Harvesting rainwater makes good sense for landscape
May 17, 2010
LINCOLN, Neb. – When it rains in Nebraska we usually are thankful for the moisture. Why then do we design our properties and landscapes to move rainwater away as quickly as possible? Why not harvest some of the rain to help conserve water resources?
Rainwater harvesting is not a new concept, but it is making a comeback in practices such as rain barrel use. Rain barrels are fairly limited in the amount of rainwater they collect, but newer methods are also being used. Bioretention gardens, rain gardens, planter boxes, vegetated swales and green roofs are examples of rain harvesting methods being used in home, business and community landscapes.
Water is a precious and limited natural resource whose value is ever increasing. How we view rainwater run-off is changing. Traditionally, in urban communities, rainwater is referred to as stormwater and treated as something to be moved off site as quickly as possible via curbs, gutters, storm drains and pipes (gray infrastructure).
Water run-off, from rain and snow melt, is beginning to be viewed as a resource to capture and reuse or allow to infiltrate (soak) into soil through the use of green space features such as rain gardens (green infrastructure). When this is done, the volume of stormwater run-off from a property is reduced, water is returned to soil to increase soil moisture, and pollutants are filtered.
As stormwater flows from roof tops and across surfaces to storm drains, it picks up pollutants such as sediment, fertilizer, grass clippings left on sidewalks, and oil dripped on driveways. Stormwater is not treated to remove pollutants. It is discharged from curbs to storm drains to streams, rivers and lakes, taking pollutants along with it which impairs surface water quality.
Designing and installing landscapes features to harvest rainwater not only conserves and protects water resources. It also can save money on water bills, increase property values, conserve energy by cooling the environment, improve air quality by plants absorbing air pollutants, and enhance the aesthetics of residential and community landscapes.
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For home landscapes, rain barrels, rain gardens and the use of porous surfaces such as bricks on sand or porous pavers for patios are rain harvesting methods being used. Don’t overlook simple roof downspout redirection. In place of water from downspouts being directed to a paved area, redirect it to a planted area away from the building.
Redirecting downspouts to a rain barrel or rain garden is an even better option. Today’s rain barrels are screened to keep out mosquitoes and designed to direct overflow away from a building’s foundation. To remove water from a rain barrel, spigots are attached near the base for garden hose connections.
Although rain barrels are a common way to harvest rainwater, a typical 55 gallon barrel is limited in how much rain can be collected. This is why they are designed for overflow with the overflow being directed to another rain barrel, plant bed, or rain garden.
Rain gardens are fairly shallow depressions of nearly any size with amended soils. They have small berms on three sides and are located where they capture rain from a downspout, lawn, or paved area such as a driveway.
Rain gardens are typically planted to deep rooted native perennials and grasses that tolerate very short periods of pooling water, but otherwise dry conditions between rain events. Most plants used in rain gardens are readily available and currently planted in Nebraska gardens.
A concern with rain gardens is they will have standing water and breed mosquitoes. This is not the case. Surface water in a properly designed and installed rain garden will infiltrate and be gone in 48 hours or less with 24 hours being ideal.
To learn how to design and install a beautiful, functional rain garden, NebGuides covering design, construction and plant selection are available at http://ianrpubs.unl.edu. Type stormwater or rain gardens in the search box to locate these guides.
Another University of Nebraska-Lincoln resource for information on rainwater harvesting and other best management practices for conserving and protecting water resources is the UNL water Web site, water.unl.edu. The rain garden NebGuides also can be found at this site in the Lawns, Landscapes and Gardens section.