Soluciones semianalíticas en estado estacionario para evaluar la distribución bidimensional de la carga hidráulica inducida por una presa soterrada en un acuífero inclinado con recarga artificial del acuífero y bombeo

Abstract

Underground dams are a technology for artificially increasing existing groundwater resources. They modify the natural groundwater flow in aquifers and, typically, cause hydraulic heads to rise upstream and fall downstream of the dam. However, such modifications must be defined to forecast their environmental, economic and/or social impacts. A steady-state semi-analytical solution is proposed for evaluating the 2-D distribution of hydraulic head caused by an underground dam fully penetrating a homogeneous and inclined aquifer. The dam is impermeable, of rectangular shape and its length concerns a limited part of the aquifer width. The developed solution is based on the method of fundamental solutions. The analysis of the semi-analytical solution included sensitivity tests and a satisfactory comparison with numerical modelling. Dimensionless graphs relating the dam geometry to maximum hydraulic-head variations up-and downstream of the dam are given. The proposed solution was applied on two field sites giving very satisfactory results. A semi-analytical solution is also developed for an artificial recharge area and/or a pumping well near the underground dam. Interestingly, in the case of highly permeable aquifers, the increase in hydraulic head created by the dam may be much higher than that created by managed aquifer recharge (MAR), despite high injected flux. These semi-analytical solutions will be useful applications for assessing the long-term spatial distribution of hydraulic head induced by underground dams, or for testing the combination of dams with pumping wells or MAR technology. They are intended to guide the design of such structures, especially to quickly test various configurations.