Wetland Surface Water Processes
Abstract
The hydrologic and hydraulic (H&H) characteristics of a wetland influence all wetland functions and, consequently, should be an initial focus of a wetland evaluation. The processes by which water is introduced, temporarily stored, and removed from a wetland are commonly known as the water budget. Water is introduced to a wetland through direct precipitation, overland flow (or runoff), channel and overbank flow, groundwater discharge, and tidal flow. Temporary storage includes channel, overbank, basin, and groundwater storage. Water is removed from the wetland through evaporation, plant transpiration, channel, overland and tidal flow, and groundwater recharge. The relative importance of the above processes varies with wetland type (i.e. riverine, tidal, depressional), which depends on regional factors such as climate, geology, and physiography. In particular, the physiography or the topographic and bathymetric variation in and around a wetland affects the residence time within a wetland, which can either increase or reduce the relative impact of the H&H process. This technical note summarizes H&H processes and the related terminology that will likely be encountered during an evaluation of the effect of surface water processes on wetland function. The note provides general guidance to personnel in the field who lack specific expertise in H&H processes but are still faced with the regulatory responsibility of wetland permit evaluation. The following H&H processes are discussed: wetland basin characteristics, precipitation, evaporation and transpiration, channel and overbank flow, overland flow, groundwater recharge and discharge, and tidal and related flow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1993
- Accession Number
- ADA434515