Transient saturated groundwater diffusion
Combining classical elastic storage with Darcy flux yields ∇·(K∇h)=S_s∂h/∂t in a saturated aquifer without internal sources.
Key knowledge
Combining classical elastic storage with Darcy flux yields ∇·(K∇h)=S_s∂h/∂t in a saturated aquifer without internal sources. K can be a symmetric conductivity tensor in an appropriate continuum. For constant scalar K and S_s>0, hydraulic diffusivity is D=K/S_s and h_t=D∇²h. A response across length L has characteristic scale L²/D, with factors set by geometry and boundary conditions.
Values and equations
∇·(K∇h)=S_s h_t; D=K/S_s; τ∼L²/D
- h,L
- hydraulic head and response length scale m
- K
- scalar or tensor hydraulic conductivity m s⁻¹
- S_s
- specific storage m⁻¹
- D
- hydraulic diffusivity in the constant scalar model m² s⁻¹
- t,τ
- time and characteristic response time s
Conditions and scope
- Small classical storage changes, suitable Darcian continuum, negligible density-gradient mass-flux corrections and the stated elastic/deformation assumptions.
- Specify initial head, boundaries, aquifer geometry and coefficients. Recharge/extraction adds an explicitly signed source; leakage, variable density and large deformation require fuller models. Diffusive response is not the same as advective travel time of a water parcel.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual continuity→Darcy equations2.71–2.77 and boundary-value requirements. Tensor notation generalizes the principal-axis form; L²/D is a disclosed dimensional estimate. No claim of a general full poromechanical or contaminant-transport solution.
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