Hydrologic budget for a wetland system.

40063433Final Report, August 1996-June 1998PDFResearch Paperhttp://ntl.bts.gov/lib/21000/21000/21075/PB98173875.pdfVTRC-99-R9SPR 5759-030-940WetlandsHydrologic cycleVirginiaVirginia Transportation Research CouncilYu, S. L.Fassman, E. A.Virginia. Dept. of TransportationUnited States. Federal Highway AdministrationNTL-ENERGY AND ENVIRONMENT-ENERGY AND ENVIRONMENTNTL-ENERGY AND ENVIRONMENT-Maritime Energy and EnvironmentUS Transportation CollectionAn important functional indicator of the success of a constructed wetland as a replacement for a natural system is the hydrology ofa site and whether it is adequate to support wetland vegetation and habitats. For constructed wetlands with potentially limitinghydrologic conditions, such as sites that rely on stormwater runoff as the primary source of water, particular attention to water lossthrough evapotranspiration (ET) is necessary in determining the water balance. The literature reveals a variety of techniques used tocalculate ET and demonstrates the difficulty in estimating ET. Of the methods presented in this report, three empirical relationshipswere applied to the water balance of a stormwater-supported mitigated wetland. The results were compared to those given by directmeasurement.Empirical estimation of wetland ETrevealed that the Penman method most closely reflected actual wetland ET, the Thornthwaitemethod predicted water loss at a rate significantly less than the actual rate, and restrictions of the Class A pan evaporation methodrendered the method inappropriate for the given conditions. The accuracy of any empirical estimator to reflect ET rates may improvefrom on-site data collection of climate parameters