Conceptual model of an unconfined aquifer. A net of wide fractures (aperture widths A0) is embeded into a net of fine fractures (aperture width a0). The aquifer is recharged by meteoric precipitation and by a constant head point input at h0. Water flows down to the valleys dissolving limestone. Modeling domain of of unconfined aquifer with different boundary conditions. The following animation presents the evolution of such an aquifer with even recharge and point input at the top. The upper panel shows aperture widths and dissolution rates, the lower one water flow and its directions.