Thirty- and ninety-year data sets of streamflow, groundwater recharge, and snowfall simulating potential hydrologic response to climate change in the 21st century in New Hampshire

The U.S. Geological Survey (USGS), in cooperation with the New Hampshire Department of Environmental Services (NHDES) and the Department of Health and Human Services (NHDHHS), has developed tools to assess the effects of short- and long-term climate change on hydrology in New Hampshire. A USGS Scientific Investigations Report (SIR) report documents tools and datasets developed by the USGS to (1) predict how climate change will affect the hydrologic cycle and (2) provide tools and data that can be used by State and local agencies to identify locations that are vulnerable to the effects of climate change in areas across New Hampshire. Future hydrologic climate projections were developed from the output of five general circulation models (GCMs) for two greenhouse gas emission scenarios coupled with land-use and land-cover within a projected global economic framework. An evaluation of the possible effect of projected future temperature on modeling of evapotranspiration is summarized (and provided in an appendix) to address concerns regarding the implications of the future climate on model parameters that are based on climate variables. The hydrologic projections indicate increasing streamflow across the State with large increases in streamflow during DecemberMarch and general decreases during AprilAugust. Wide spatial variability in changes to groundwater recharge is projected, with general decreases in the Connecticut River Valley and at high elevations in the northern part of the State and general increases in coastal and lowland areas of the State. In general, total winter snowfall is projected to decrease across the State, but there is a possibility of increasing snow in some locations, particularly during November, February, and March. The simulated future changes in recharge and snowfall are predicted to vary by watershed across the State. This means that each area of the State could experience very different changes, depending on topography or other factors. Therefore, planning for infrastructure and public safety needs to be flexible in order to address the range of possible outcomes indicated by the various model simulations. The absolute magnitude and timing of the daily flows, especially the larger floods, are considered to be less reliably simulated compared to changes in frequency and duration of daily streamflows, and changes in accumulated monthly and seasonal flow volumes. Simulated current and future streamflow, groundwater recharge, and snowfall output datasets from the USGS Precipitation-Runoff Modeling System (PRMS) have been made available on-line in the USGS ScienceBase Web site. The datasets include simulated data derived from the five GCMs used in this study for a current reference time frame (1976-2005) and a future time frame (2010-2099). Average monthly streamflow time series data sets are provided for 21 streamgages in New Hampshire, 14 of which also provide daily streamflow time series, Average monthly groundwater recharge and snowfall time series for the same reference time frame and future time frame are also provided for each of the 467 hydrologic response units (HRUs) that compose the model.