Reservoir and Lake Management - Hydrographic and Geophysical Services

CR has been actively involved with updating bathymetric data and volumetric models for impoundments and other surface water bodies since 1994. We specialize in the acquisition, processing and analysis of high accuracy bathymetric data using state-of-the-science hardware and software, augmented by over four decades of combined experience.

Integration of single-beam bathymetric data with publically available LIDAR data allowed accurate assessment of holding capacity despite low water levels experienced during the survey. Low-frequency sub-bottom sonar profile draped beneath the bathymetric surface model facilitates visualization of sediment and alum deposits in a Municipal drinking water supply reservoir. (Cross-section view)

Unlike many other hydrographic survey projects which may be of relatively limited spatial extent (e.g., channel dredging or marine construction), bathymetric surveys of reservoirs and lakes are typically performed to calculate holding capacity and sedimentation rates. While a data error (bias) of 0.1 foot might be acceptable for other mission objectives, such a bias amounts to an error of more than 3.2 million gallons in a small 100-acre reservoir. CR has developed specialized data acquisition methods and survey platforms that ensure minimal data bias (often <0.02 feet).

While the majority of our reservoir, lake and pond mapping experience has been focused on water bodies in the Northeast US, all of our survey instrumentation is portable and we have successfully conducted projects on the Colorado River, the Great Lakes and in the deep South. Our network of survey vessels spans the Continental US, and we can provide competitive costs for any project.

Survey instruments are selected from CR's equipment pool based on project-specific objectives and site conditions. We own and deploy both digital and analog single beam echo sounders, two portable multibeam echo sounders, both CHIRP and Continuous Wave (CW) sub-bottom profilers (frequencies ranging from 2-24 kHz), side scan sonar and modern magnetometer systems. Survey navigation is provided from our selection of Trimble and Hemisphere DGPS and RTK systems, as warranted. Acquisition is aided by HYPACK navigation software. RTK shoreline surveys may be conducted in the absence of modern topographic data to allow interpolation between near-shore soundings and the reported full-pool elevation. We typically include interactive 3D data visualizations of basin and watershed elevation models created using Fledermaus software, accompanied by viewing software distributable under CR's license with QPS / IVS3D.

Regardless of the instrumentation selected for a project, data are processed into georeferenced formats suitable for analysis using GIS, CADD or Microstation software. We believe that conveying a clear understanding of data limitations to our clients enlightens the data utilization process. Uncertainties associated with bathymetric data are calculated and reported by a Hydrographer Certified by the National Society of Professional Surveyors (NSPS) and the Hydrographic Society of America (THSOA).

Merged Digital Elevation Model showing bathymetric and topographic relief coupled with a side scan sonar mosaic which shows pre-inundation landscape features.(Oblique view) Typical Elevation v. Volume Curve for a Small Reservoir

In many instances, lake and reservoir managers are interested in identifying the distribution of nuisance aquatic vegetation (submerged and emergent), as well as the distribution and thickness of soft sediments or alum deposited by clarifying systems. Acoustic remote sensing allows precision mapping of each of these variables.

There are thousands of drinking water supply reservoirs in the US, and thousands of lakes and other water bodies with water quality issues relevant to public health or ecological risks. In many instances, reservoir capacity estimates are based on decades-old topographic modeling, and TMDL goals may be based on similarly antiquated values. CR anticipates an increasing involvement in refinement of water volume and TMDL calculations by providing the highest conceivable quality data products to our clients.

A partial list of representative projects includes hydrographic and/or geophysical survey work on the following water bodies, most of which are drinking water supplies:

Reservoir and Lake Volumetric and Sedimentation Analysis

  • Seven Catskill / Delaware Watershed DWS Reservoirs for NYC DEP: Cannonsville, Neversink, Roundout, Schoharie, Pepacton, Ashokan (East and West Basins), and West Branch Reservoirs, NY;
  • West Hartford and Central Connecticut Reservoirs, CT;
  • Conesus Lake, NY;
  • Kensico Reservoir, NY;
  • Springton Lake / Geist Reservoir, PA;
  • Connecticut First Water District Reservoirs (Brown, Grupes, Milne and Scotts);
  • Lake Saltonstall, CT;
  • Lake Sidney Lanier, GA;
  • Chattahoochee River, GA;
  • Lake Quinsigamond, MA;
  • Happy Hollow and Robins Hollow Reservoirs, RI;
  • Echo Lake, MA; and
  • Webster Lake (Lake Chargoggagoggmanchauggagoggchaubunagungamaugg), MA.

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