Evaluation of Shallow Acoustic Sub-Bottom Profiling Technologies for Measuring Reservoir Sedimentation Thickness and Stratigraphy – Englebright Lake, California

Project ID: 22067
Principal Investigator: Daniel Dombroski
Research Topic: Sediment Management and River Restoration
Funded Fiscal Years: 2022 and 2023
Keywords: None

Research Question

1. What are the capabilities and limitations of different sub-bottom acoustic profilers in conducting geomorphic assessment of reservoir sediment deposits?

2. How does the power, transmit frequency, and pulse frequency variations among different sub-bottom profiling instruments affect the reflected signal and corresponding interpretation of results as compared to known geomorphic conditions?

3. What selection and operational guidelines can be developed pertaining to sub-bottom acoustic profiling instrumentation for reservoir sedimentation studies?

The spatial distribution, volume, and relative grain size of sediment in reservoirs influences management plans through the operational lifespan and decommissioning stage of impounding dams. Reservoir sediment studies are infrequently conducted and historical data are lacking, however, leading to great uncertainty over how to manage infrastructure. Even if bathymetric surveys have been performed (often they have not) in order to estimate storage capacity, little may be known about the sediment characteristics. In a FY 2020 pilot study, our joint Reclamation-USACE team demonstrated that shallow acoustic chirp is a useful tool for recovering pre-impoundment reservoir surfaces and assessing the characteristics of sediment deposits. With a range of available instrumentation largely untested in application to reservoir sedimentation studies, we are proposing a thorough assessment comparing the capabilities and limitations of different sub-bottom profilers at a site with known geomorphic characteristics. The study aims to elucidate the effects of differential instrument characteristics on interpretation of results and develop guidelines concerning the selection and operation of sub-bottom profiling instruments in order to clarify workflow processes for future practitioners.

Need and Benefit

Sub-bottom profiling is an indirect method (as opposed to a direct measurement, like sediment coring) for measuring reservoir sedimentation depth and volume. The proposed research will also indirectly support research needs 2 and 5 in the SSIP, which relate to improved numerical modeling capabilities for reservoir sediment management and the impacts of wildfires on sediment loads and reservoir sedimentation. Outcomes can support any type of reservoir sedimentation study.

Contributing Partners

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Research Products

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Last Updated: 6/22/20