Methods for Estimating Withdrawal and Return Flow by Census Block for 2005 and 2020 for New Hampshire

The U.S. Geological Survey, in cooperation with the New Hampshire Department of Environmental Services, estimated the amount of water demand, consumptive use, withdrawal, and return flow for each U.S. Census block in New Hampshire for the years 2005 (current) and 2020. Estimates of domestic, commercial, industrial, irrigation, and other nondomestic water use were derived through the use and innovative integration of several State and Federal databases, and by use of previously developed techniques.

The New Hampshire Water Demand database was created as part of this study to store and integrate State of New Hampshire data central to the project. Within the New Hampshire Water Demand database, a lookup table was created to link the State databases and identify water users common to more than one database. The lookup table also allowed identification of withdrawal and return-flow locations of registered and unregistered commercial, industrial, agricultural, and other nondomestic users. Geographic information system data from the State were used in combination with U.S. Census Bureau spatial data to locate and quantify withdrawals and return flow for domestic users in each census block.

Analyzing and processing the most recently available data resulted in census-block estimations of 2005 water use. Applying population projections developed by the State to the data sets enabled projection of water use for the year
2020. The results for each census block are stored in the New Hampshire Water Demand database and may be aggregated to larger political areas or watersheds to assess relative hydrologic stress on the basis of current and potential water availability.