Table of Contents

EXECUTIVE SUMMARY
1 INTRODUCTION
2 RECHARGE CONCEPTS AND TERMINOLOGY
       SUMMARY OF SOIL PHYSICS PRINCIPLES
          Water Content
          Hydraulic Head and Pressure Head
          Soil-Water Retention Curve
          Hydraulic Conductivity
          Infiltration, Redistribution and Recharge
    CONTAMINANT TRANSPORT
    DIFFUSE RECHARGE CONCEPTS
3 METHODS TO QUANTIFY DIFFUSE NATURAL RECHARGE
       PHYSICAL METHODS FOR DETERMINING DIFFUSE RECHARGE
          Soil-Water Balance
          Soil-Water Storage
          Lysimeter Measurements
          Darcy Flux Method
          Plane of Zero Flux Method
          Soil Temperature Methods
          Electromagnetic Methods
          Groundwater Basin Outflow Method
          Water-Level Fluctuations
          Stream Gauging
   CHEMICAL METHODS FOR DETERMINING DIFFUSE RECHARGE
          Chemical Methods in the Vadose Zone
          Chemical Tracers in Aquifers
   MATHEMATICAL MODELS FOR ESTIMATING RECHARGE
          Soil-Water Balance
          Stream Gauging
          Darcy Flux and Plane of Zero Flux Methods
          Soil-Water and Groundwater Models
          Lysimetry
          Other Physical Techniques
          Chemical Methods
          Aquifer Hydrochemistry
5 CONSIDERATIONS AND RECOMMENDATIONS FOR SELECTING
    RECHARGE ESTIMATION TECHNIQUES
       CONSIDERATIONS
       RECOMMENDATIONS
          Estimation Methods for Humid Climates
          Estimation Methods for Arid Climates
6 FUTURE RESEARCH
REFERENCES
GLOSSARY
Appendix A
ESTIMATE OF DIFFUSE ANNUAL RECHARGE

Abstract

A Risk-Based Corrective Action analysis of a site suspected of chemical contamination requires site-specific knowledge of the rate water infiltrates through the soil to the water table. A comprehensive discussion of the current physical/chemical methods and mathematical models available to quantify those rates along with suggestions for selecting an appropriate technique, depending on site conditions, are provided.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	American Petroleum Institute
Pages
ISBN