| Summary: | 碩士 === 逢甲大學 === 水利工程與資源保育學系 === 102 === Rivers are steep with rapid flows in Taiwan due to the geographical reasons. Severe variations in a streambed may have negative effects on the safety and stability of hydraulic structures and land beside the river. For example, the foundations of bridge piers and levees may collapse due to severe scours. The flood disaster can be reduced if the riverbed variation tendency can be properly evaluated based on the field measurements. The objective of this study is to develop a durable and reliable measuring technique - water and soil interface monitoring system. Formulas for the prediction of general scour can be developed based on these field data. Hopefully, it can be served as a reference of structure design for relevant engineers in the future.
The results show that the scour depth can be accurately detected under different types of unsteady flows in the laboratory. The system is able to measure the back silting without digging the river bed. The instrument of water and soil interface was installed in the main channel of the Cho-Shui River downstream of Tzu-Chiang Bridge. The test result in the field shows that it can accurately detect the water level and the riverbed elevation. The water level obtained from the water and soil interface monitoring system is consistent with that measured by the Fourth River Management Bureau (WRA) of typhoon Soulik (2013). Although the water level had exceeded the maximum elevation of 12.767 meters, the riverbed was still detectable, and a scour depth of 1.12 meters was measured after 2 hours of observation. Overall, the system is feasible to measure the real time dynamic general scour depth of riverbed during a flood event.
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