Evaluation of River Management Impacts on Riparian Wetland Functions Using the Wetland Hydrologic Index

The Wetland Hydrologic Index (WHI) presented in this paper is a tool to evaluate relative impacts of river management scenarios on riparian wetland functions. WHI are calculated using matrix summaries of monthly stage exceedence frequencies for reference and alternative water management conditions and the elevation distribution of riparian wetland acreage. In a manner similar to the Habitat Suitability Index developed by the U.S. Fish and Wildlife Service, WHI are multiplied by wetland acreage to calculate the Wetland Hydrologic Unit (WHU). Comparisons of the WHI matrices and WHU for various scenarios allows river managers to rank scenarios for relative degree of impact to riparian wetland functions and to evaluate the impacts in terms of depth, duration, and season of inundation for affected wetland acreage.