A review of specific storage in aquifers

Abstract

Specific storage, which represents the aquifer’s capacity to release water from or take into storage when water level changes, is an important aquifer property required for transient groundwater modeling and water resources management. This review synthesizes the published literature on using different methods to estimate field specific storage of aquifers. The field methods include pumping tests, slug tests, and analyses of sea tides, atmospheric loading and earth tides, and seismic waves. The present state of knowledge concerning the analytical and numerical models and parameter estimating procedures are presented and applications of these models are discussed. Specific storage values from 182 different field sites are collected, covering a wide range of aquifer materials, including unconsolidated deposits and rocks. The geometric mean of specific storage for unconsolidated deposits mainly range from 10−5 to 10−4 m−1. The geometric mean of specific storage for different types of rocks mainly range from 10−7 to 10−6 m−1. The corresponding hydraulic conductivity shows a wider range of variation than the specific storage. There is not a clear relationship between specific storage and hydraulic conductivity for all the data but a positive correlation can be found for some types of aquifer materials. Specific storage is positively correlated with porosity of the aquifer. A comparison of the different field methods is presented and future research directions are recommended.