Stormwater Low-Impact Development: A Call to Arms for Hydraulic Engineers

Abstract

Conventional stormwater management teaches that the primary concern is to remove the water from the site being developed (Ahiablame et al. 2012). Therefore, in order to reduce the risk of flooding, impervious surfaces such as parking lots and buildings are fitted with drainage structures made of impervious materials (pipes or concrete). After the water is collected, it is discharged to the nearest stream or lake. This method prevents local flooding, but it can cause problems downstream such as increased erosion and flooding. Since the conventional stormwater facility on developed property is concerned with removing water as quickly as possible, it changes the hydrology of the site being developed (HolmanDodds et al. 2003). The increase in impervious surfaces reduces infiltration that would have occurred at a site, increasing the peak runoff that the receiving waters must handle, sometimes by multiple times as much over the natural runoff (Hood et al. 2007). Also, the stormwater runoff will carry suspended solids and pollutants from the site into the receiving water (Davis et al. 2009). For this reason, in recent years there has been significant study on establishing Low-Impact Development (LID) (Ahiablame et al. 2012; Davis and McCuen 2005), the goal of which is to mimic the natural hydrology of a site postdevelopment (Davis 2005) or to reduce pollutants entering waterbodies by altering the land use (Barfield et al. 2008). This is accomplished by promoting infiltration and detention, as well as removing pollutants when possible (Garrett 2007). Engineers and scientists are now collaborating to produce more-sustainable LID techniques such that the developed site will not affect runoff (Bedan and Clausen 2009) and watersheds are being restored using LID techniques (Guo 2010; Chang 2010). The purpose of the current work is to (1) briefly review issues involved in LID, (2) illuminate hydraulic issues that may lead to future modeling advances, and (3) encourage hydraulic engineers to lead in this rapidly developing field. Several LID techniques along with hydraulic issues that need addressed will be discussed next in an effort to encourage hydraulic engineers to participate in this rapidly-expanding field.