STORMWATER AND TIDAL HYDRAULICS IN AN URBAN COASTAL WATERSHED: LAND USE CHANGE IMPACTS
Loading...
Date
Authors
Kuhl, Hannah
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
This study developed a water balance method for a suburban tidal creek watershed located in Charleston, South Carolina. The major objectives were to separate the relative functions and dynamics of tidal flows and stormwater runoff for James Island (JI) Creek at two spatial scales, and to characterize the vegetation of selected sub-watersheds in this suburban landscape. Stormwater runoff modeling provided estimates of runoff volumes entering the creek system during storm events and responses were compared across levels of development in the sub-watersheds. Stormwater runoff modeling showed a linear, positive relationship between runoff ratios and percent impervious cover, as expected based on previous studies. Stormwater runoff exceeded tidal volume with about 107 mm of rain in a first order watershed and about 165 mm of rain in a second order watershed. Observations of marsh vegetation on a sub-watershed scale allowed for detailed mapping of vegetation in one area, and identified one sub-watershed where runoff may have contributed to marsh die-off. Discharge and channel geometry were measured under a variety of tidal conditions and compared to four previously studied tidal creeks in the region. The relationship of time and discharge for JI Creek was fit to a sine curve. The power functions of previously developed hydraulic geometry curves remained the same when JI Creek was added, confirming the consistency of these mathematical relationships for this region. Identifying locations or events of high stormwater delivery can inform scientists and managers about problem areas in urbanized tidal creek systems. The combination of tidal volume measurements and stormwater runoff modeling provides valuable information concerning the threshold for when stormwater runoff volume will begin to surpass tidal creek volume and allows for impacts from drastic salinity shifts and various pollutant loads to be considered.