Evaluation of Stream Temperature Response in the Connecticut River to Climate Change, Riparian Logging and Reservoir-induced Hydrologic Alteration

Abstract:

Water temperature and streamflow play a critical role in the function of aquatic ecosystems. In the Connecticut River, the hydrologic and thermal regimes have been significantly altered by dams and impoundments as well as by changes in land use that include timber harvest and the clearing of land for agriculture. The impact of these alterations is expected to be more pronounced under projected climate change. We apply a spatially distributed hydrology-stream temperature modeling system, DHSVM-RBM, to evaluate the hydrologic and stream temperature changes associated with climate change, disturbance of riparian vegetation, and removal of reservoirs and impoundments. We configured DHSVM-RBM for 14 major basins in the Connecticut River Basin at a spatial resolution of 150 m and a sub-daily timescale. For existing conditions, characterized by 65 major reservoirs in the main stem of the Connecticut River, we simulated streamflows and temperatures and compared results with flow gage observations and stream temperature measurements. We then explored the relative impact of climate change, disturbance of riparian vegetation, and removal of dams/reservoirs on streamflow and water temperature variations in the Connecticut River in a spatially explicit manner at sub-daily, seasonal and inter-annual time scales. The findings will provide stakeholders with guidance regarding strategies for adapting to future climate change.