Interaction between weathering-erosion and riverbed deformation in a bedrock channel

2014 Fiscal Year Final Research Report

• Project/Area Number: 25820233
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Hydraulic engineering
• Research Institution: Public Works Research Institute
• Principal Investigator: INOUE Takuya 独立行政法人土木研究所, 寒地土木研究所, 研究員 (20647094)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 岩床侵食 / 乾湿風化 / 水路実験 / 粗度 / 砂礫被覆

Outline of Final Research Achievements

The typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the erosion rate of the material when subjected to impacts of moving sediment. The areal fraction of bedrock covered by alluvium is typically modeled as a function of relative sediment flux (sediment supply rate over bedload transport capacity), yet little is known about how the bedrock roughness affects the cover fraction.
In this study, we conducted laboratory experiments to develop an understanding of how weathering of bedrock affects the rock tensile strength and the bedrock erosion rate. Next, we performed flume experiments under varied sediment supply rates and bedrock surface topographies. We then developed a physically based model for predicting the cover fraction in consideration of the relative roughness (bedrock roughness over grain size), and tested the sensitivity of the model to changes in bedrock relative roughness and relative sediment flux.

Free Research Field

工学