The Groundwater Project

Introduction to Karst Aquifers

Book Cover for Introduction to Karst Aquifers
Publication year: 2022
Number of pages: 216

ISBN: 978-1-77470-040-2
https://doi.org/10.21083/978-1-77470-040-2

Authors:

Eve L. KunianskyUnited States Geological Survey, USA
Charles J. TaylorKentucky Geological Survey / University of Kentucky, USA
John H. WilliamsUnited States Geological Survey, USA
Frederick PailletUnited States Geological Survey /  University of Arkansas, USA

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Last Update: 29 December 2023
Released: 8 May 2022

Description

The focus of this karst aquifer book is on water supply in formations composed of rocks that can dissolve (aquifers composed predominantly of carbonate and evaporite rocks). The study of carbonate and evaporite sedimentary rocks is a complex field in geology involving physical, chemical, and biological processes along with an understanding of sedimentation in fluvial and marine environments. Thus, the study of karst aquifers is interdisciplinary because investigating them involves geologic mapping, geophysics, geochemistry, fluid mechanics, geomorphology, hydrology, numerical modeling, and microbiology. Most hydrogeologists develop their skills related to karst aquifers on the job or through study for an advanced degree and continue learning throughout their careers. The purpose of this introductory book is to expose readers to the complexity of flow in karst aquifers and the many methods from various disciplines that have been applied to study and characterize karst aquifers for water supply.

Sections 1 through 3 present the important topics pertaining to groundwater flow in karst aquifers in a general way. The rest of the book provides details about the methods of characterization mentioned in the first section. The last
section describes mathematical models to provide a general understanding of the types of models applied in Karst settings.

Interview with Authors

Contents

1 INTRODUCTION

2 KARST CONDUIT FLOW DEVELOPS BY GEOCHEMICAL AND FLOW PROCESSES

2.1 Formation of Karstic Conduit Flow Systems

2.2 Deep Chemically Aggressive Water Forms Interconnected Conduits

2.3 Water Table Decline and Fluctuation Forms Interconnected Conduits

2.4 Summary of Formation of Conduit Flow

3 HYDROGEOLOGIC CHARACTERISTICS OF KARST AQUIFERS

3.1 Karst Drainage System

3.2 Karst Occurrence Where Soluble and Less Soluble Units Occur Together

3.3 Multiple Porosity and Permeability Structure

3.4 Variance in Surface-Water and Spring Discharge in Karst Aquifers

3.5 Conduit Drainage Patterns

3.6 Subsurface Piracy and Karst Drainage Basins

3.7 Vulnerability of Karst Aquifers to Contamination

3.8 Karst Aquifer Flow Characteristics Compared with Aquifers Composed of Other Rock Types

4 FLUID MECHANICS CONSIDERATIONS FOR KARST AQUIFERS

4.1 Limitations of Darcy’s Law for Application to Karst Aquifers

4.2 Reynolds Number as an Indicator of Flow Regime

4.3 Investigation of Onset of Turbulent Flow in Rock Samples

4.4 Fluid Mechanics of Pipes and Open Channels

5 METHODS OF KARST CHARACTERIZATION

5.1 Hydrogeologic Mapping

Enhancing Mapping with Subsurface Data
Enhancing Mapping with Geophysical Data
Surface Geophysics Useful to Karst Aquifer Characterization

5.2 Borehole Testing

Borehole Geophysical Tools Commonly Applied to Any Aquifer Type
Borehole Geophysical Tools Particularly Useful for Characterizing Karst Aquifers

5.3 Water Tracing Tests

5.4 Aquifer Tests

5.5 Use of Water Chemistry Data

Basic Water Quality Data
Use of End Member Mixing to Estimate Groundwater Contribution to Surface Water
Use of Natural Stable Isotopes
Water Quality Issues for Water Supply

6 MATHEMATICAL MODEL APPLICATIONS IN KARST

6.1 Fitting Models

Example Application of Complex Fitting Model Using Stable Isotopes

6.2 Lumped Parameter Models

Example Application of a Lumped Parameter Model

6.3 Distributed Parameter Models

Single Continuum Porous Equivalent Models
Dual Continuum Porous Equivalent Models
Hybrid Models
Discrete Single and Multiple Fracture or Conduit Network Models
Example Comparisons of Single Continuum and Hybrid Models

7 SUMMARY

8 WHAT IS ON THE HORIZON FOR KARST AQUIFER KNOWLEDGE?

9 EXERCISES

10 REFERENCES

11 BOXES

BOX 1 STAGES FROM FRACTURE FLOW TO CONDUIT FLOW

12 ABBREVIATED GLOSSARY OF KARST AND GROUNDWATER TERMINOLOGY

13 EXERCISE SOLUTIONS

14 ABOUT THE AUTHORS