Volumetric Lake Modeling - Used SONAR equipment, a Gheenoe, LiDAR data and some open source geospatial software to map and model the volume of a local lake.

Mountain Lake Photographs

Point of View Photograph

Aerial Photograph

This goal of this self-imposed project was to test the capabilities of open source software to create a composite elevation model. This combined model would consist of topography (land) and bathymetry (sub-marine). Then perform volumetric lake calculations.

Terrain Model From LiDAR

The surrounding terrain for the lake was modeled from LiDAR. There was no point data for the lake, so the software can create some odd results for what should be a flat feature.worth noting the LiDAR was flown during the dry season, capturing some of the exposed lake bottom to the northeast.

Terrain model (DEM) with lake flooded to a specific elevation. Boat transects with indicate depth. Patch of light blue in north-center of lake indicates low water level and bottom of lake captured by LiDAR.

Combining Topography & Bathymetry

The lake model to the left incorporates the crude bathymetric survey data and the LiDAR point data. Notice that the northern part of the lake is shallower than the southern area. This corresponds with the shallow spot captured by the LiDAR.

Oblique Views and Volumes

Oblique aerial view of lake from the north-east.

Oblique water model view, illustrating water levels at 97 feet.

Model Comparisons

Using the DEM from the LiDAR points only (water surface captured in dry season), the modeled depth is 2.8 feet, area is 42 acres and volume is 125,807 cubic yards. Using the composite model (topography and bathymetry), the volume increases over 100%; the modeled depth is 9.5 feet, area is 42 acres and the volume is 280,242 cubic yards.

Composite Elevation Models

Creating a composite elevation model undoubtedly, and obviously, creates a model of the lake with much greater accuracy. With GIS data, most all data is mapped, and publically provided, above water. Collecting data below water surfaces requires special efforts and equipment, whether using weights and rope, or sonar equipment; however, the information is easily integrated with topographic data to create one seamless product.

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