Modeling the flood modification effects of a mid-sized unregulated wetland

In contrast to the extensive literature on hydrologic modeling of agricultural and urban land classes, relatively little attention has been focused on the prediction of the stormflow response from wetland ecosystems. If required to predict the rate of outflow from a wetland system, the hydrologist or engineer has few numerical tools and little available data to assist in the prediction. This chapter presents the application of a numerical wetland model using synthetic precipitation events. The wetland model consists of a field hydrology model fully coupled to a stream routing model. The field hydrology model incorporates two distinct layers, one representing the surficial hummock terrain common to many wetlands and the other representing the organic layer characteristic of all wetland sites. The hydrology model includes process representations for the quickflow responses associated with overland flows through the surficial hummock terrain and long-term subsurface interflow mechanisms within the wetland organics. Antecedent saturation states dictate the amount of storage available for temporarily storing meteorologic inputs. Under low saturation levels, the stormflow response is controlled by subsurface stormflow mechanisms, Under high saturation levels, overland flow mechanisms shape the response. Over the past few years, the integration of wetland sites and adjacent urban land use has been a focus of discussion. The results of this study illustrate the complexity and variability of the hydrologic response at a wetland site, even to a single precipitation input.