How Street-Side Catchments Can Recharge Soil Water and Revitalize Neighborhoods

The Downside of Conventional Water Shedding

There's a misunderstanding about how rainwater should be handled in our towns. In most Arizona towns, rainwater management is reactive, attempting to minimize damage due to flooding by pushing the water away and downstream as quickly as possible. This approach has several detrimental effects. Runoff never sits in one location long enough to seep in and recharge water tables. Lower water tables affect the surface vegetation, decreasing the amount of moisture the soil can hold. When water is moving faster across the terrain, it carries more topsoil with it, causing erosion, loss of nutrients and diminishing of organic material in the soil itself.

Slowing Water to Allow Infiltration and Reduce Erosion

While moving the water to a central drainage system keeps it from damaging buildings, it increases velocity and causes other issues such as erosion along banks. There are many ways to help diminish the effects of this kind of flood water management. All of them involve slowing the water down with check dams, gabions, dikes, using it in catchments and otherwise giving it time to seep into the ground. Generally, the best ways to go about managing this would be to start at the top of the watershed and work our way down. These practices let water recharge the soil instead of rushing away, preserving organic matter and supporting healthier vegetation every step of the way.

Designing Street-Side Catchments for Rainwater Harvesting

One effective approach is to build water catchments along streets that capture gutter runoff during storm events. This involves digging channels along street-side easements, lining them with rocks to avoid erosion, and partially filling them with wood chips in order to promote their ability to retain more moisture. Along the outer edge, mulch would be buried and indigenous trees, shrubs, grasses and other plants would be planted, using the water that is harvested passively.

Runoff that normally runs along the gutter can be directed into these channels by cutting the curb or using a boring technique. Care is taken to keep structures that slow the water in these channels so that they do not become erosive. Once the basin is filled, the overflow is gently channeled back into the gutter to fill the next basin. The design infiltrates organic matter into the system to provide greater nutrients for the soil itself and hold far more water in the surface soil for longer periods of time.

Benefits for Plants, Pollinators, and the Community

These catchments promote growth of indigenous trees, shrubs and grasses in order to promote greater abundance, provide fruit, help establish pollinator populations, help charge water tables and educate the community about water, plants and sustainable means to grow a variety of plants with water harvesting methods. This promotes a diversity of plant life along the streets, which adds beauty to the city, decreases the temperature along the roads, creates more pollen sources for the various pollinators in the area, attracts more birdlife and other beneficial animals, and provides more edible options for the citizenry. On a wide scale, such practices are capable of providing income for those willing to harvest the fruit these plants will provide.

Community Involvement and Proven Results

The goals of projects like this include exposing the citizenry to responsible water harvesting methods and the benefits they can offer personally. It is hoped that by doing this, citizens will become more interested in other water harvesting methods and more open to learning about how the watershed can be improved from the river all the way up to the mountains. A similar project was pursued in Tucson, with great success. Whole neighborhoods have adopted these strategies, with the city becoming involved and promoting water harvesting rather than water shedding techniques. As residents see the beauty and value of these catchments, they begin replicating the design in their own neighborhoods, bringing real beauty and productivity back to residential streets.