Prediction of water amount and its movement through natural expansive soils due to ground water or water of irrigation is very important for engineers. This movement may affect drainage efficiency, pollutant movements, safety of constructions, canals lining and design of public and water structures. Present research is carried out to investigate; 1) Change of physical properties of swelling soils due to its saturation change. 2) Effect of soil swelling on the hydraulic characteristics of such type of soil. 3) Structural behavior of such soils under footings with different moisture contents. 4) The applicability of GA technique for estimating two parameters included in van-Genuchten model. Unsaturated functions of soil are parameterized using van-Genuchten model 1980. Unsaturated flow model is solved numerically using the finite element technique. A practical technique for estimating the unsaturated hydraulic properties of the soil was developed on the basis of van-Genuchten model and Genetic Algorithm (GA). These parameters are estimated through the inverse analysis of the transient change of saturation distribution along soil specimens which are sampled from different geographic locations in Egypt. The results showed that: i) Physical properties change of soil due to swelling has major effect on water movement through these soils and on their water holding capacities. ii) Such type of soils swells under the footing with low water contents and settlements with high ones, so this behavior is dangerous for the buildings constructed on it. iii) Swelling of these soils improves its cultivation characteristic, so these soils are more suitable for cultivation. iv) GA is a promising technique for parameters estimation in the inverse solution method