Water Resources Research Act Program

Details for Project ID 2009NY116B

Silica dynamics and nutrient retention modeling in the Hudson River Watershed

Institute: New York
Year Established: 2009 Start Date: 2009-03-01 End Date: 2010-02-28
Total Federal Funds: $20,000 Total Non-Federal Funds: $40,047

Principal Investigators: Robert Howarth, Dennis Swaney

Abstract: The Hudson watershed is subject to changes in land use and climate which affect nutrient levels and trophic status of its waters, but the details of controls on nutrient loads to its river reaches and estuary are complex. Biogeochemical processes are complicated by regional interactions of nutrients, including nitrogen (N), phosphorus (P) and silica (Si), in watershed streams and its estuary. Understanding how these processes affect the magnitude and transformations of the nutrient loads is necessary to manage the environmental resources of the region. It is important for those living in the watershed to understand the impacts of their activities and policies on these nutrient loads. Modeling tools that integrate the patterns of nutrient sources, landscape, and in-stream processes can improve our ability to manage and communicate the effects of human activities and environmental processes on nutrient loads. While excess N and P are typically held responsible for eutrophication problems, a recent report of the National Academy of Science’s Committee on Causes and Management of Coastal Eutrophication noted the importance of Si delivery to estuaries, and the implications of Si limitation in the frequency of harmful algal blooms (HABs) (29). Given the Hudson’s comparatively low levels of Si (36) and the known relationships between dams and Si depletion in rivers (21) improving knowledge of Si dynamics in the Hudson watershed should be a priority. Using existing information on Si, we propose to modify the Regional Nutrient Management model (ReNuMa), which has been developed previously as a watershed management tool, to address the priorities of improving estimates of nutrient retention and likelihood of HAB occurrence in the waters of the Hudson/Mohawk.