Historical Trends in Summer Precipitation, Baseflows, and Stormflows in New England and Projections of Seasonal Streamflows for Coastal Streams in Maine

USGS has documented historical trends (1950-2006) toward increasing summer precipitation, baseflows, and stormflows for unregulated streams in much of New England. Increases were large (>20%) in many places, and very large (>50%) at some streams in NH and VT. Some decreases in baseflows were documented in coastal and northern Maine where increased air temperature and evapotranspiration may have played a role. Calibrated watershed models for 4 coastal rivers in Maine were used to simulate future hydrologic conditions and streamflows in the watersheds over the next century. Precipitation and air temperature input to the models were from 5 General Circulation Models (GCMs) from the World Climate Research Programme's Coupled Model Intercomparison Project phase 3 multi-model dataset archive. The models indicate warmer winter conditions leading to increased winter snowmelt and rain-on-snow precipitation which causes higher winter streamflow and lower spring streamflow.