Reforested Stormwater Basins: A Help or Hindrance to Stormwater Management in Lexington, KY?

Reforested Stormwater Basins: A help or hindrance to stormwater management in Lexington, KY? Abstract Urban development causes significant changes to how water moves through ecosystems, primarily by increasing the land area covered by impermeable surfaces such as concrete and asphalt. Rather than slowly soaking into the soil, rainwater quickly runs off impermeable surfaces and enters streams, causing flooding and other problems. In Lexington and other cities of a similar age, a significant amount of stormwater management infrastructure relies on engineered structures such as culverts and basins to quickly move stormwater away from the built environment. However, in recent years, urban planners and developers are turning to “green infrastructure,” such as strategically placed rain gardens and buffer strips, to help manage stormwater. Lexington has a suite of detention and retention basins designed to manage stormwater without trees, but these sites have been identified by some as a target for reforestation to increase the city’s tree canopy and help improve stormwater management functions. These basins must be monitored in order to evaluate whether planting trees in stormwater basins improves or detracts from their designed function. The proposed project will monitor five treed and five mowed stormwater basins around Lexington to assess 1) whether planted tree biomass will reduce the stormwater storage capacity of monitored basins; 2) whether reforested basins or mowed basins present higher maintenance and management costs; 3) whether reforesting basins influences infiltration rates; and 4) whether reforesting basins influences water table depth in stormwater basins. In addition, this project will evaluate infiltration rates and soil water storage capacity in reforested sites around Lexington (planted as part of Reforest the Bluegrass) to evaluate whether reforestation outside of stormwater basins might support stormwater management objectives. Data from these assessments will inform communications to stormwater managers and community members about urban reforestation as a component of the stormwater management toolkit. Furthermore, the project team will host field days for stormwater managers and community members to better facilitate engagement with project results and sites. This study will provide a framework for evaluating to what extent reforestation should be pursued as a stormwater management approach in Lexington. These data will also contribute to the broader literature exploring “nature-based solutions” in addressing environmental issues.