Groundwater Recharge to Discharge

1 RECHARGE AND DISCHARGE IN THE FLOW SYSTEM

1.1 What is Groundwater Recharge?

1.2 What is Groundwater Discharge?

1.3 Recharge and Discharge Areas in the Groundwater Flow System

1.4 Summary

2 PROCESSES CONTROLLING DIFFUSE RECHARGE

2.1 Partitioning of Precipitation at the Earth’s Surface

2.2 Climate and Weather

2.2.1 Describing Climate and Weather

2.3 Precipitation

2.3.1 Moisture-Holding Capacity of the Atmosphere

2.3.2 Characteristics of Precipitation

2.4 Evapotranspiration

2.4.1 Energy at the Earth’s Surface

2.4.2 Evaporation

2.4.3 Evaporation from Different Surfaces

2.4.4 Transpiration

2.4.5 PET versus AET

2.4.6 Evapotranspiration Measurement Methods

2.5 Infiltration Through the Unsaturated Zone

2.5.1 Capillarity and the Matric Potential

2.5.2 Moisture Characteristic Curve

2.5.3 Hydraulic Conductivity of Unsaturated Soils

2.5.4 Darcy’s Law

2.5.5 The Infiltration Process

2.5.6 Quantifying Infiltration

2.6 Redistribution and Recharge

2.7 Streamflow Generation

2.8 Summary

3 GROUNDWATER DISCHARGE AND EXCHANGES WITH SURFACE WATERS

3.1 Discharge Mechanisms

3.1.1 Exchanges Between Groundwater and Surface Water – An Overview

3.1.2 Groundwater Discharge to Streams

3.1.3 Discharge to Lakes and Wetlands

3.1.4 Discharge to Saline Bodies of Water

3.1.5 Springs and Seeps

3.1.6 Geysers

3.1.7 Flowing Wells

3.1.8 Groundwater Abstraction

3.2 Factors that Control Discharge

3.3 Summary

4 THE DYNAMIC NATURE OF RECHARGE AND DISCHARGE

4.1 Recharge and Discharge Lead to Changes in Storage

4.1.1 The Groundwater Level Hydrograph

4.1.3 Methods Used to Estimate Recharge, Discharge, and Changes in Storage

4.2 Seasonal Variations in Timing and Distribution of Recharge and Discharge

4.2.1 Cold Continental Climate

4.2.2 Temperate Climate

4.2.3 Arid and Semi Arid Climate

4.3 Variability of Recharge and Discharge at other Temporal Scales

4.3.1 Subdaily to Daily Variability

4.3.2 Variability Over Longer Periods

4.4 Dynamic Interactions Between Streams and Aquifers

4.5 Summary

5 ALTERATION OF NATURAL RECHARGE AND DISCHARGE

5.1 Groundwater Abstraction

5.2 Irrigation

5.3 Managed Aquifer Recharge

5.4 Recharge, Discharge, and Ecological Systems

5.5 Impacts of Climate Change on Recharge and Discharge

5.6 Summary

6 WRAP-UP

7 EXERCISES

8 REFERENCES

9 BOXES

BOX 1 – The Hidden Recharge From Mountains

Box 2 – Groundwater Recharge In Cold Regions

Box 3 – Modeling Hypothetical Infiltration Event And Overland Flow

Box 4 – Coastal Groundwater Discharge

Box 5 – Thermal Springs In Southwestern Canada

Box 6 – Water Table Fluctuation Method For Estimating Recharge

Box 7 – Mountain Block Recharge In The Andes Of Peru

Box 8 – Monitoring Groundwater Storage Changes From Space

Box 9 – Modeling Recharge And Discharge

Box 10 – Depression Focused Recharge

Box 11 – Atmospheric Rivers

Box 12 – Groundwater-Level Responses To Atmospheric Pressure Fluctuations And To Air Entrapment

Barometric Pressure Fluctuations

Air Entrapment – The Lisse Effect

Box 13 – Seasonal Variations In Groundwater Flow Patterns Near A Willow Ring

Box 14 – Dynamics Of Climate–Groundwater Stream Interactions

Box 15 – How Plants And The Critical Zone Regulate Groundwater Recharge And Discharge In Seasonally Dry Climates

10 EXERCISE SOLUTIONS

11 NOTATIONS

12 ABOUT THE AUTHOR