Hydrological extremes across the Commonwealth of Massachusetts in a changing climate

Abstract

Study region: The Commonwealth of Massachusetts, United States. Study focus: The Commonwealth of Massachusetts is projected to experience significant impacts from future climate change and these impacts include but are not limited to increases in extreme precipitation, flooding and droughts. This study investigates the potential impacts of climate change and uncertainties on future floods and low flow conditions in the rivers and streams of Massachusetts. Fourteen downscaled GCM projections under two greenhouse gas concentration pathways (RCP4.5 and RCP8.5) are used as inputs into a distributed hydrological model to obtain future streamflow conditions. New hydrological insights for the region: Seasonal change projections of 100-year flood and a measure of drought (the seven-day, ten-year low flow - Q7,10) are estimated through the near-term (years 2021−2060) and the far-term (years 2060−2099) relative to the base period (years 1981–2016). The median estimates of 100-year flood during winter report a 15 % or higher increases in many watersheds at the far-term. In contrast, flood magnitudes in spring show decreases for most of the watersheds during both near- and far-term. For seven-day, ten-year low flow estimates, largest decreases are projected during the fall and this trend is found to be consistent across future time periods. Two emission scenarios have shown similar trends for most cases although change projections are seen to be more prominent for RCP8.5 when compared to RCP4.5.

Keywords

• Climate change
• GCMs
• Hydrological modeling
• 100-year floods
• Low flows