River Management

River Management

1. Hard engineering

   • Dams and reservoirs
     • Huge walls built across rivers to store water
     • Aims to store water and control the discharge
       • Water is released at a steady flow throughout the year to prevent flooding from high levels of discharge
   • Levees
     • Increasing height of riverbanks and creating parallel riverbanks
   • Diversion channels
     • When the water level is too high the water is diverted elsewhere, often have gates
   • Channel straightening
     • Removal of meanders etc.
     • Velocity of the river increases due to efficiency increases
       • The water is moved out of the area as quickly as possible

2. Soft engineering

   • Land use management (floodplain zoning)
     • Limiting land use to allow natural flooding
     • Land used as a sponge to absorb discharge
   • Wetland and river bank conservation
     • Protecting existing river channels and valleys
     • Conserving wetlands and riverbanks provides natural protection
       • More interception = less discharge
   • Forecasts and warnings
     • Monitoring of weather to predict rainfall to give time to prepare for flooding
   • River restoration
     • Returning rivers back to their original state
     • Removal of any management methods to allow it to flood naturally upstream to prevent flooding downstream in towns
   • Soft engineering: case study
     • River Quaggy - Tributary of the River Thames
       • Flowing north
       • Source at Locksbottom
       • Large number of green space (unusual)
     • How was it managed?
       • Artificial channels and culverts underground
       • Widening and deepening was considered - QWAG didn't choose it because it aims to improve the local environment
     • What methods were used?
       • River was bought back to the surface by cutting a new channel
       • A new lake was created to take water when full
         • Holds 85,000 square metres
       • The park was lowered and shaped into a flood plain
     • Effects
       • Reduced risk of flooding to 600 homes and businesses
       • Created a diverse environment for wildlife
       • Land can't be built on
       • Cost of maintenance
       • Conflict - land is needed for affordable new buildings
       • Doesn't stop flooding overall