From Continental Shelf to Slope: Mapping the Oceanic Realm
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This volume covers multi-disciplinary Research and Development contributions from Europe, Asia and North America on geology, geophysics, bathymetric and biological aspects, towards data sampling, acquisition, data analysis and its results, and innovative ways of data access. It also presents the development of processes to map, harmonize and integrate marine data across EEZ boundaries, an impressive example of which is the European EMODnet (European Marine Observation and Data network) initiative. EMODnet assembles scattered and partially hidden marine data into continentally harmonized geospatial data products for public benefit and increasingly within overseas collaboration. The volume also aims to shed light on an evaluation of biological and mineral resources and environmental assessments at continental shelf to slope depths. Western Pacific examples provide excellent case studies for this topic. Mapping of the Ocean Realm is not only for scientific purposes, but also for the people who live by the seas. Communication amongst scientists and multiple stakeholders is essential for living sustainably with the seas. In this volume we encourage dialogue amongst all the stakeholders.
Geological controls on dispersal and deposition of river flood sediments on the Hidaka shelf, Northern Japan
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Published:September 07, 2022
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CiteCitation
Ken Ikehara, Hajime Katayama, Tsumoru Sagayama, Tomohisa Irino, 2022. "Geological controls on dispersal and deposition of river flood sediments on the Hidaka shelf, Northern Japan", From Continental Shelf to Slope: Mapping the Oceanic Realm, K. Asch, H. Kitazato, H. Vallius
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Abstract
The distribution and characteristics of marine surface sediments are a basic marine geological information. Large river floods are a frequent natural hazard that transport substantial terrigenous sediments into the marine environment. In August 2003, TY ETAU (0310) caused heavy rainfall in the southern coast of Hokkaido, north Japan, where some mountainous rivers in the Hidaka region flooded. Two deposition modes for the 2003 flood sediments can be identified by comparing the pre- and post-flood surface sediment distribution. Shore-normal shallow depressions off the mouth of the Saru and Atsubetsu rivers served as channels for the discharged floodwater preventing dispersion and maintaining the necessary water density to transport the materials as density bottom currents. This action also promoted long-distance transport of flood materials across the continental shelf. Absence of depression on the inner shelf off the mouth of the Niikappu and Shizunai rivers may have dispersed floodwaters near the river mouth and deposited the flood materials close to the shore. Marine geological mapping suggests that the differences in submarine topography (the presence or absence of shallow depressions) are closely related to the regional geological structure. Thus, submarine geology is a controlling factor of the seafloor environments influenced by the river flood.
- Asia
- bottom features
- channels
- coastal environment
- continental shelf
- controls
- cyclones
- deposition
- depressions
- discharge
- event stratigraphy
- Far East
- floods
- fluvial environment
- fluvial features
- geologic hazards
- Hidaka Japan
- Hokkaido
- hydrology
- Japan
- marine environment
- marine geology
- marine sediments
- natural hazards
- ocean floors
- rainfall
- rivers
- sediment transport
- sediments
- shorelines
- storms
- stream sediments
- submarine environment
- terrigenous materials
- transport
- typhoons
- Saru River
- Niikappu River
- Shizunai River
- hyperpycnal flow
- Atsubetsu River