Analysis of effective parameters on water head over the underground dams and an innovative methodology for estimation of it

Underground dams have been considered for ground water resources development and prevention of ground water losses all around the world especially in arid and semi-arid regions. A physical model with dimensions of (4x0.85x.m) accompanied by a numerical model, MODFLOW, were used to simulate the flow in the reservoir of ground water dams and thus the head of water over the crest was determined. Numerical model was calibrated based upon more than 00 data, which are carried out on the physical model in different conditions. Studies clarified that the most important factors which control the height of water on underground dams are: discharge, the height of dam, initial level of water table, hydraulic conductivity of the aquifer,dam thickness and finally bed rock slope. Also a formula for estimating the height of water on underground dam (H) was derived form: H=S*F in which S is a factor reflects the condition of discharge, hydraulic conductivity, dam thickness and bed rock slope and can be computed by the equation of S=ST.Sq.Sk.Ss and F is a power product of dam height (Hdam) to initial water table level (H0) ratio and were calculated from formula F=.06(Hdam/H0)-0.7900.