ABSTRACT
There are two patterns for erosion in downstream reach of the sabo dam, one is the local scouring by an overflow in between main and counter dams, and the other is bed erosion due to imbalance of sediment transportation along downstream reach of counter dam. Apron and counter dam are usually used for countermeasure of erosion in downstream reach of the dam. More effective countermeasure in downstream reach is desired, because a horizontal distance and an overlapping height of the sabo dam are determined empirically. In present study, erosion in downstream area of the dam and between main and counter dams is discussed experimentally for combinations of overlapping height and horizontal distance between dams. Bed erosion depth does not noticeable around the counter dam, if the counter dam is set behind main dam such that the over flow from main dam can attack on the top of the counter dam.
