The Groundwater Project

Variable-Density Groundwater Flow

book cover for variable-density-groundwater-flow
Publication year: 2022
Number of pages: 92

ISBN: 978-1-77470-046-4
https://doi.org/10.21083/978-1-77470-040-2

Authors:

Vincent E.A. Post: Edinsi Groundwater, The Netherlands
Craig T. Simmons: Flinders University, Australia

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Last Update: 31 January 2023
Released: 2 June 2022

Description

Differences in groundwater density are caused by variations in solute concentrations and/or temperature. Density-driven flow  is important across a range of groundwater settings  but  its significance  and complexity is sometimes underestimated. This book summarizes the main causes for, and manifestations of density-driven flow, in groundwater systems. Techniques used to understand, conceptualize, model, predict, and measure density-driven flow in groundwater are described.

Theoretical and experimental matters (including field-based investigations) are dealt with. Guidelines for assessing when density effects become important and corrections that are needed to correctly infer groundwater flow in systems where the density  varies  are discussed. The book highlights the difficulties and possibilities of simulating variable-density groundwater systems using numerical models.

It describes the challenges and opportunities for measuring density-driven flow directly in field-based groundwater settings. It also discusses some areas of ongoing research and debate.

Interview with Authors

Contents

1 INTRODUCTION

2 WHAT CAUSES GROUNDWATER DENSITY VARIATIONS?

3 QUANTIFYING GROUNDWATER FLOW IN THE PRESENCE OF DENSITY VARIATIONS

3.1 Equivalent Freshwater Head

Horizontal Flow
Vertical Flow

4 TYPES OF DENSITY FOR GROUNDWATER FLOW

4.1 Free Convection

4.2 Stable and Unstable Density Configurations

4.3 Transport Processes in Groundwater

4.4 Landfill Leachate Plume Example

5 DIMENSIONLESS NUMBERS

5.1 Mixed Convection Ratio

5.2 Rayleigh Number

5.3 Wooding Number

5.4 Sherwood Number

5.5 Nusselt Number

6 MATHEMATICAL MODELING

6.1 Governing Equations

6.2 The Elder Problem

6.3 Predictability of Convective Flow Patterns

Homogeneous Systems
Heterogeneity

7 SELECTED RESEARCH TOPICS

7.1 Field Scale Detection of Free Convection

7.2 Chemical Reactions in Variable Density Flow Systems

7.3 Future Research Directions

8 EXERCISES

9 REFERENCES

10 BOXES

Box 1 – Free Convection Cake

Ingredients
Preparation

11 EXERCISE SOLUTIONS

12 NOTATION

13 ABOUT THE AUTHORS