Which of the following is necessary for calculating discharge in Darcy's Law?

Calculating discharge using Darcy's Law requires understanding how fluid moves through porous media. The formula for Darcy's Law is:

[ Q = k \cdot A \cdot \frac{\Delta h}{L} ]

In this equation, discharge (Q) is directly related to the cross-sectional area (A) through which the fluid flows. The cross-sectional area is crucial because it determines the volume of fluid that can pass through a given section of the material over a certain period. A larger area allows more fluid to flow through, increasing the discharge rate, while a smaller area reduces it.

The other options may be related to water movement or properties of the sediment, but they do not directly influence the calculation of discharge in the context of Darcy's Law. For example, tube thickness, water temperature, and silt content may affect permeability or hydraulic gradients, but they are not part of the basic formula needed to calculate discharge itself. Therefore, the cross-sectional area is an essential component in understanding and applying Darcy's Law effectively.