Elastic specific storage of a saturated aquifer
Specific storage S_s is water volume released per aquifer bulk volume per unit decline in hydraulic head.
Key knowledge
Specific storage S_s is water volume released per aquifer bulk volume per unit decline in hydraulic head. In the classical small-strain, constant-total-stress model, S_s=ρ_wg(α+nβ_w), combining porous-medium compression and water expansion. This storage describes an elastic head response, rather than the total amount of water occupying pore space.
Values and equations
S_s=ρ_wg(α+nβ_w)
- S_s
- elastic water release per bulk volume per head decline m⁻¹
- ρ_w
- water density kg m⁻³
- g
- gravitational acceleration m s⁻²
- α,β_w
- aquifer and water compressibilities in the stated model Pa⁻¹
- n
- porosity 1
Conditions and scope
- α is the relevant positive bulk aquifer compressibility with respect to effective stress; β_w is water compressibility and n porosity. Use the classical vertical-stress/deformation approximation and nearly constant density coefficients.
- Large/inelastic compaction, varying total stress and fully coupled three-dimensional poromechanics require a broader storage law. A pressure drop changes effective stress, while porosity alone does not determine S_s.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual§§2.9–2.10 effective-stress and water/aquifer-compressibility derivation, equation2.60 and§2.11 classical-deformation limits. Used decoded original equation alt text; corrected verbal sign ambiguity by defining release per decline, not copying the source's intermediate dh sign slip. No dated aquifer-property ranges or resource-yield judgments.
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