Dams, nutrients, and water quality: A study of time-explicit reservoir ecological functions in the Chesapeake Bay Watershed
Abstract
River damming has been practiced for millenia to provide irrigation for agriculture, to prevent downstream flooding, and to generate both mechanical and electrical power. The reservoirs behind these dams impede water flow and increase residence times along the land-ocean aquatic continuum, leading them to act as sediment traps and in-stream reactors for nutrients. The Chesapeake Bay Watershed is home to more than 1475 dams and reservoirs, from small mill dams to the large Conowingo Dam and Reservoir on the lower Susquehanna River. But despite both the regional and global importance of reservoirs to water quality and aquatic ecosystems, we continue to have a limited understanding of how these hydrologic structures impact the sink and flow of legacy contaminants, and of how these effects may change under future scenarios, including a warming climate, aging infrastructure, and dam removal. (1) In this work, we address the need for more comprehensive reservoir datasets by presenting an open-source geo-referenced database of dams to date in the Chesapeake Bay region, containing their location and other associated information (surface area, storage, drainage watershed, residence time, discharge, N inputs, and dam orders) (2) We use both data synthesis and process-based modeling approach to quantify the time-varying effects of reservoirs on riverine N loading across the Chesapeake Bay Watershed, and to explore the long-term implications of these on the achievement of the water quality goal, the Chesapeake Bay total maximum daily load (TMDL). Our preliminary work suggests that water residence times vary considerably for these reservoirs, from days to nearly a year, as a function of both reservoir size and river discharge magnitudes to the individual water bodies, and their corresponding nutrient retention functions continue to change under different future scenarios.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H16B..02C