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M a M l le k a K Nippo oo e r s 126 go J B ls a o c n e Pond ¬ « k y s C o Riv n er al ef B k Nippo Brook r o s o tle nco r Map Descroiption: Lit u e S k k n k o y o Lower ook o e Br o r r R B IsiBnglass River B Sp rook ru B B S t r a f f o r d ce ro B l S t r a f f o r d 9 o k a Cocheco River k Northwood B k th e ro «¬ or o This map illustrates the 100-year floodplain for the Watershed for three conditions: (1) the FEMA k Watershed ntw We Harvey Lake T

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c i Flood Insurance Rate Maps (Fe IRM) shown with blue cross hatching; (2) the current floodplain based on 2005 land k O B e 202A ig Lake d h r r k C t o n 9 o «¬ I n o H ok ro ¬ D « B E

use conditions and updated 100-year 24-hour rainfall of 8.5” shown in pink; and (3) the projected 2100 floodplain r C e O

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Map Key: Acreage Summary: 100-Year Floodplains: Residential/Commercial/Industrial Land Use: Technical Notes: Map Data Sources: Assessing Flood Risk in the Inundation Acreage within Area Mapped Total Acreage in Watershed The updated and projected floodplains were modeled using FEMA approved methodologies (watershed Updated 100-year floodplains: Data from NOAA/CICEET funded proposal ATERSHED hydrology using the US Army Corps of Engineers [USACE] Hydrologic Engineering Center Hydrologic "Assessing the Risk of 100-year Freshwater Floods in the Lamprey River W Updated (2005) 2100 Buildout Modeling System [HEC-HMS]; hydraulic analysis using the USACE Hydrologic Engineering Center River Watershed of Resulting from Changes in Climate and LOCATION Lamprey River Watershed Total Acreage Conditions (based on 11.4" rainfall) Updated 2100 Updated (2005) 100-Year Floodplains Limits of Inundation Mapping Analysis System [HEC-RAS]). The hydraulic model included 262 river cross sections: 115 sections from the Land Use", C. Wake, Principal Investigator. Acreage in within Area FIRM (based on 8.5" (2005) Buildout original FIS dataset, 46 sections from recent field survey and other analyses, 101 additional sections and Town Watershed Mapped 2005 rainfall) Conventional LID Conditions Conditions 2100 100-Year Floodplains: Lamprey River Watershed Boundary extended embankment elevations generated from 2011 LiDAR imagery (2-meter digital elevation model, 15- Effective Zones/Special Flood Hazard Areas: Effective DFIRM panels Barrington 4,344 0 ------332 1,877 cm vertical root mean square error). Reaches without surveyed cross-sections (Piscassic River and for Rockingham and Strafford Counties, May 17, 2005. Coos LID Buildout Brentwood 812 0 ------100 504 Moonlight Brook) used topography generated by LiDAR, and assumed channel geometry. Subwatershed Boundaries Surface Water: NH National Hydrography Dataset, April 2007. Effective Zone AE 100-Year Floodplains: Candia 11,917 16 6 8 11 10 1,237 7,845 The 100-year 24-hour rainfall depth for the period: (1) from 1938-2010 (8.5”) derived from the Northeast Special Flood Hazard Areas with Base Flood Lamprey River Deerfield 26,755 9 1 3 3 3 1,657 13,297 Regional Climate Center (http://www.precip.net); (2) up to 2100 (11.4”) derived from the largest 24-hour Watersheds: NH Department of Environmental Services, Durham* 4,984 802 499 567 625 621 667 2,160 rainfall event from downscaled model output from four global climate models. September 2002. Elevations (BFEs) determined Epping 16,752 2,495 899 923 1,026 1,019 2,082 10,523 River and Stream Networks Future land use extrapolated from 1962-2005 historical buildout rates, current zoning, and Conventional or Topography: National Elevation Dataset, 10-meter resolution Exeter 1,546 0 ------120 529 Low Impact Development. Grafton Effective Zone A 100-Year Floodplains: Digital Elevation Model. Carroll Town/County Bounds Fremont 2,999 7 ------531 1,951 Special Flood Hazard Areas with no The effective FIRM base flood elevations based on NAVD29 datum; the 2005, 2050, and 2100 base flood Lee 7,927 1,217 551 756 916 906 1,311 4,458 Transportation: NH Department of Transportation, April, 2010. Base Flood Elevations (BFEs) determined elevations based on the NAVD88 datum. State roads Newfields 2,612 50 28 24 26 26 329 1,204 Belknap While this map is not a legally binding document, federal and state guidance encourages the use of the most Sullivan Newmarket 6,559 1,904 450 641 741 732 1,701 4,203 Local roads current information available to support community-based planning and zoning. A detailed analysis of legal Northwood 7,549 0 ------621 4,998 issues associated with using this map (or others in this series), written by the Vermont Law School, is Merrimack Strafford Support for this project was provided by the Cooperative Institute Nottingham 30,681 0 ------2,109 12,691 available at the project web sites listed below. Legal FEMA effective Flood Insurance Rate Maps (FIRMs) Miles for Coastal and Estuarine Environmental Technologies (CICEET). Raymond 12,277 2,324 874 985 1,113 1,104 2,164 7,585 maps are available online at: http://www.granit.unh.edu/dfirms 0 0.25 0.5 1 1.5 2 Hillsborough Lamprey River Map produced June, 2012 Figures showing the surface water elevations and water discharge at each cross section Cheshire Rockingham Strafford 29 0 ------3 15 More project information and maps are available at: http://www.granit.unh.edu/MapLibrary/ProjectMaps or Watershed for each scenario can be viewed in a separate document available on the project web Scale: 1:40,000 Total Watershed* 137,743 8,822 3,309 3,907 4,461 4,423 14,965 73,838 http://100yearfloods.org Detailed methodology is also described in: Scholz, A. 2011. Consequences of For further information about this project, site: http://100yearfloods.org Changing Climate and Land Use to 100-Year Flooding in the Lamprey River Watershed of New Hampshire. (1 inch to 3,333 ft.) * Table includes acreage of flooding in bypass over the Oyster River in Durham. MS Civil Engineering, University of New Hampshire, Durham, NH. " please visit http://100yearfloods.org