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Reconstructing Water Quality Histories in Western Reservoirs. Paul Gremillion, Ph.D., P.E. Associate Professor Civil & Environmental Engineering Department Northern Arizona University. Content. Sedimentation in Reservoirs Direct Indicators of Reservoir History
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Reconstructing Water Quality Histories in Western Reservoirs Paul Gremillion, Ph.D., P.E. Associate Professor Civil & Environmental Engineering Department Northern Arizona University
Content • Sedimentation in Reservoirs • Direct Indicators of Reservoir History • Proxy Indicators of Environmental Conditions • Case Studies
Sedimentation in Reservoirs Source: Reservoir Limnology, Thornton et al.
Direct Analysis of Sediments Can Reveal: Rate of loss in storage capacity.
Direct Analysis of Sediments Can Reveal: Rate of loss in storage capacity. How the rate of capacity loss may change with climate change.
Direct Analysis of Sediments Can Reveal: Rate of loss in storage capacity. How the rate of capacity loss may change with climate change. Erosion patterns associated with wildfire.
Case Study: Watson Lake, Arizona Objective: Collect and analyze sediment cores from Watson Lake to detect historical changes in • Nutrient loading • Primary productivity / trophic state • Sources of nutrients
Case Study: Watson Lake, Arizona Analytical Approach: • Changes in nutrient loading: TN, TKN, TP • Changes in source of nitrogen: Nitrogen-15 • Changes in source of organic matter: N/P, C/N, Carbon-13 • Changes in primary productivity / trophic state: Carbon-13, TP
Conclusions Sediment records in western reservoirs tend to be high in information content: • Magnitude and effects of erosion events. • Changes in water quality. • Changes in watershed characteristics. • Patterns of atmospheric deposition to watersheds.