ABSTRACT
A research project dealing with the determination and monitoring of subsidence (vertical movements) of A.B.U. Dam as a result of increase in volume of water in the reservoir, causing sudden load (causative effects) on the dam is discribed. It is of great interest and importance to design a program to detect, direction of these movements so as to plan (an) appropriate measure(s) against the disastrous consequences of such movements. These require precise instruments of high measuring accuracy and reliability, refined survey methods incorporating quick and frequent check operations and analysis of results. The Dam is an earth dam. A review of current monitoring techniques was given. Repeated Precise levellings of elevation of monitoring stations were made before the start of rainfall (low water level) in April, and after maximum rainfall (highest water level) has been recorded, in August. An approach whereby upper and lower stadia staff readings were not recorded but using only the center hair reading of both left and right graduations on staff was adopted. The advantages of this method were stated. Rigorous least squares adjustment was carried out. Analysis of the data by Chi square test was done to determine the acceptability of the levelling. It is acceptable at the 95% confidence limit. The deformation analysis was done using the