This project evaluates the costs and benefits of floodplain protection in Waterbury, Vermont and Willsboro, New York in the Lake Champlain Basin, U.S.A. The primary elements of the project are ecosystem service valuation, buildout/conservation analysis, hydrologic calculations of current existing peak flows and predicted future peak flows, hydraulic modeling of floodplains, building damage simulations due to flooding, and a cost‐benefit accounting to determine what form of flood risk reduction makes sound economic sense.
The participating towns, and many others in the region, have endured damaging floods in the past few years due to their riverine and lakeshore setting. The towns are now grappling with difficult decisions to improve economic opportunities while increasing flood resiliency. Where and to what level does floodplain protection make sense? Do the benefits of floodplain protection (i.e., reduction of flood damages, lower recovery costs, increased health and safety, enhanced ecosystem services) outweigh the costs (i.e., loss of economic opportunity, reduced tax base, project implementation costs, increased building costs to flood‐proof structures, and recovery of structures remaining in the floodplain)? The results of this study will provide important information to towns in the Lake Champlain region to make sensible floodplain management decisions.
The technical content of this project is a collaboration between Milone & MacBroom of Waterbury, Vermont, Fitzgerald Environmental of Colchester, Vermont, Earth Economics of Tacoma, Washington, and dkcarlton & associates of Lake Forest Park, Washington. The project was led by the Lake Champlain Basin Program, and was supported by funds awarded to the New England Interstate Water Pollution Control Commission by the U.S. Environmental Protection Agency.
The benefit transfer analysis method was used to estimate the economic value of a given ecosystem from prior studies of that ecosystem type. Research was performed to expand the Earth Economics database to cover the Lake Champlain region and the Earth Economics Ecosystem Valuation Tool Kit was used to value floodplain function. The research and analysis resulted in a range of $/acre/year for six land cover classes in the floodplain (agriculture, forest, shrubland/grassland, wetland, river, and village greenspace).
Each of the Towns in this study has a large base value of ecosystem services over a 50‐year timeframe ‐ $38.1 million to $216.3 million in Waterbury, Vermont and $4.5 million to $37.0 million in Willsboro, New York. This often unaccounted for value for services such as erosion control, flood mitigation, and recreation and tourism should be protected and expanded where possible. More services are provided when buildings are removed, while less take place upon building and land use conversion away from naturally functioning land.
Meetings were held with each Town to select floodplain management areas and scenarios for this study. The valley bottom floodplain settings and low‐gradient river channels lead to flooding as the primary hazard, and thus modeled inundation‐based floodplains are suitable management areas at both project sites. The management scenarios include existing conditions, building elevations, utility elevations, building removals, and buildout (full floodplain buildout following current floodplain regulations, removing all buildings in the 100‐year floodplain, and removing the most floodprone buildings). Flood risk reduction alternatives were identified for each Town and inserted into the hydraulic model. A preferred alternative that lowered flood levels the most and was supported by the Town was
selected for damage modeling.