Paving the way to better stormwater management: water quality, porous pavement, and public policy
Dreelin, Erin Anne
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Urbanization is a pervasive threat to stream ecosystems. I examined the effects of urbanization on watershed hydrology and explored ways in which to reduce those negative impacts. The Etowah River basin (Georgia, USA) showed evidence of hydrologic alteration due to urbanization even at low levels (3-15%) of urban land use. Peak flows have increased and pollutant concentrations have increased significantly over time. Because the increase in stormwater runoff is causing measurable effects in Georgia streams, I tested the viability of using porous pavements for stormwater management on the fine-grained soils of the Piedmont. Monitoring of a full-scale grassy porous pavement parking lot demonstrated a 93% reduction in the volume of runoff and a significant decrease in turbidity of runoff for the porous lot vs. a nearby asphalt lot. A field experiment further supported these findings; concrete porous pavers were also effective in reducing the volume of runoff as well as nutrient and total suspended solids loads when compared to concrete controls. Porous pavements are an effective stormwater management practice for small storm events (< 2.64 cm). However, the use of porous pavements and other innovative stormwater management techniques are often prohibited or discouraged by local government regulations. Evaluation of zoning and subdivision regulations across the Etowah River Basin identified areas that require revision in order to implement low impact development techniques. Working with an interdisciplinary group of researchers, I developed management tools, site design guidelines and a model stormwater management ordinance, that encouraged the use of source controls for stormwater. This was a drastic departure from the traditional collection and conveyance approach common in the Etowah River basin. The management tools are intended to reduce the degradation caused by impervious surfaces by preserving or mimicking natural watershed hydrology.