Why is stormwater management important?
Storm water (or rainwater) needs to be managed responsibly so that the impacts of high rainfall events are mitigated by the changing land use of urban cities. Before human urbanisation, most of the planet’s land surface was permeable.
Storm water (or rainwater) needs to be managed responsibly so that the impacts of high rainfall events are mitigated by the changing land use of urban cities. Before human urbanisation, most of the planet’s land surface was permeable.
A permeable surface is one that allows liquids (and gases) to pass through it. By way of example, grass is a permeable surface in so far that it allows water to infiltrate into the Earth below. This infiltration of rainfall allows the stormwater to enter the groundwater system, store in underground aquifers and slowly move through the underground soil matrix to rivers and oceans.
When we create impermeable surfaces (the opposite of permeable surfaces), we create a barrier to this important part of the water cycle, which can create future stormwater management issues.
How do you implement stormwater management in a catchment?
In cases where catchments have a high concentration or high percentage of impermeable surfaces there is an increased risk of flooding in that catchment. Good stormwater management reduces the effects of flooding risks on communities by creating structures and systems that mitigate flooding in high rainfall. These structures and systems include things like stormwater detention tanks, detention ponds (these can be an effective way to hold back the water which I that would ordinarily have permeated through the ground), or even constructed wetlands that also help to treat the stormwater as well as mitigate flooding.
3 examples of stormwater management options:
- Flood mapping and public education – undertaking a flood study of catchments where there is an urban population and educating new and current property owners of any associated flood risk. This also includes including the flood risk of catchments into decision making about land development, particularly subdivision.
- Offsetting flows from additional development – If additional impervious surfaces are added to the catchment, the associated increase in runoff should be managed to store the volume of water until the main storm event has passed. This is not always practical but should be encouraged where possible.
- Restabilising stream and riverbanks and beds – restoring natural flow paths is just as important as ensuring those paths can handle the flow associated. Keeping the stream banks and stream beds vegetated and stabilised will increase the resilience of the stream system to cope in high rainfall events and reduce the risk of erosion and degradation of the stream ecosystem in the future.
Conclusion
Without good storm water management, there could be significant impacts on local communities and the greater environment. Flooding of private properties and damage to public infrastructure, as well as erosion and destabilization of stream and riverbanks are just a few of the impacts. Where there is a man-made impact on the stormwater flow in a catchment it is prudent for the public authority of that area to mitigate the risks to the community and the environment.
About the Author
Amanda Siqueira is an Australian civil and environmental engineer who has worked in design, construction and remediation of drainage and sewer pipes in Australia, New Zealand and the UK. She has passion for all things pipes and is also one of the Co-founders of VAPAR.
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