Accuracy Evaluation of Satellite-Based Bathymetry Data Extracted from Digital Elevation Model against Echo Sounder Measured Data in Gurara Reservoir, Nigeria

Abstract

Digital elevation models are satellite-derived imageries which comprise valuable source of elevation data for engineering applications. More specially, Digital elevation models are often used in geographic information systems, and are among the critical input parameters for digitally-produced sensitivity maps. In this regard, this paper proposes a method of generating bathymetry data from Digital elevation models which is easily accessible. The case study is the 700 mcm Gurara reservoir located in Kaduna, North West Nigeria. The extracted elevations are reported using a computer program that registers the extracted digital data to determine the reservoir boundary area, and generate topographic layer to create triangular irregular network. The accuracy of the generated bathymetry data was reported using Root Mean Square Error observation standard deviation ratio (RSR), the Percent bias (PBIAS) and coefficient determination (R2). All these accuracy statistics were computed using the ground coordinates of 10000 reference points for the case study. The reference data was collected from bathymetry survey conducted using Echo Sounder. The results showed that the accuracies for the prepared DEMs are suitable for engineering applications but inadequate to meet the standard required for precise engineering study. In general, digital elevation derived bathymetry data can be used only for investigation and preliminary studies especially when there is limited access for real-time investigation.