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Beaver Impact on Pre-Colonial Hydrology and River Morphology in Northeastern Connecticut
EPA Grant Number: F07E10815Title: Beaver Impact on Pre-Colonial Hydrology and River Morphology in Northeastern Connecticut
Investigators: Burchsted, Denise
Institution: University of Connecticut
EPA Project Officer: Boddie, Georgette
Project Period: January 1, 2007 through January 1, 2010
RFA: STAR Graduate Fellowships (2007)
Research Category: Academic Fellowships , Aquatic Ecology and Ecosystems , Fellowship - Water and Watersheds , Fellowship - Ecological Restoration , Fellowship - Aquatic Ecology
Description:
Objective:Billions of dollars are being spent across the US on river restoration projects, intended to return "an ecosystem to a close approximation of its condition prior to disturbance.” However, our understanding of the pre-disturbance system is often limited, and is typically based on “reference” rivers that are highly altered by recent and/or modern human activity. The absence of known fluvial baselines is notable in Connecticut, where European settlement and landscape alteration preceded serious examination of the river systems. Of the many variations in the modern reference system from the baseline condition, pre-colonial dominance of beaver – an “ecological engineer” - has been identified as a significant quantifiable difference. Therefore, the goal of the proposed research is to begin quantification of baseline fluvial conditions, focusing on ecologically-significant hydrologic flows and morphology prior to European colonization. Detailed efforts will quantify the hydrologic and morphologic impact of pre-colonial beaver dominance in three Connecticut watersheds.
Approach:The proposed work will consist of the following three components: 1. Use STELLA modeling software to examine ecologically significant hydrologic conditions under identified differences between pre-colonial and modern reference conditions. 2. Conduct a paired-watershed study comparing modern hydrology and morphology of beaver-dominated rivers with similar rivers in watersheds with little beaver impact. 3. Develop an Ostracoda-based tool to quantify beaver impact. Tool development will focus on modern habitat and, if successful at predicting beaver impact, will be used to retrodict beaver dominance from sediment cores.
Expected Results:This research will begin quantification of baseline fluvial conditions, focusing on the impacts of beaver on the flow regime and morphology of rivers in Connecticut. A paired-watershed study will provide this quantification under modern conditions. This research is expected to show that beaver activity increases the groundwater table, resulting in hydrologic differences from the modern reference condition such as increased baseflows, shortened duration of droughts, and increased duration of high flows. This research is also expected to show that beaver activity results in increased sediment and hydraulic diversity.
Since actual measurement of the historic environment will provide superior knowledge of baseline conditions, this research proposes development of an Ostracoda-based paleoecological tool. If this tool can be successfully applied to retrodict habitat from sediment cores, it is expected to demonstrate that fluvial habitat was dynamic, with transitions in time from beaver ponds to wet meadows to free-flowing river and back to beaver ponds. The quantified impacts of beaver activity can be placed in the full fluvial context through the conceptual models developed in this research. The results from this study will enhance river remediation efforts by furthering our understanding of fluvial biogeochemistry and ecology.
Supplemental Keywords:Castor canadensis, Ostracoda, fluvial geomorphology, river restoration, paleoecology, paired watersheds, STELLA, watershed model, hydrology, natural flow regime,