Submarine Canyons Geomorphology off the Shelf Edge on the Eastern Continental Margin of India
Abstract
Geo-scientific investigations over the continental margins have become the prime focus of the coastal states of developing countries given to their socio-economic and environmental importance. Accordingly, even if the margins were mapped to a certain extent in the past, these regions are often revisited for in-depth examination employing modern equipment. The advance high-resolution capabilities of today's swath surveying tools provide unprecedented information about the marine geo-morphology. In the present study, a multi-beam echo-sounder system (MBES) survey campaign was undertaken on similar grounds to map the central part of the Eastern Continental Margin of India, off Visakhapatanam. In the past, over five decades ago, a single-beam echo-sounder transect data was acquired in the same region during an International Indian Ocean Expedition (IIOE). The expedition then, had revealed the existence of submarine canyons from the paper chart bathymetric record, based merely on a single profile. Hence, the region was revisited by deploying modern high-resolution multi-beam swath mapping sonar to generate bathymetry of the region and map the extent of the canyons in three dimension. The reproduced geo-morphology revealed existence of a system of over half a dozen canyons, in addition to the three previously discovered canyons during the IIOE. The lengths of the canyons vary from 25 to 40 km and widths from 1 to 10 km. The maximum channel valley depth in the canyon system is observed to be 675 m. The thalweg slope of the canyons in general, is steeper towards the canyon head having slopes of the order of 1:6, which diminishes to 1:16 in the lower part of the channel. Based on the cross-sectional and planer-form of geo-morphological analysis, the numerous scours observed along the thalweg of these canyons designate them to be a part of an energetic and evolving canyon system. Moreover, today's MBES provides auxiliary data-set that are capable of revealing a plethora of scientific information beyond the general hydrography of the region. This facilitates extraction of geo-morphological characteristics of the canyons and the adjacent seafloor. One such characteristic signature investigated in the present study is the variation in backscatter return intensity of the seafloor extracted from the MBES data-set.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMOS13C1553M
- Keywords:
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- 3045 Seafloor morphology;
- geology;
- and geophysics;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4894 Instruments;
- sensors;
- and techniques;
- OCEANOGRAPHY: BIOLOGICAL;
- 4260 Ocean data assimilation and reanalysis;
- OCEANOGRAPHY: GENERAL;
- 4262 Ocean observing systems;
- OCEANOGRAPHY: GENERAL