Procedural Documentation and Accuracy Assessment of Bathymetric Maps and Area/Capacity Tables for Small Reservoirs

Abstract

Because of the increasing use and importance of lakes for water supply to communities, a repeatable and reliable procedure to determine lake bathymetry and capacity is needed. A method to determine the accuracy of the procedure will help ensure proper collection and use of the data and resulting products. It is important to clearly define the intended products and desired accuracy before conducting the bathymetric survey to ensure proper data collection. A survey-grade echo sounder and differential global positioning system receivers were used to collect water-depth and position data in December 2003 at Sugar Creek Lake near Moberly, Missouri. Data were collected along planned transects, with an additional set of quality-assurance data collected for use in accuracy computations. All collected data were imported into a geographic information system database. A bathymetric surface model, contour map, and area/capacity tables were created from the geographic information system database. An accuracy assessment was completed on the collected data, bathymetric surface model, area/capacity table, and contour map products. Using established vertical accuracy standards, the accuracy of the collected data, bathymetric surface model, and contour map product was 0.67 foot, 0.91 foot, and 1.51 feet at the 95 percent confidence level. By comparing results from different transect intervals with the quality-assurance transect data, it was determined that a transect interval of 1 percent of the longitudinal length of Sugar Creek Lake produced nearly as good results as 0.5 percent transect interval for the bathymetric surface model, area/capacity table, and contour map products.

Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012

“…Lines were created at 100-ft intervals and oriented perpendicular to the shoreline. The transect spacing was computed to optimize data coverage and accuracy and resulted in 69 data-collection lines spaced at intervals representing approximately 1 percent of the longitudinal distance of the study area (Wilson and Richards, 2006) (fig. 2).…”

Bathymetric map and area/capacity table for Castle Lake, Washington

“…Topographic, or bathymetric, point density is a primary factor controlling DTM accuracy. Wilson and Richards (2006) find a 3-14 percent average reduction in computed volume at transect intervals less than 120 m and a 36 percent average negative bias between 120 and 240 m intervals. Transect intervals for our survey are generally 60-150 m, producing 190,827 depth measurements (after filtering out 12 percent of the recorded points owing to the shallow water blanking distance of the ADCP and the removal of submerged trees that interfered with the surface model).…”

“…Vertical accuracy is the primary metric to assess topographic and bathymetric elevation models (for example, Federal Geographic Data Committee [FGDC], 1998). As discussed in Wilson and Richards (2006), the largest source of uncertainty is commonly the depth measurement (the ADCP in this case). Because of this, accuracy of other factors is commonly overlooked, or assumed to be within equipment manufacturer's specifications.…”

“…Although airborne lidar data had relatively regular point spacing, 40 percent of the bathymetric survey area had less than one point per 100 square meters. In areas of low topographic relief and roughness, simple interpolation algorithms are appropriate, but relatively low point density (that is, large transect intervals) and non-survey grade depth measurements caused our survey to be less accurate than bathymetric surveys conducted on similarly sized lakes (Wilson and Richards, 2006).…”

Sedimentation survey of Lago Lucchetti, Yauco, Puerto Rico, September 2013–May 2014

“…1). The fathometer was calibrated prior to each day of the survey by using a bar check (Wilson and Richards, 2006).…”