Exploring: Reservoir Capacity And Sedimentation Of The Fena Valley Reservoir Guam Completed
The Fena Valley Reservoir, located in southern Guam, is the primary source of water for the United States Naval Base Guam and nearby village residents. At full capacity, the reservoir surface area extends approximately 0.30 mi2, and drains a watershed area of about 5.88 mi2. After reservoir construction, periodic bathymetric surveys, coupled with sedimentation models, can be used to produce estimates of sedimentation rates to evaluate the potential impacts of climate change.
Since the construction of the Fena Dam in 1951, sediment has accumulated in the reservoir and reduced its storage capacity. The reservoir was surveyed previously in 1973, 1979, and 1990 (Kennedy Engineering Inc., 1973; Curtis, 1984; Nakama, 1992) in order to estimate the loss in storage capacity. To determine the current storage capacity, the United States Geological Survey in cooperation with the United States Navy resurveyed the bathymetry of the reservoir in February 2014. This project was part of a comprehensive study to investigate the future of water resources on Guam.
Two methods were used to survey reservoir bathymetry. The first involved use of an integrated Acoustic Doppler Current Profiler and Global Positioning System (ADCP-GPS) (using a Sontek M9 HydroSurveyor ADCP). Horizontal positions were provided by the GPS and bed elevations were computed from ADCP-measured depths and known reservoir water surface elevations at the time of survey. Navigation and data processing were accomplished using Sontek's HydroSurveyor software package. Speed of sound measurements were made with a Conductivity-Temperature-Depth (CTD) profiler and were integrated into the bathymetric survey. The Sontek M9 ADCP is a 5-beam system with 50 degree swath, thus providing increased spatial coverage over single-beam sonar without the additional complexity [e.g. Inertia Measurement Unit (IMU)] of multi-beam sonar equipment.
Reservoir bathymetry was also measured with a multi-frequency, single-beam sonar system with the capability for sub-bottom profiling, i.e. mapping the thickness of deposited sediment within the reservoir. Concurrent with the ADCP surveying, the BSS+3 sub-bottom profiler was deployed (Specialty Devices, Inc.), along with differential GPS (Trimble R10) for positioning. This system was developed specifically for reservoir bathymetry and sediment mapping, and the methods have proven successful for a range of reservoir surveying applications (Dunbar and others, 1999, Obhiambo and Boss, 2004, Anderson and others, 2013). Mapping the sediment deposit with sonar provides an independent check of volume changes computed from historical surveys, which used different methods and may contain much more uncertainty than surveys using modern techniques. The BSS+3 system measures water depth with a 200 kHz transducer and sediment thickness with two additional lower-frequency transducers. Thus, the system provides redundancy with an ADCP survey for reservoir bathymetry as well as sub-bottom profiling capabilities.
Below are publications associated with this project.
Storage capacity of the Fena Valley Reservoir, Guam, Mariana Islands, 2014
Water resources on Guam—Potential impacts of and adaptive response to climate change
Daily reservoir sedimentation model: Case study from the Fena Valley Reservoir, Guam
Storage capacity of Fena Valley Reservoir, Guam, Mariana Islands, 1990
Sedimentation survey of Fena Reservoir, Guam, Mariana Islands, 1979
Below are partners associated with this project.
- Overview
The Fena Valley Reservoir, located in southern Guam, is the primary source of water for the United States Naval Base Guam and nearby village residents. At full capacity, the reservoir surface area extends approximately 0.30 mi2, and drains a watershed area of about 5.88 mi2. After reservoir construction, periodic bathymetric surveys, coupled with sedimentation models, can be used to produce estimates of sedimentation rates to evaluate the potential impacts of climate change.
Since the construction of the Fena Dam in 1951, sediment has accumulated in the reservoir and reduced its storage capacity. The reservoir was surveyed previously in 1973, 1979, and 1990 (Kennedy Engineering Inc., 1973; Curtis, 1984; Nakama, 1992) in order to estimate the loss in storage capacity. To determine the current storage capacity, the United States Geological Survey in cooperation with the United States Navy resurveyed the bathymetry of the reservoir in February 2014. This project was part of a comprehensive study to investigate the future of water resources on Guam.
Two methods were used to survey reservoir bathymetry. The first involved use of an integrated Acoustic Doppler Current Profiler and Global Positioning System (ADCP-GPS) (using a Sontek M9 HydroSurveyor ADCP). Horizontal positions were provided by the GPS and bed elevations were computed from ADCP-measured depths and known reservoir water surface elevations at the time of survey. Navigation and data processing were accomplished using Sontek's HydroSurveyor software package. Speed of sound measurements were made with a Conductivity-Temperature-Depth (CTD) profiler and were integrated into the bathymetric survey. The Sontek M9 ADCP is a 5-beam system with 50 degree swath, thus providing increased spatial coverage over single-beam sonar without the additional complexity [e.g. Inertia Measurement Unit (IMU)] of multi-beam sonar equipment.
Reservoir bathymetry was also measured with a multi-frequency, single-beam sonar system with the capability for sub-bottom profiling, i.e. mapping the thickness of deposited sediment within the reservoir. Concurrent with the ADCP surveying, the BSS+3 sub-bottom profiler was deployed (Specialty Devices, Inc.), along with differential GPS (Trimble R10) for positioning. This system was developed specifically for reservoir bathymetry and sediment mapping, and the methods have proven successful for a range of reservoir surveying applications (Dunbar and others, 1999, Obhiambo and Boss, 2004, Anderson and others, 2013). Mapping the sediment deposit with sonar provides an independent check of volume changes computed from historical surveys, which used different methods and may contain much more uncertainty than surveys using modern techniques. The BSS+3 system measures water depth with a 200 kHz transducer and sediment thickness with two additional lower-frequency transducers. Thus, the system provides redundancy with an ADCP survey for reservoir bathymetry as well as sub-bottom profiling capabilities.
- Publications
Below are publications associated with this project.
Storage capacity of the Fena Valley Reservoir, Guam, Mariana Islands, 2014
The Fena Valley Reservoir is in southern Guam and is the primary source of water for the U.S. Naval Base Guam and nearby village residents. Since the construction of the Fena Dam in 1951, sediment has accumulated in the reservoir and reduced its storage capacity. The reservoir was surveyed previously in 1973, 1979, and 1990 to estimate the loss in storage capacity. To determine the current storageAuthorsMathieu D. Marineau, Scott A. WrightWater resources on Guam—Potential impacts of and adaptive response to climate change
The goals of this joint U.S. Geological Survey, University of Hawaiʻi, University of Guam, University of Texas, and East-West Center study were to (1) provide basic understanding about water resources for U.S. Department of Defense installations on Guam and (2) assess the resulting effect of sea-level rise and a changing climate on freshwater availability, on the basis of historic information, seaAuthorsStephen B. Gingerich, Adam G. Johnson, Sarah N. Rosa, Mathieu D. Marineau, Scott A. Wright, Lauren E. Hay, Matthew J. Widlansky, John W. Jenson, Corinne I. Wong, Jay L. Banner, Melissa L. Finucane, Victoria W. KeenerDaily reservoir sedimentation model: Case study from the Fena Valley Reservoir, Guam
A model to compute reservoir sedimentation rates at daily timescales is presented. The model uses streamflow and sediment load data from nearby stream gauges to obtain an initial estimate of sediment yield for the reservoir’s watershed; it is then calibrated to the total deposition calculated from repeat bathymetric surveys. Long-term changes to reservoir trapping efficiency are also taken into acAuthorsMathieu D. Marineau, Scott A. WrightStorage capacity of Fena Valley Reservoir, Guam, Mariana Islands, 1990
No abstract available.AuthorsL.Y. NakamaSedimentation survey of Fena Reservoir, Guam, Mariana Islands, 1979
Fena Reservoir, in south-central Guam, was constructed in 1950-51 to provide a dependable water supply for the U.S. Navy. At the request of the U.S. Navy, the U.S. Geological Survey conducted a sedimentation survey of the Fena Reservoir during the months of November and December 1979. The sedimentation survey showed that at the spillway elevation, the reservoir has a surface area of 195 acres andAuthorsW. F. Curtis - Partners
Below are partners associated with this project.