An Exploration of the Role of Mountain River Sinuosity in Landscape Dynamics

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We have recently discovered that typhoon activity is recorded in a measurable way in the shape of mountain landscapes. We have found that typhoon strike frequency correlates well with the sinuosity of bedrock rivers, as does the relative frequency of extreme rainfall and flood discharge. This observation points to a fundamental climatic control on landscape dynamics, which we intend to pursue in detail in this project. Our focus will be the mountain rivers of Japan and Taiwan, whose landscapes together span a broad climatic range from the typhoon-dominated tropics to the temperate mid-latitudes, thereby providing a broad parameter range for study of the climatic effects. We will examine the morphology of these rivers at exemplary locations to gather a database of reach sinuosity, cross-channel morphology, hydrology and bedrock strength. With the help of these data, we will establish the respective roles of bedrock erodibility, sediment armoring and discharge statistics on sinuosity evolution. At the same time we will pursue theoretical development of a reach-scale model of sinuosity growth and reduction. Our ultimate aim is demonstrate the importance of flood variability and channel mobility in the evolution of mountain landscapes.The project will help to foster collaboration among scientists and engineers at universities and research agencies in the US, UK, Japan and Taiwan. It will support the involvement of one graduate student. Our anticipated insights into the effects of typhoon-driven floods will be of interest both to geoscientists across a range of disciplines and to those concerned with natural hazards and civil defense in environments subject to frequent tropical cyclone strikes.Cofunded by the Office of International Science and Engineering, NSF.