The finite element method was applied for solving a seepage problem involving unknown parameter estimation by back-analysis. The experimental model was an old, superannuated Fukada earth dam. The model was assumed to be one of anisotropic, plane quadratic isoparametric elements and two-dimensional flow. The permeability through the saturated and unsaturated zones was back-analyzed by a trial and error procedure. To solve this problem a series of repeated calculations were carried out, taking various possible assumed parameter. Initially the difference between the measured and calculated seepage lines was found to be very large, and finally a negligible difference was obtained.
An estimate of the distribution of the world's water supply based on the U.S. Geological Survey has indicated that only 0.05% is held on land and in the atmosphere, the rest existing Is ice caps, glaciers and oceanic salty water functioning as a reservoir in the natural hydrological cycle. Surface, ground and min water are the main important sources of fresh water for living organisms on land. Continual extraction of ground water has a disadvantage of lowering the ground water table and creating high salt concentrations undesirable for irrigation water. The concept of dam construction is very old, has been done since ancient times to make water reservoirs, diverting river courses, producing hydropower and for irrigation of agricultural land. The Aswan dam on the river Nile in Egypt is a good example of dam work this century. The Aswan dam has dramatically changed the agricultural sector in Egypt. Presently, the construction of dams for irrigation crop production has been receiving more attention as a means of increasing crop production to feed the overgrowing population of the world. Sometimes, long-established hydraulic structures such as embankments and dams develop leakage and other problems. Earth dams are constructed by simple excavation work to make water reservoirs.
