DES, Town of Raymond and SNHPC Collaborate to Consider River Erosion Hazard Ordinance Zoning
Concord, NH – The New Hampshire Department of Environmental Services (DES), the Town of Raymond Planning Board and the Southern New Hampshire Planning Commission (SNHPC) are working together to develop new zoning ordinances using recently mapped fluvial (river) erosion hazard zones.
Subsequent to the major flood events New Hampshire experienced from 2005 to 2007, DES has embarked upon a river assessment program to allow identification of lands adjacent to rivers that are most susceptible to erosion damage from rivers during high water events. The damage frequently takes the form of streambank failures, directly impacting properties and infrastructure located too close to a river. River scientists have developed tools that allow river segments to be field assessed so that areas particularly susceptible to fluvial (river) erosion damage can be determined and mapped. These mapped areas are called fluvial erosion hazard zones.
This river assessment program was piloted in New Hampshire last year in the Exeter River watershed. The Exeter River assessment delineated areas adjacent to reaches of Fordway Brook and the Exeter River in Raymond where the potential risks from these fluvial (river) erosion events have been identified. “New Hampshire experienced devastating floods over the past five years and many communities sustained catastrophic losses. The Exeter River assessment provides science and tools to help municipalities and river managers protect investments in the river corridor,” according to Sally Soule, DES’s project manager for the Exeter River assessment.
The Town of Raymond Planning Board is now using this information to consider the possibility of a fluvial erosion hazard zoning ordinance that would apply in those areas that have been delineated through the river assessment process. They are being assisted by the Southern New Hampshire Planning Commission (SNHPC) through the use of American Recovery and Reinvestment Act funds in their outreach and ordinance efforts. Personnel from the Watershed Management Bureau and New Hampshire Geological Survey have been working with both Raymond and SNHPC to provide the technical knowledge on understanding river processes and the assessment tools used in creating the fluvial erosion hazard zones.
Based on the success of the Exeter watershed project, the river assessments and fluvial erosion hazard program will be continuing and expanding through the New Hampshire Geological Survey at DES. “We are presently completing assessments on the Ammonoosuc and Isinglass Rivers this fall. Next year, we are planning to assess about 120 miles throughout the Lamprey and Cocheco watersheds,” said Shane Csiki, Fluvial Geomorphology Specialist in NHGS at DES.
In the future, as more rivers are assessed, and towns consider using this information for planning purposes, DES will continue to provide technical assistance to regional planning commissions and communities as they apply the information gained through these projects.For more information about the efforts in Raymond, please contact Sally Soule, DES Coastal Watershed Supervisor at (603) 559-0032, or via e-mail at [email protected]. For more information about the state’s river assessment and fluvial erosion hazard program, please contact Shane Csiki, DES/NHGS Fluvial Geomorphology Specialist at (603) 271-2876, or via e-mail at [email protected].
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