Both the Fourth National Climate Assessment (NCA) and the IPCC Fifth Assessment Report (AR5) conclude that climate change will have major impacts on the hydrology of rivers, and these impacts, in turn, will directly affect the health of aquatic ecosystems by changing the characteristics of “aquatic flows.” The term “aquatic flows” for this presentation is defined simply as hydrologic flow regimes that are suitable for providing habitat for aquatic systems and ecosystem services. Healthy aquatic ecosystems can be negatively impacted by extreme hydrology events such as floods and droughts. Due to climate change, extreme precipitation in much of the US (99th Percentile Precipitation) is forecasted to increase by as much as 40%. Likewise, future droughts in most of the US are forecasted to be “stronger and potentially last longer.” Extreme floods and droughts will impose significant impacts to natural systems. In addition to these climate change impacts, aquatic flows are also signficantly impacted by other agents, including water withdrawals, hydropower production, changes in landcover, and urbanization.
This presentation will begin by reviewing changes in snowpack, streamflows and extreme hydrologic events that are projected by global circulation and hydrological models in the northeast. Next, it will summarize the history of management responses to anthropogenic impacts on aquatic flows. It will also explore ways in which changes in aquatic flows have been measured and the challenges encountered when evaluating the impacts of changes on the services provided by aquatic ecosystems. Finally, it will conclude with a description of a new, multi-year research effort that will engage the national network of Climate Adaptation Science Centers (CASC), USGS Research Centers, and relevant stakeholders. This project, termed the “Future of Aquatic Flows,” is in its early stages and will be conducted over the next three years.