The Study of Phong River Bank Erosion at Ban Nong Hin, Northeastern Thailand

Abstract

The river bank erosion is a major process to decrease a slope stability of the river bank, and then the slope can be failure. The Phong river bank at Ban Nong Hin, Northeastern Thailand is the research site in this study. The purposes of this study are to find and recheck the value of erodibility parameters of Phong river bank for predicting the erosion distance in the future. The erosion is occurred by the erosion rate (ɛ) is over than zero. The significant parameters are the boundary shear stress ( _o), the critical shear stress ( _c) and the erodibility coefficient (k_d). The water velocities are collected by the River Surveyor M9 equipment and the water-tele of the Electricity Generating Authority of Thailand. The field-testing results of the Submerged Jet Test are analyzed to predict the critical shear stress and the erodibility coefficient in each soil layers. The three differential methods for predicting the parameters are Blaisdell solution, Scour Depth solution and Iterative solution.Finally, the erosion distances are compared to the changed cross section of slope in 192 days. The erosion distance after surveying the new cross section is 3.73 m. The erosion distances of Blaisdell solution are 58.99 m. and 219.78 m., it’s an overprediction. The erosion distances of Scour Depth solution and Iterative solution are 0.00 m., it’s an underprediction. The probable factor that affected to this study is the variable density in each level of the soil layers. The test at the riverside and increasing the quantity may affect to predict the erosion distances more precisely.