Bed-Load Sediment Profile and Effect of River Bank Erosion on River Cross-Section

Abstract

The processes of lateral and riverbank erosion are among the elements of river morphology dynamic resulting from natural processes and human activities. This process has been studied in detail throughout the research for four months starting from 7 October 2009 to 26 January 2010. In this research, technique of erosion pins were applied at five plots selected along the Chini River in Pahang, Malaysia in order to evaluate the rate of for lateral and river bank erosion. The results in the lateral erosion indicates that, the average highest erosion was recorded at plot 4 (3 cm), followed by plot 3 (2.3 cm), plot 2 (1.42 cm), plot 1 (1.2 cm) and plot 5 recorded the lowest average which is 0.59 cm respectively. Overall, the total average of lateral erosion recorded at all five plots is 8.51 cm. Meanwhile, results obtained from river cross-section variation indicated that plot 1 and 2 show changes from the V shape in early observation to U shape at the end of the observation period. This shows that side-erosion was active in the entire process. Furthermore, plot 3, 4 and 5 remained U shape until the latest observation but it was found that the riverbed was getting shallow. For the regression analysis, two independent variables were selected to relate with rate of river bank erosion namely steep gradient bank height of the bank. These independent variables show a positive relationship with the rate of the side and river bank erosion where the value of r² is 0.820 and 0.645 for both variable of gradient and height. For the analysis of soil particle distribution, the mean value is a sand and very coarse with phi ø -2.00 to phi ø 0.00. The standard Deviation (D) indicates of worst deposition, between phi ø 1.00 to phi ø 4.00. Skewness (S) shows very small size to oversize which is between phi ø -1.00 to phi ø +1.00 and the value of Kurtosis (K) for this river is dominated by grain size mesokurtic and platikurtic. Therefore, the Slope Stabilization or river bank slope protection of River Chini area is proposed to reduce the river bank erosion and sediment production.