EXPERIMENTAL TEST OF SAND ROUGHNESS AS A BASE LAYER OF CANALS

Abstract

Flow in an open channel is flow that has a free surface. The free surface is a meeting of two fluids with different densities, namely air and water, where the density of air is much smaller than the density of water. Obstacles to flow in natural channels are important in overcoming engineering problems of hydraulics and sedimentation. The biggest difficulty in using the Manning Formula is determining the roughness coefficient n, because there is no specific way to select the n value. Many natural channels have permeable bottom layer materials such as gravel, sand and others. From the test results and data analysis, it was found that the channel base used sand with a slope of 0.25%, 0.50%, 0.75%, 1.00%. The roughness values for the sand base layer were 0.0115, 0.0124, 0.0123, and 0.0120, respectively.