Effects of urban residential landscape composition on surface runoff generation

Lawns have long been a primary feature of residential landscapes in the United States. However, as population growth in urban areas continues to rise, water conservation is becoming a key priority for many municipalities. In recent years, some municipalities have begun to offer rebate programs which incentivize removal of turfgrass areas and conversion to alternative 'water-efficient' landscapes, with the goal of reducing outdoor water use. The environmental impacts and changes to ecosystem services associated with such landscape alterations are not well understood. Therefore, a 2-year continuous research project was conducted at the Urban Landscape Runoff Research Facility at Texas A&M University to evaluate rainfall capture and runoff volumes associated with several commonly used residential landscape types (including, St. Augustine grass Lawn, Xeriscaping, Mulch, Artificial Turf, and Sand-capped Lawn) and to characterize the flow dynamics of surface runoff in relation to rainfall intensity for each landscape. The results demonstrate that runoff dynamics differ between landscapes, but also change over time as the newly converted landscapes become established. Following the initial months of establishment, the effects of landscape type on runoff volumes were significant, with Artificial Turf and Xeriscaping generating greater runoff volumes than Mulch and St. Augustine grass Lawns for most runoff events, which is partially due to the low infiltration rate of such landscapes. Overall, Artificial Turf and Xeriscaping showed the greatest cumulative runoff volumes (>400 L m^-2), whereas Water Efficient- Mulch, Sand-capped Lawn and St. Augustine grass Lawn had a significantly lower cumulative runoff volumes, ranging from 180 to 290 L m^-2. Information from this research should be useful to municipalities, water purveyors, and homeowner associations as they weigh the long-term hydrological impacts of lawn removal and landscape conversion programs.