
1 person dead
250,000 people and millions of farm animals evacuated
1550km2 farmland flooded
City Centre of Cologne flooded to a depth of 2 meters
Hundreds of homes inundated
Solutions
Levees on the edge of the rivers
Raises the height of the river
Can lead to disaster because the water level rises as the sediment increases
Contour ploughing - with the contours
Surface run off is slower
Flood proofing
Up the carpet/make changes to down stairs
Reduced damage
House design which raises the floor
Interior room design which minimises damage e.g. tiled floor.
Light furniture which can be quickly moved up stairs to avoid flood water
Removable flood walls that can be opened in summer to provide a river view
Local authorities are now controlling the location of new building
Dams and Reservoirs
Built up stream for hydro-electricity and to regulate river flow.
To control the flow of water.
Water Supply
Improve navigation
Reduce soil erosion
Affrestation
Trees delay and reduce the amount of water reaching the river