Conversion Factors and Datum Multiply By To obtain Length inch (in.) 2.54 centimeter (cm) inch (in.) 25.4 millimeter (mm) foot (ft) 0.3048 meter (m) mile (mi) 1.609 kilometer (km) Area square mile (mi 2) 2.590 square kilometer (km 2) Flow rate cubic foot per second (ft 3 /s) 0.02832 cubic meter per second (m 3 /s) Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

This report presents regression equations to estimate generalized annual and seasonal groundwater recharge rates in drainage basins in New Hampshire. The ultimate source of water for a groundwater withdrawal is aquifer recharge from a combination of precipitation on the aquifer, groundwater flow from upland basin areas, and infiltration from streambeds to the aquifer. An assessment of groundwater availability in a basin requires that recharge rates be estimated under 'normal' conditions and under assumed drought conditions. Recharge equations were developed by analyzing streamflow, basin characteristics, and precipitation at 55 unregulated May 31) groundwater recharge was 9.0 in., average summer (June 1-October 31) groundwater recharge was 4.0 in., and average fall (November 1-December 31) groundwater recharge was 3.6 in. Normalized groundwater recharge ranged annually from 12.3 to 31.8 in., for winter from 2.30 to 7.82 in., for spring from 5.16 to 13.7 in., for summer from 1.45 to 10.2 in., and for fall from 2.21 to 6.06 in. Description of Study Area New Hampshire encompasses an area of 8,973 mi 2 of which 309 mi 2 is water (New Hampshire State Data Center, 2001) (fig. 1). The State is in the Seaboard Lowland, New England Upland, and White Mountain sections of the New England Physiographic Province (Fenneman, 1938). The southeastern part of the State primarily is coastal plain, the central region primarily is lowland and foothills, and the northern part primarily is mountainous. The elevation and amount of topographic relief gradually increase from south to north. Precipitation ranges from an annual mean of about 35 in. in the Connecticut and Merrimack River valleys to about 90 in. on the summit of Mt. Washington (Hammond, 1989). Typically, statewide, the driest month is February. The wettest months are November and December in the area south of the White Mountains, and June, July, and August in the area north of the White Mountains (Hammond, 1989). Average runoff ranges from 18 in/yr in parts of the Connecticut River Valley and seacoast area to about 42 in/yr in the White Mountains. Streamflow varies both seasonally and geographically. High flows typically occur during

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. AcknowledgmentsThe author would like to express appreciation to the following U.S. Geological Survey personnel who assisted with collection of data in this report-Richard Kiah, Scott Olson, Thor Smith, James Degnan, Chandlee Keirstead, Heather Manzi, and Glenn Berwick.The author would like to acknowledge that the cost of generating the 1-and 4-ft contour interval data used in the creation of the flood mapping for this study was funded through a New Hampshire Department of Safety-Bureau of Emergency Management grant (Emergency Management Performance Grant) with in-kind matching funding provided by the New Hampshire Department of Environmental Services through its dam-maintenance efforts in the Suncook River watershed. AbstractOn May 15, 2006, a breach in the riverbank caused an avulsion in the Suncook River in Epsom, NH. The breach in the riverbank and subsequent avulsion changed the established flood zones along the Suncook River; therefore, a new flood study was needed to reflect this change and aid in flood recovery and restoration. For this flood study, the hydrologic and hydraulic analyses for the Suncook River were conducted by the U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency.This report presents water-surface elevations and profiles determined using the U.S. Army Corps of Engineers onedimensional Hydrologic Engineering Center River Analysis System model, also known as HEC-RAS. Steady-state watersurface profiles were developed for the Suncook River from its confluence with the Merrimack River in the Village of Suncook (in Allenstown and Pembroke, NH) to the upstream corporate limit of the town of Epsom, NH (approximately 15.9 river miles). Floods of magnitudes that are expected to be equaled or exceeded once on the average during any 2-, 5-, 10-, 25-, 50-, 100-, or 500-year period (recurrence interval) were modeled using HEC-RAS. These flood events are referred to as the 2-, 5-, 10-, 25-, 50-, 100-, and 500-year floods and have a 50-, 20-, 10-, 4-, 2-, 1-, and 0.2-percent chance, respectively, of being equaled or exceeded during any year. The 10-, 50-, 100-, and 500-year flood events are important for flood-plain management, determination of floodinsurance rates, and design of structures such as bridges and culverts. The analyses in this study reflect flooding potentials...

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://store.usgs.gov.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Flynn, R.H., and Hayes, Laura, 2016, Flood-inundation maps for Lake Champlain in Vermont and in northern Clinton County, New York: U.S. Geological Survey Scientific Investigations Report 2016-5060, 11 p., http://dx.doi.org/10.3133/sir20165060.

The Milford-Souhegan glacial-drift (MSGD) aquifer, in southcentral New Hampshire, is an important source of water for industrial, commercial, and domestic use that provides more than 2.7 million gallons of water per day in 1994. A large plume of volatile-organic compounds (approximately 0.5 square miles in area) covers a large part of the western half of the MSGD aquifer and threatens existing groundwater usage. The plume area has been designated a superfund site and named after a former municipal water-supply well (Savage Well) that was discontinued because of contamination. A 3-year study by the U.S. Geological Survey and the U.S. Environmental Protection Agency began in January 1994 to examine the temporal variability of groundwater flow in the contaminant plume and adjacent areas of the western half of the MSGD aquifer. This report summarizes construction and evaluation of threedimensional, steady state and transient numerical groundwater flow models that will be used to help design a remediation plan for containing volatile organic contaminants. The results of the steady-state simulation of average-flow conditions from June 1994 to June 1995 show a close comparison between modelcomputed heads and observed heads at more than 70 wells. Most heads are within 1.5 feet of observed heads. The standard-mean-head error is-0.12 feet, indicating that computed heads are slightly lower than observed heads. The absolutemean-head error is 0.59 feet, and the root-meansquare error is 0.89 feet. The results of the transient model of seasonal-flow conditions also show a close comparison between computed-head fluctuations and observed-head fluctuations for the same wells. The largest difference in computed and observed heads occurs for the fall of 1994 (standard-mean-head error of 0.29 feet). Computed variations in direction and slope of maximum hydraulic gradients compare well with observed variations for most areas of the model. The analysis, however, identified several areas of the model where further testing is suggested. These areas include those (1) near the source area of contaminants, (2) in the northcentral part of the plume, and (3) at the northern leading edge of contaminants near the confluence of two rivers.