Penobscot Watershed Hydrology and History
Abstract
The Penobscot River Watershed has a long history of hydrologic alteration by humans. Dams, and the logging / mill industries that built them, have caused large changes to land use and surface water storage throughout the watershed. These modifications can influence the runoff and routing processes within the watershed, changing the timing and magnitude of downstream flows. Quantifying these changes to hydrologic regime, in the context of varied dam management, is our goal. We ask 1) how have dam management decisions altered hydrologic regime throughout the history of this watershed, 2) can changes in watershed characteristics be identified through comparison of simulated and measured discharge. We use three approaches to address these questions. First, we use hydrologic time-series to examine historical changes in the watershed by simulating flow regime with a hydrologic model of the Kingsbury Stream, and then compare simulated and measured discharge over a rolling time-window. Periods when the simulation differs from measurements suggest a change in watershed characteristics that is not represented in the model. Second, we compare hydrologic regimes across different periods in watershed history. This analysis utilizes USGS discharge measurements to examine changes in flow regime following changes in land and river use. Third, we take these measured and simulated discharges and use them to estimate stream power, river velocity, river depth, and other river conditions. These analyses inform the relationship between flow regime and dams in the Penobscot Watershed, and can provide new insight into water quantity trade-offs associated with dam management decisions.
