Geospatial analysis for the identification and mapping of groundwater potential zones using RS and GIS at Eastern Gojjam, Ethiopia

Abstract

Groundwater, an impressive source of quality water particularly for potable and irrigation. Geospatial analysis of identifying and mapping groundwater potential zones significantly reduce the costs and time of exploration and proper allocation of dried boreholes that helps to avoid failure of groundwater withdrawal planning and development. This research aimed to analysis geospatial identification and mapping of groundwater potential zones. In this study, Digital Elevation Model (DEM) data used to prepare a slope and drainage density map. Lineaments (automatically extracted with PCI Geomatica) and land use/land cover maps were derived from Sentinel 2A data. Supervised classification (maximum likelihood classifier) was applied with an overall accuracy of 84.34% and kappa coefficient of 0.825. Rainfall data from twenty-two meteorological stations was used to prepare rainfall thematic map using Inverse Distance Weight interpolation method. All factors were reclassified based on their class value into five classes, namely: ‘very high’, ‘high’, ‘moderate’, ‘low’, and ‘very low’. A Multi-Criteria Decision Analysis with Analytical Hierarchy Process was implemented with a consistency ratio (CR) value of 0.0098, which is < 0.1. Findings were obtained using a weighted sum overlay analysis of each factor's value multiplied by its corresponding weight. Therefore, 12.78% and 24.1% of the total area has ‘very high’ and ‘high’ potential for groundwater, respectively. Whereas, 29.2%, 24.26%, and 9.65% of the zone have ‘moderate’, ‘low’ and ‘very low’ potential, respectively. Finally, the result was validated with borehole data and the overall accuracy was found to be 87.17%. In conclusion, the application of RS and GIS are powerful tools to identify and map groundwater potential areas with a combination of different groundwater contributing factors.