Groundwater flow through an unconfined aquifer resting on a semi-pervious layer

Abstract

The differential equation of flow through an unconfined aquifer resting on a semi pervious layer considers the leakage factor of the semi pervious layer, the transmissivity and, the specific yield of the aquifer as hydro-geological constants. The purpose of this paper is to verify the suitability of the aforementioned constants for the simulation of the distribution of the piezometric heads in the upper ‘unconfined’ part of the Dujailah Aquifer in Iraq. A finite differences explicit model for the simulation of the piezometric heads has been constructed and verified against the maximum historical field measurements during June 1977 of a four months irrigation season. Statistical analysis, based on the calculations of the root mean squared error RMSE and the squared sum of residuals SSR values, indicated best fits between the simulated and measured piezometric heads at values of the specific yield (SY) <= 0.1 and a leakage factor (α) equal to (150) m.