Overland flow mitigation
Overland flow is water that runs across the land after rainfall, either before it enters a watercourse or after it leaves a watercourse as floodwater, or after it rises to the surface naturally from underground. This section of the guide does not cover overland flows that are passively taken (e.g. levees banks and diversion banks) or actively taken (e.g. pumps, drains and storages). This section focuses on land modifications that are intended to interfere with but not ‘take’ overland flow water. These include contour banks, flood mitigation structures and strip cropping. Overland flow is of critical importance to healthy waterways. The Water Act 2000 has provision to regulate overland flow in order to ensure adquate environmental flows and the long-term security of water for water users.
The direct impacts of overland flow mitigation may include:
- Reduced soil erosion
- Reduced water nutrient concentrations
- Increased plant available water due to increased time for infiltation
- Reduced stream flow
Last updated 7 September 2010