Catchments are areas of land which supply water to rivers and creeks. They are usually bounded by hills and mountains. Rain and other water which falls on the catchment, then finds its way into our wetlands, creeks and river systems, and ultimately the Brisbane River, into Moreton Bay.
Every square metre of land in Australia is part of a catchment
In natural catchments, water falling on the catchment surface will either become stormwater runoff or groundwater. Plant roots slow down this flow of water so it enter the waterways slowly. Slow infiltration of water into the waterways also purifies it.
In contrast, catchment surfaces of urban areas are often sealed and impervious to water, so little water enter the soil. Here water runs off rapidly and stormwater pipes and drains divert this water into local waterways without treatment. Urban areas create a large volume of fast flowing runoff, which can cause serious flooding and erosion, and contribute to the pollution of our local waterways.
Water links all parts of the catchments. So much so, that the quality of water in our creeks and streams indicates how we use and value the land.
The more polluted our catchments, the more polluted our streams and rivers become.
Urban catchments have:
* Many sealed impervious areas
* Fast-flowing runoff
* Water pollution from stormwater
* Modified stream channels
* Reduced riparian creek bank vegetation