Data-base system for northern Midwest regional aquifer-system analysis

Abstract

A computerized database system was developed to facilitate collection and use of large quantities of data for a model study of the Cambrian-Ordovician aquifer system in the Northern Midwest. Input to the database system consists of either point values or digitized contour maps of hydrogeologic data required by the model. Uniformly spaced model-node values are then computed from the discrete data by two-dimensional interpolation. Nonuniformly-spaced modal values may be obtained by fitting two-dimensional polynomials (bicubic splines) to surfaces formed by uniformly spaced points and solving for the surface values at the node locations. The database system has the following attributes: 1) manual handling of data is minimized and machine handling of data is maximized, 2) given unequally spaced point data over the extent of the study area, model input arrays for any reasonable uniform node spacing can be rapidly computed, 3) accuracy of computed node values are generally compatible with accuracy and spatial distribution of point data, 4) a relatively large class of nonuniformly spaced node configurations can be computed, 5) data within files can be easily accessed and edited, and 6) the occurrence of data processing errors at various stages of database generation is monitored by machine contouring the computed grids.