Water Resources Research Act Program

Details for Project ID 2014SC94B

Low Impact Development (LID) Strormwater Management Techniques as a Tool for Mitigating Climate Change Induced Increases in Rainfall Intensity and Frequency

Institute: South Carolina
Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $23,254 Total Non-Federal Funds: $46,508

Principal Investigators: Nigel Kaye, William MartinIII

Project Summary: Problem: Global Climate Models (GCMs) predict a warmer moister atmosphere which will result in more extreme rainfall events. As such, the design storms used in current stormwater guidelines will change and the depth of given return period storms will increase. Current SC DHEC regulations require new land developments to design stormwater management infrastructure to match the pre-development and post-development peak runoff for 2 and 10 year return period storms. As such, existing infrastructure designed to this standard will become increasingly stressed by more intense rainfall events. This will lead to increased runoff, increased probability offlooding downstream, and reduced water quality due to increased erosion and sediment transport . This will likely require retro-fit of existing . Further, new land developments will also need to be designed with climate change in mind. The fundamental problem to be addressed is how to design new infrastructure (or retro-fit existing infrastructure) such that it is more resilient to changes in rainfall patterns. The focus of the proposal is on the management of the quantity of runoff from a given land development and will not explicitly address water quality in the modeling work. However, the effective management of water quantity will reduce erosion, and reduce the rate of sediment transport off site which will directly improve the quality of downstream receiving waters. Reduction in runoff will also increase ground water re-charge. Objectives: The proposed research will achieve the following objectives. (1) Assess the impact of climate change on 1, 2, 5, 10, 25, 50, and 100 year return period storm depths for each county in South Carolina. Downscaled data for 134 different GCM runs covering 85 model years will be analyzed to establish revised design storm depths. (2) Assess how Low Impact Development (LID) stormwater practices can be used to mitigate the effects of climate change. Three different land development case studies will be developed with both traditional and LID designs created for each case using current DHEC regulations. The three case studies will each be modeled at three different locations within the state (upstate, midlands, and coastal). Each design will be assessed for its resiliency to changes in rainfall storm frequency . (3) Develop a set of guidelines . for climate change resilient stormwater design in South Carolina . The guidelines will be based on an analysis of the case studies and will provide guidance for both new land developments and for the retro-fit of existing stormwater infrastructure. The results will be presented at the South Carolina Water Resources Conference. (4) Develop training materials for use by the Clemson University extension service in practitioner and community outreach through the. Methods: The research team will use downscaled Global Climate Model (GCM) data to examine predicted changes in rainfall patterns across the state. The team will then develop a total of 90 case studies to examine the effect of these changing rainfall patterns on both standard and LID stormwater design methodologies. The case studies will look at different LID technologies (porous pavements, infiltration trenches, and green roofs) applied to different size and types of land developments in different geographic locations within the state of South Carolina (Upstate, . midland, and coastal). The resiliency of each design approach will be judged by its ability to replicate the pre-development site hydrology for a range of rainfall depths. The resulting analysis of design resiliency will be published in archival research journals and will be used to develop training materials for use by the Clemson University Extension Service for use in their outreach work with design engineers and community organizations through their Water Resources Program.