Date of Award

12-2019

Document Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Ellen Douglas

Second Advisor

Crystal Schaaf

Third Advisor

Julie Dyer Wood

Abstract

Water quality in the Upper and Middle Charles River Watershed has improved over the past several decades primarily due to improvements statewide in wastewater management. However, climate change threatens this progress, with future projections promising increased precipitation and temperatures for the New England region. This study investigated the impact of climate change projections on total phosphorus loads in the Upper and Middle Charles River Watershed using the HSPF model. Model input data were extended through 2018 to update present day conditions represented by the previously calibrated and validated HSPF model. The updated model was then used to simulate the following scenarios: present day climate conditions and future climate change conditions assuming high greenhouse gas emission or low greenhouse gas emission. For each scenario, total phosphorus loads were calculated by town and compared to phosphorus load reduction goals specified in the US EPA Municipal Separate Storm Sewer System permit.

Generally, an increase in total phosphorus loads was observed in future scenarios when compared to present day conditions. Increased precipitation had the greatest impact on phosphorus loads throughout the watershed. Overall, a decrease in loads from almost all towns within the upper and middle watershed would be needed in order to meet the required water quality targets for phosphorus in most scenarios. This study serves as an indication of possible future upward trends in phosphorus loads to be expected from towns in the Upper and Middle Charles River Watershed and recommends that projected climate change impacts on phosphorus loads be considered when towns implement phosphorus management and mitigation plans.

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