| Abstrakt: |
In the past few years, significant progress has been made to improve the quality of water area–storage capacity data and to assess the potential of empirical models in bathymetry mapping. However, little effort has been made in the area of predicting techniques for large and remotely inaccessible reservoirs, respectively. This paper presents a case study which draws on empirical modeling and geographic information system (GIS) as a satellite-derived technique in concert with field measurement method to development surface area–storage capacity relationship using a Digital Elevation Model. The satellite-derived technique has provided a tool to carry out reservoir capacity mapping rapidly, frequently, and economically. The accuracy of this satellite-derived technique is enhanced when used with empirical relationship between the reservoirs’ parameters (volume and area). However, the use of existing empirical relationship is limited to the region for which they were developed. Hence, this study developed a water surface area–storage capacity relationship for Gurara reservoir for Nigeria region. This empirical equation, in the form of ‘Capacity = 1.928 × area1.506’, was developed based on both field measurement and remote sensing. The validation process adopted in the study indicates accuracies of 86.7% and 73.3% for the water surface areas and reservoir capacity (volume), respectively. Using this validated technique, the study inferred that the Gurara reservoir has lost a capacity of 65,058 m3in a period of 10 year period after the reservoir was constructed, with water being diverted from the reservoir annually to the city of Abuja, the Federal Capital Territory for water supply. |
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