Numerical Investigation the effect of Groundwater Uplift on the Interface Between Fresh and Saline Water and Mixing Zone in the Aquiefrs Adjacent Deserts

Most parts of Iran have arid and semi-arid climates. Therefore, many deserts and playas have been formed in these areas. In the present study, the return of saline water due to the groundwater head increase in the aquifers with the usage of SUTRA numerical model, was investigated. In order to assess the wedge behavior of saline water in transient state, the toe length of the wedge is analiezed. The changes in the hight of wedge shape due to the time is measured.  The results showed that: a) with the progression of the wedge behavior, its height is getting earlier to the steady state in comparison to its length, however in the return time, they both reached the steady condition at the same time. b) Unlike the wedge's length, which reachec the steady state earlier than the progession time, its height has an equal time to reach the steady condition in both states (progression and return). The achieved results also showed that due to the mixing processe, the mixing zone expanded earlier in return phase. Also, as the wedge approached the steady condition, the area of mixing zone decreased gradually.