PREDICTION OF SCOURING IN THE BRIDGE PILLAR ON INTERMITTENT RIVER

In the planning for bridge pillar in the river, things that need to be considered are the stability and strength of pillar. Other things that also should be taken into consideration in planning is scouring that occur after the bridge pillars exist. The objective of research is to predict scouring in the river due to the influence of the pillars. This research was conducted on the intermittent river in the eastern side of Palu Bay in Central Sulawesi, Indonesia. In this area, there are eight rivers but only four rivers have bridge with three spans, include Taipa River, Labuan River, Lambara River and Toaya River, and all these rivers flow toward Palu Bay. The method used in this research is by calculate and directly measure the variables that affect on the scouring height, such as catchment area, river slope, sediment diameter, rainfall, pillar width, average velocity and height of flow. By taking into account the effect of those variables, the results that are achieved in this research are closer to the higher of scouring around pillars from direct measurement in the research locations. This study is also compared with those conducted by previous researchers, with the results show that the closest result is the Carsten and Froehlich equation.