Abstract
The construction of fully closed check dam (CD) is a conventional flood prevention mechanism implemented on rivers. Fully closed CDs trap large amounts of sediments in rivers to stabilize the river slopes and control erosion. However, fully closed CDs cannot selectively trap sediment and may easily overflow, causing them to losing their ability to mediate and hold sediments. Previous studies proposed the concept of “breathable CDs”. The researcher introduced metal slit dam (SD) that could be assembled and disassembled quickly and conveniently. Once a CD reaches maximum capacity, operators must ensure that the water channels of the dam are free from blockage. Moreover, they must inspect the internal accumulation conditions of the dam periodically or immediately following heavy typhoon rains. When necessary, either the sediment buildup in the upriver blockage must be cleared, or the transverse structure of the dam must be removed to allow fine particles to be discharged along with a moderate amount of water. These actions can free up the sediment-storing capacity of the dam for the next heavy typhoon rains. In addition, operators should also inspect the damages inflicted on the dam, such as erosion, wear and tear, and deformation conditions. Damaged components should be disassembled and repaired if possible, or recycled and reused. The present study performed channel tests to simulate closed CDs, SDs, steel pipe dam (SPDs), and steel pipe plus slit dam (SPSDs) for 50-year and 100-year frequency floods. Results were then analyzed to determine the sediment trapping (ST) effects of various CDs, the effects of “adjustable CDs”, and the changes of moderated riverbeds.
Highlights
Taiwan is located at the boundary between the Eurasian Plate and the Philippine Sea Plate
According to the closed check dam (CD) simulation results, the sediment volume measured on the riverbed in a recurrence interval of 50 years was significantly greater than that of a 100-year
Since the slit dam (SD) is a form of open CD and its trapping area decreases concurrently with the increase in opening size, the sediment trapping (ST) effects of the SD were significantly lower than the closed CD
Summary
Taiwan is located at the boundary between the Eurasian Plate and the Philippine Sea Plate. Excessive rainfall often causes flooding and landslides in many areas of Taiwan. Flood prevention mechanisms must be established in at river locations to reduce the threat of river sediments. The construction of fully closed check dam (CD) is a conventional flood prevention mechanism implemented on rivers. Closed CDs trap large amounts of sediments in rivers to stabilize the river slopes and control erosion [1]-[3]. Fully closed CDs cannot selectively trap sentiment and may overflow, causing them to losing their ability to mediate and hold sediments. If the riverbed continues to elevate each year, the flood area of the river would continue to expand downriver, where numerous densely populated settlements and tourist locations are located, causing irreparable damage to people, farmlands, and private buildings
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