Foreword

Groundwater science began as a modern discipline in 1856 when Henry Darcy published his “law” for the simple relationship between volumetric flow rate and the gradient of hydraulic head. Soon thereafter, this led to mathematical descriptions of steady flow to wells in homogeneous horizontal aquifers. But decades were to pass before the first mathematical descriptions for unsteady flow to wells in confined aquifers were published by C.V. Theis (1935) of the United States Geological Survey. For Theis to develop this description, he needed to understand the origin of the water pumped from confined aquifer wells. Recognition of the origin of this water was elusive because it had to be extracted from knowledge at the interface between aquifer hydraulics and geomechanics and to achieve this, scientific intuition had to evolve into quantitative thinking by the leading groundwater intellects of the time. This book: Groundwater Storage in Confined Aquifers by Herbert F. Wang explains that water from storage in confined granular aquifers comes from compression of the aquifer skeleton and expansion of the water as water pressure declines during pumping. Not only does this book explain the principles and processes involved, but it provides the interesting history of this discovery as a Wild West saga recounted to show how the scientific method was used to solve the mystery of the origin of confined aquifer water.

For decades, the author of this book has conducted internationally recognized research. His teaching has focused on rock mechanics and hydrogeology and this historic record of the unfolding understanding of aquifer storativity is his favorite lecture.

John Cherry, Groundwater Project Leader
Guelph, Ontario, Canada, November, 2020