Stormwater Management in the Home Landscape
Article by: Jessica Warren, ANR Agent, Camden County
Living on the coast, stormwater management is one of the most prevalent issues in the home landscape.
Our high rainfall, high water table, and often poorly draining soils all contribute to our flood risk. Though we may not be able to completely prevent impacts from hurricanes or tropical storms, there are practices that we can implement in our landscapes that improve our odds and reduce stormwater impacts. These practices not only improve the quality and health of our home landscapes, but also improve the health of our local waterbodies by reducing runoff and filtering stormwater.
Stormwater is any precipitation that falls on the landscape due to a recent weather event. Stormwater can infiltrate into the ground, be stored in surface waters, evaporate, or run off the land. Runoff is precipitation that hits saturated or impervious ground (parking lots, driveways, roofs, sidewalks, roads, etc.) and flows overland downhill – and this is what we want to prevent with our stormwater. Stormwater runoff can cause flooding that damages homes, businesses, and roads. It also erodes topsoil reducing soil health, and picks up pollutants such as sediment, nutrients, metals, fertilizer, and animal waste as it runs to water bodies – contaminating recreational waters and aquatic wildlife habitat. The movement of stormwater across natural landscapes depends on slope, type and density of vegetation, soil structure, subsurface drainage patterns, and the frequency and force of storm events.
We often underestimate the amount of stormwater runoff that we create with the impervious surfaces in our home landscapes. For instance, in a rain event producing one inch of rainfall, there are 623 gallons of runoff for every 1000 square feet of impervious surface. This includes your roof, driveway, patio, sidewalks, and any other roofed or concrete areas. A 3000 square foot roof would produce 1869 gallons of runoff (not including the driveway and other surfaces) with every inch of rain. In an area that receives 54 inches of rain per year on average, that’s a lot of stormwater runoff.
One of the best things that you can do to reduce stormwater impacts in your landscape is to plant and preserve trees. A healthy 100-foot-tall tree can take 11,000 gallons of water from the soil and release it back into the air as oxygen and water vapor each growing season. Trees can absorb between 10 and 150 gallons of water daily. This is why we see much standing water and flooding in our community after a property is clearcut. As always, it’s important to plant the right plant in the right place, so if you have issues with wet soils or standing water you should plant a tree that is tolerant of wetland type conditions such as a red maple, sweetbay magnolia, or black willow.
Other practices that we can utilize in our home landscapes include rainwater harvesting, permeable pavers, and rain gardens. Rainwater harvesting can be done by installing rain barrels (most common and cheapest) or cisterns to collect rainwater from a roof or other impervious surface. This non-potable water can then be used to water gardens and other areas as needed. In addition to conserving water, reducing runoff, and saving money, this practice is better for your plants. Plants prefer rainwater, especially if you’re watering from a municipal source. Permeable pavers, porous asphalt, and pervious concrete are all options to reduce the impervious surfaces in your landscape such as driveways, sidewalks, and patios. These surfaces allow water to infiltrate through instead of running off and help filter stormwater as it works its way back to the aquifer. Raingardens reduce water pollution and runoff volumes, while cleaning stormwater as it infiltrates. They are a low maintenance, beautiful landscape feature, that provides habitat in the landscape for pollinators and wildlife. Rain gardens are typically planted with native plants that are adapted to wet conditions. Native plants are lower maintenance, are better adapted to climate and conditions, and provide better habitat and resources for pollinators and wildlife. A 100 square foot. rain garden can often receive water from an area 5 to 10 times larger than its size. A typical rain garden depth is 6-8inches, and ponding should last no more than 48 hours after rain stops. Because of this limited ponding time, rain gardens do not increase mosquito populations. UGA Marine Extension and Georgia Sea Grant has some great resources on implementing these and other stormwater practices available on their website.
The goal of all stormwater management practices is to promote stormwater infiltration to soils and surface aquifers, prevent flooding and damage, protect surface waters and aquifers from contamination, and prevent soil erosion. We can all make some simple choices in our landscapes to minimize stormwater impacts to our homes and our communities.