The answer to the question of why stormwater harvesting matters is double-pronged. See, stormwater management strategies such as catch basins, ponds, cisterns, and barrels can help us accomplish two goals at once:
- Stop stormwater from running off into waterways, picking up pollution and disease, and damaging properties along the way. This also prevents it from causing damage to ecosystems and wildlife.
- Use that stormwater for a good purpose, such as in agriculture (assuming it is clean), landscaping, or – once purified – for drinking.
More specifically, stormwater harvesting strategies help to:
- Reduce peak runoff: Peak runoff is the high point of stormwater after a precipitation event. It’s the time when sewers are most likely to overflow, drains to back up, and streams to overrun their banks. This is when pollution, erosion, and disease become most likely. Stormwater harvesting can help to remove great volumes from the water supply, reducing peak runoff and making sewer and stream overflows less likely. Rain barrels, cisterns, ponds, and gardens all snatch water out of the air, significantly reducing peak loads.
- Reduce or prevent downstream flooding: Even in areas that don’t experience the precipitation event, stormwater can still pose a significant risk. Think about a community of riverfront properties far downstream from a flood, for instance. Even if they aren’t getting rained on, that water still has to go somewhere – and it’s going to go downriver, causing damage to waterfront real estate. Any time you can remove stormwater from the system, you’re doing a favor to the downstream environment.
- Greater replenishment of aquifers: It’s awesome when a stormwater management strategy – such as a large bioswale or drainage plain – can funnel water down into the aquifer. This is what we draw on during dry times, what our wells and municipal water supplies tap into, so we want to keep aquifers healthy and full. However, stormwater harvesting can also accomplish this. When we collect water in cisterns or barrels, on green roofs, or in ponds, we always have the option of funneling it down into the ground using pipes. It’s a great way to reduce runoff and give back to Mother Earth at the same time.
- Provide an ecosystem for animals: Many landowners create retention ponds to harvest stormwater, then enjoy those ponds all year round. When created at low points on the property, they become natural ecosystems rather than boggy mosquito breeding grounds. Plus, if you have the permits to connect them to nearby waterways, you can help relieve some of the pressure of overflowing streams. Then native wildlife can flock to the pond, using it for sustenance and shelter.
- Water supply creation: Depending on the size of the stormwater harvesting strategy, you can use the collected water for various applications. Rain barrels can make a huge difference for garden plants, while retention and detention ponds (discussed in “Largescale Stormwater Harvesting”) can potentially water acres of land. A rooftop setup that uses lined cisterns can potentially produce enough water for an entire family or building, assuming they have the correct capacity and filtration ability.
Before we go any further discussing specific stormwater harvesting strategies, however, it’s time to take a look at an idea that’s gained a lot of traction in the last several decades: green infrastructure.
