Straight-Line Intercept Method in Aquifer Volume Calculations

Abstract

Volume calculations in various aspects of ground-water resources evaluation play a significant role. However, these calculations are made by different classical techniques, each of which employs the finite element concept. A common requirement in these techniques is the adaptation of a basic height—like contour interval. The accuracy of the estimated volume is influenced by the subjectivity on the part of the person doing the contouring on a specified contour interval. It is observed that there is a linear relationship between the contour interval and the estimated volume. The basic idea of this paper is to use a simple drawing procedure of a few points of different contour intervals versus the resulting volumes. A regression line is fitted through the scatter of these points. The best volume estimate corresponds to zero contour interval, i.e., the intercept of the straight line with the volume axis. This technique provides a common basis in that different researchers arrive at exactly the same conclusion for a given data set. The proposed method is verified by calculating the reservoir volume of a laboratory dam model with the known reservoir volume. It was found that the estimated volume was off by only 5% of the measured one. Further applications of the method are given for some observed data from the Floridan aquifer and a Black Hills dam reservoir.