Core Concepts#

Understanding Groundwater Transport#

Groundwater transport involves the movement of solutes through porous media. The key concepts in gwtransport include:

The pore volume distribution describes how water flows through different pathways in a heterogeneous aquifer. This distribution is characterized by:

Residence time is the time water spends in the aquifer between infiltration and extraction points. It depends on:

The retardation factor accounts for processes that slow down solute transport relative to water flow:

Conservative tracers (R = 1): Move with the same velocity as water
Temperature (R = 2): Often retarded due to heat exchange with the solid matrix
Reactive solutes (R > 1): Delayed by sorption or chemical reactions

Temperature variations in infiltrated water act as natural tracers because:

The gamma distribution model assumes that pore volumes follow a gamma distribution with parameters:

\[f(V) = \frac{1}{\Gamma(k)\theta^k} V^{k-1} e^{-V/\theta}\]

Where: - \(k\) is the shape parameter - \(\theta\) is the scale parameter - Mean = \(k \cdot \theta\) - Variance = \(k \cdot \theta^2\)

Direct computation of pore volumes from flow field data:

The transport equations are solved using an advection-dispersion framework that accounts for: