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An understanding of bridge scour mechanisms during floods in a fluvial river is very important for cost-effective bridge foundation design. Reliable bridge scour data for flood events are limited. In this study, field experiments were performed at the Si-Lo Bridge in the lower Cho-Shui River, the longest river in Taiwan, to collect scour-depth data using a sliding magnetic collar, a steel rod, and a numbered-brick column. By separating each scour component, a methodology for simulating the temporal variations of the total scour depth under unsteady flow conditions is proposed. The proposed total-scour model integrates three scour components, namely general scour, contraction scour, and local scour. The collected field data, comprising both general scour and total scour depths, are used to validate the applicability of the proposed model. Based on the peak flow discharges during floods, a comparison of the local scour depths calculated using several commonly used equilibrium local scour formulas indicates that most equations may overestimate the local scour depth. DOI: 10.1061/(ASCE)0733-9429(2008)134:6(810) CE Database subject headings: Bridges, piers; Scour; Floods; Measurements; Erosion; Deposition; Unsteady flow.

A critical concern regarding river bed stabilization and river engineering is the short-term general scour that occurs in a field setting far from a river-crossing structure or embankment during a typhoon-induced flood. This study investigated the improvement of existing techniques that have been used to measure river bed scour. One of these techniques is the numbered-brick column or scour chains method, in which only the maximum general scour depth of river bed is observed. A wireless tracer for monitoring real-time scour was set-up with a numbered-brick column and was employed to collect synchronous data. The proposed method was successfully used to observe both real-time scour and the maximum depth at flood peak. This observation was conducted at a steep gravel-bed reach of the Shuideliaw Embankment on the intermittent Choshui River in Central Taiwan during Typhoon Soulik, which occurred in 2013. Future studies must be conducted to complete the development of an automatic real-time scour and flood monitoring system for use in severe weather and flow conditions; this would facilitate the identification of river bed scour during conditions of unstable flow and the improvement of flood prevention engineering, bridge closure detection and emergency evacuation procedures. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Most rivers in Taiwan are intermittent rivers with relatively steep slopes and carry rapid sediment-laden flows during typhoon or monsoon seasons. A series of field experiments was conducted to collect suspended load data at the Tzu-Chiang Bridge hydrological station of the lower Cho-Shui River, which is a major river with the highest sediment yield in Taiwan. The river reach was aggrading with a high aspect ratio during the 1980s. Because of sand mining and extreme floods, it was incised and has had a relatively narrow main channel in recent years. The experimental results indicated that typical sediment transport equations can correctly predict the bed material load for low or medium sediment transport rates (e.g. less than about 1000 tons/day-m). However, these equations far underestimate the bed material load for high sediment transport rates. The effects of cross-sectional geometry change (i.e. river incision) and earthquakes on the sediment load were investigated in this study. An empirical sediment transport equation with consideration of the aspect ratio was also derived using the field data collected before and after river incision. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Obtaining discharge measurements during high flows is very difficult in steep rivers (slopes greater than about 0.1%) because of the highly unstable free surfaces and bed elevations. In this study, a portable flow measuring system with an acoustic velocimeter was developed. The proposed system has been proved to be better than existing systems for streamflow measurements in steep rivers. Field data collected by conventional velocimeters were analyzed, and compared with the flow measurements using the portable system with an ADP (acoustic Doppler profiler) or ADCP (acoustic Doppler current profiler). The effects of channel patterns on the applicability of the highly efficient discharge estimation method, as proposed by C.L. Chiu [An efficient method of discharge measurement in rivers and streams. In: Lecture of the workshop for development and application of discharge measurement in Taiwan. Taichung (Taiwan): National Chung-Hsing University, 1996. p. 55 [in Chinese]], were also discussed. In general, the method was applicable to higher flows where the measuring verticals were reasonably stable. [Copyright &y& Elsevier]

Because of climate change, remote mountainous areas are affected by heavy rainfall events, which frequently trigger severe natural disasters, such as mud flows, collapses, and landslides. These disasters severely affect the lives and properties of residents in remote mountainous settlements. Therefore, improving the function of immediate monitoring and early warning systems for disaster prevention is a crucial problem that is continuously studied. Improvements in natural disaster observation technology in remote mountainous areas and the continuous collection of on-site measured data can reduce risks for on-site researchers. This study, for the first time, expanded its application to the immediate monitoring of collapse and landslides by improving wireless tracer observation technology. This study focused on the remote mountainous areas of Kaohsiung City, South Taiwan. After numerous surveys, real-time monitoring, and station construction site evaluation, the observation location of this research was set to Dajin Bridge in Liugui District, Kaohsiung City. After selecting the monitoring site, various materials and equipment required for the monitoring station were prepared. According to burial operation procedures, a river channel real-time scouring monitoring station and landslides real-time monitoring station were established, and a remote wireless real-time data receiving system was developed. The results indicated no recent extreme rainfall events in the study area; thus, no scouring or landslides were observed; moreover, the lives and properties of the settlement residents in the study area were safe. The monitoring technology developed by the institute can continuously monitor environmental changes in the study area. [ABSTRACT FROM AUTHOR]