Analysis of data from aquifer and well tests in intrusive dikes

Approximate solutions to the problem of groundwater flow in a composite dike-aquifer system are presented for the case that a well in the dike is pumped at a constant rate. These solutions yield curve-fitting procedures to evaluate the drawdown behaviour of wells drilled in a dike. Procedures based on the authors' previous work are described. These contained a distance-drawdown analysis of observation wells with two particular type curves and a time-drawdown analysis of the pumped well. They were tested for validity with model and field tests. In this study, the authors develop a method to analyze the time-drawdown behaviour of individual observation wells in the dike. In addition, general type curves are presented which allow the distance-drawdown behaviour at any time to be analyzed. A computer program is presented to construct time-drawdown type curves; it can be run on a pocket calculator or small computer. Sufficient data are tabulated to construct distance-drawdown type curves. With common type-curve matching procedures early-time transient drawdown data can be analyzed to obtain the hydraulic characteristics of the dike and the product of the storativity and the transmissivity of the country rock. The methods described are illustrated by aquifer test data from two field tests.