KONSENTRASI SEDIMEN SUSPENSI RATA-RATA KEDALAMAN BERDASARKAN PENGUKURAN 1, 2, DAN 3 TITIK PADA ALIRAN SERAGAM SALURAN TERBUKA

Abstract

The most appropriate and précise method for determining suspended sediment concentration or suspended sediment discharge in channels is by sampling of suspended sediment data directly from the channel. Depth-integrated and points-integrated-sampling are the methods that generally used to obtain depth-averaged suspended sediment concentration. Points-integrated-sampling method is considered to be more accurate compared with depth-integratedsampling. However, points-integrated-sampling method needs the profile of suspended sediment concentration at the overall depth, which means that the method needs much more times and cost to collect data sampling. The pointsintegrated- sampling method will be more useful, if the data sampling can be collected only at certain points. Whether or not the data of suspended sediment concentration taken at certain points – i.e., at one, two, or three points – is sufficent to determine the depth-averaged suspended sediment concentration, it will be analyzed in this report, based on laboratory and field data. One hundred and twenty-five (125) profiles of suspended sediment concentration of laboratory data − measured in flume at 5 different positions in transversal direction, from the center to the edge of channel −, and fifty (50) profiles of field data − measured in Mataram irrigation channel at 5 different positions − are analyzed. For each profiles, the depth-averaged of suspended sediment concentrations are calculated and compared with the ones obtained from one, two, or three points of measurements. The results of the analyzed data show that the depth-averaged suspended sediment concentration, y C , can be determined from one, two, or three points of measurements, i.e., at y = 0.4 D for one-point of measurement, at y = 0.2 D and 0.8 D for two-points of measurements, and at y = 0.2 D, 0.4 D, and 0.8 D for three-points of measurements, according to the Equations 9, 10, and 11 of this report. In the range of the analyzed data, the equations are valid both for laboratory and field data, and for the data collected from the center to the edge of the channel.