Theory of flow in unconfined aquifers by integrodifferential equations

It is shown that when the diffusion of the deviation of the drawdown from its average value can be neglected, the unsteady flow in unconfined aquifers is governed by an Integrodifferential equation. For incompressible flow this equation reduces to Boulton's delayed yield equation with ε = 3. When the flow is compressible, the kernel can be approximated by Boulton's delayed factor in a range of times whose lower limit approaches zero with the compressibility.