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Evaluating the aggregate effect of geographical isolated wetlands and associated spatial and size distributions on downstream hydrologic flows
Citation:
Evenson, G., H. Golden, AND C. Lane. Evaluating the aggregate effect of geographical isolated wetlands and associated spatial and size distributions on downstream hydrologic flows. Joint Aquatic Sciences Meeting 2014, Portland, OR, May 18 - 23, 2014.
Impact/Purpose:
Present research on the aggregated effects of geographically isolated wetlands at the Joint Aquatic Sciences Meeting, May 18-23, 2014 in Portland, Oregon.
Description:
Geographically isolated wetlands (GIW), defined as depressional wetlands completely surrounded by uplands, support an array of ecological processes. A solid scientific understanding of the hydrologic effects of GIWs upon downstream waterways is important for legal and policy-making decisions in the USA. To date, however, few examples exist of simulation frameworks that explicitly address this relationship. In this study we are incorporating wetland spatial data and estimated storage volumes within the Soil and Water Assessment Tool (SWAT) to discern the aggregate effect of GIWs on streamflow. We propose a new method of defining hydrologic response units (HRU), the basic units of hydrologic simulation within SWAT, to incorporate a binary attribute indicating the HRUs existence within calculated GIW drainage areas to provide a more accurate representation of GIW hydrologic effects. We construct a base model for our 207 km2 study area in the Coastal Plain of North Carolina, USA, calibrated without representation of the storage effects of the study area’s wetlands. We then evaluate a series of scenarios that iteratively incorporate GIWs and non-isolated wetlands within the model to evaluate the relative hydrologic effect of their additions. Finally, we evaluate a series of model scenarios within which only GIWs exhibiting particular size or spatial characteristics are added to the base model to evaluate the effects of alternative spatial and size distributions. The results of this study will increase our understanding of the degree of influence that GIWs exhibit upon other waterways.