Assessing the Risk of 100-year Freshwater Floods in the Lamprey River Watershed of New Hampshire Resulting from Climate Change and Land Use

Created: 3/29/2010 - Updated: 12/03/2021

Summary

The Great Bay National Estuarine Research Reserve, the University of New Hampshire, and Antioch University New England worked to improve information regarding flood risk in the Lamprey River Watershed in New Hampshire. This project developed a methodology for assessing flood risks and, based on future land use and climate change scenarios, provides decision-makers, planners, and the public with products to support land-use decision-making.

Background

The Great Bay Estuary is one of the largest on the Atlantic Coast and is located nearly 10 miles inland. One of the many rivers that drain into the estuary is the Lamprey River, which originates in the Saddleback Mountains and flows 47 miles to its mouth at the estuary. The Lamprey River Watershed drains approximately 212 square miles. The primary towns in the watershed are Candia, Deerfield, Durham, Epping, Lee, Northwood, Nottingham, Newmarket, and Raymond. Major flood events in October 2005, May 2006, April 2007, and March 2010 caused infrastructure damage and habitat degradation. Other stressors to the system include development pressures and climate change impacts, such as sea-level rise, precipitation changes, flooding, erosion, increased storms, and landslides. Development and land-use change combined with climate change effects can affect flood events in both magnitude and frequency.

Researchers from the University of New Hampshire and Geosyntec Consultants developed and refined a methodology for assessing flood risks to the Lamprey River Watershed associated with land use and climate change scenarios.

Implementation

The initial project was funded by the Cooperative Institute for Coastal and Estuarine Environmental Technology (CICEET); subsequent funding was obtained from the National Sea Grant Law Center and New Hampshire Sea Grant. Scientists assessed flood risks under different urban growth/land use and climate change scenarios (greenhouse gas emissions, sea-level rise, temperature fluctuations, precipitation levels). The main products included municipal-scale maps of the 100-year flood risk boundaries and river discharge at specific locations in the watershed. The project also involved an education component, including fact sheets, videos, and a website where the public, local policymakers, and planners can learn more about 100-year flood events, how climate and land use affect flooding, and what actions can be taken.

Outcomes and Conclusions

In the Lamprey River Watershed, decision-makers, planners, and the public now have access to new information on the physical and economic impacts of flood risk based on future land use patterns and climate change scenarios.

Resources:
Assessing Flood Risk in the Lamprey River Watershed
New Hampshire Statewide GIS Clearinghouse: Project Details 
Lamprey River Watershed Generalized Land Use Maps

Status

Information gathered from interviews and online resources. Last updated on 8/21.

Citation

Gregg, R. M. (2020). Assessing the Risk of 100-year Freshwater Floods in the Lamprey River Watershed of New Hampshire Resulting from Climate Change and Land Use [Case study on a project of the Great Bay National Estuarine Research Reserve, University of New Hampshire, and Antioch University New England]. Product of EcoAdapt's State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/assessing-risk-100-year-freshwater-floods-lamprey-river-watershed-new-hampshire-resulting-climate-change-and-land-use (Last updated July 2020)

Project Contact(s)

The New Hampshire Fish and Game Department under the Marine Fisheries Division manages the Great Bay NERR. Designated in 1989, the Reserve's primary purpose is to promote the wise use and management of the Great Bay Estuary. Encompassing over 25,000 acres of tidal waters and uplands, the Reserve is part of the Atlantic flyway and located in the Arcadian bioregion.

Antioch University New England (AUNE) is a dynamic, innovative institution offering scholarly, practice-oriented graduate study. Now in its forty-fifth year, AUNE serves 1,000 students and remains, by design, a small graduate school closely linked to the region, with national and global connections through its students, alumni, and institutional concerns.

Related Resources

Adaptation Phase
Awareness
Assessment
Planning
Implementation
Integration/Mainstream
Evaluation
Sharing Lessons
Sector Addressed
Biodiversity
Climate Justice
Conservation / Restoration
Culture/communities
Disaster Risk Management
Education / Outreach
Fisheries
Land Use Planning
Policy
Research
Rural / Indigenous Livelihoods
Transportation / Infrastructure
Water Resources
Wildlife
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