PREDICTION OF SEDIMENTS DISCHARGE IN WATERSHED WITH TWO TANK MODELS Tedjo Mulyono¹, Jumi 2, Azizah 3
1,Department of civil engineering 2,3 Department of Bussisess Administration, 1,2,3Politeknik Negeri Semarang,
Abstract-Uncontrolled erosion would cause considerable damages, such as soil fertility decline, water structures damage and reservoirs sedimentation. As the data for the sedimentation rate are limited, several models have been developed to predict the surface erosion and the rate of sedimentation. However, the availability of sufficient, diverse and extensive data are needed for the implementation of the models, both for the model calibration and the verification. The result of the analysis shows that both of the Tank Models that represent the erosion- sedimentation rate process, in which Tank Model 1 being the three-tank cascade system and Tank Model 2 being two-tank cascade system, are not optimum. This can be observed from the values of volume error (VE), relative error (RE), root- mean-square error (RMSE) and correlation coefficient (R) that show the effect of 1.5 hours of rain period in the sedimentation rate. The field condition shows considerable sedimentation, on the other hand, the models- simulations show decreasing sedimentation rates. The optimum model-s parameters for Tank Model 1 and Tank Model 2 are 924.51%-1049.26% for the relative error, 50.81% - 121.42% for the volume error, 0.9 for the correlation coefficient and 6703.59- 17,297.85 for the root-mean-square error. The parameters and constant-s values of the models are different relative to watershed condition.
Keywords: Keywords: Sedimentation rate, surface runoff, rainfall, tank model