Riffles and pools have important roles for a river ecology and river environment. It is useful to develop a method for creation of riffle and pool. Our final goal is a development of technical method for creation of riffles and pools by means of over flow from weir. As first stage of it, we have studied that the characteristics of scours created by over flow from a sharp crested weir and an inclined weir. The main results of this study are as follows