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High resolution bathymetric mapping of the Indian Exclusive Economic Zone Abhishek Tyagi, Dr. John Kurian P. National Centre for Antarctic and Ocean Research.

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Presentation on theme: "High resolution bathymetric mapping of the Indian Exclusive Economic Zone Abhishek Tyagi, Dr. John Kurian P. National Centre for Antarctic and Ocean Research."— Presentation transcript:

1 High resolution bathymetric mapping of the Indian Exclusive Economic Zone Abhishek Tyagi, Dr. John Kurian P. National Centre for Antarctic and Ocean Research Ministry of Earth Sciences (Govt. of India) Headland Sada, Vasco da Gama, Goa-403 804

2 Under the United Nations Convention on Law of the Sea (UNCLOS), the Exclusive Economic Zone or EEZ is covered by Articles 56, 58 and 59. The UNCLOS or the Law of the Sea Treaty, is the international agreement that defined the limits of the territorial seas of nations and the areas in which they could exploit marine resources. The EEZ is defined as that portion of the seas and oceans extending up to 200 nautical miles in which coastal States have the right to explore and exploit natural resources as well as to exercise jurisdiction over marine science research and environmental protection.

3 3 REGIMES CHART 1000 2000 3000 5000 4000 Oceanic crust (basalt) Shelf edge Geological slope GCCS (4) LLLaaannnddd Continental crust (granite) Base of the slope Geological rise GCHS (26-30) High Seas 3 Nautical Miles 12 Nautical Miles 24 Nautical Miles 200 Nautical Miles 0 Depth in meters OOOccceeeaaannn UNCLOS (3)UNCLOS (33) UNCLOS (57) UNCLOS (87,112-115) High Seas UNCLOS (79,113-115) Territorial Sea Contiguous Zone Exclusive Economic Zone UNCLOS (58, 113-115) LEGAL REGIMES : UNITED NATIONS LAW OF THE SEA CONVENTION 1982 (UNCLOS) GENEVA CONVENTION ON THE HIGH SEAS (April 29, 1958) (GCHS) GENEVA CONVENTION ON THE CONTINENTAL SHELF (April 29, 1958) (GCCS)

4 Continental Margins From the land, submerged edges of the continents : Continental shelf – nearly flat, gradual seaward slope; covered with sediments Continental slope – steeper seaward slope; submarine canyons Continental rise – 0.5° - 1° slope ; composed of sediments Main Regions include: Continental Margins, Deep-ocean Basins, Mid-ocean Ridges

5 Deep-Ocean Basins Beyond the continental margins, ocean floor deeper than 2000 m: Abyssal plains – very flat areas at depths of 3-5 km Seamounts – underwater volcanoes, > 1000 m high Deep-sea trenches – steep-sided, long, narrow depressions

6 Mid-Ocean Ridges Underwater mountain ranges that are the longest on earth Occupy 1/3 rd of the ocean floor Contain rift valleys at the summits as well as many fracture zones, where rocks have cracked and slid past one another

7 Bathymetry is Basic Information Bathymetry provides information about water depth Bathymetry gives a descriptive picture of the ocean bottom terrain, revealing the size, shape and distribution of seabed features APPLICATIONS: For Science Oceanography, geology, biology, ecology For Economics and Infrastructure Resource exploration, cable routing, shipping For Management and Policy Fisheries, Maritime Boundaries, Marine Protected Areas Defence & Sovereignty issues

8 HMS Challenger-first to study bathymetry in parts of all the oceans except the Arctic Ocean Achievements: the first systematic attempt to chart the basins of the world ocean 492 bottom soundings Echo sounder (also called SONAR) Invented in the 1920s Primary instrument for measuring depth Reflects sound from ocean floor

9 Echosounder Operation Positioning using GPS Uses acoustic energy (sound) Pulse of sound travels through the water column Lapse in time converted into distance (Source:

10 Technologies have evolved to survey the ocean floor more accurately & widely

11 Spaceborne Bathymetric Mapping Tools Airborne Shipborne 10,000m 2m NEARSHOREOFFSHORE barrier reef lagoonfringing reef Tide Gauge

12 Hull-mounted vs towed Hull-mounted (i.e., most swath bathymetry systems): Fixed mounted on the ship; don’t require repeated deployment Can collect data while ship is being used for other purposes (e.g., physical oceanographic cruise) Fast surveying (ship can travel at ~10 knots) Acoustically noisy (near-surface turbulence and ship noise) Resolution constrained by near-sea-surface location Hard to access for repairs, and Compatibility with certain hull shapes

13 Hull-mounted vs towed Towed (i.e., most sidescan sonar systems): Location of fish with respect to ship must be measured or calculated Deployment/retrieval, ship speed must be slow ~2 Knots Operate in quieter water at greater depth Easier to move from ship to ship Must be deployed each cruise Sidescan sonar Multibeam sonar (Source:

14 INDIAN EEZ MAPPING PROGRAMME  To prepare a comprehensive seabed topographic map for the entire EEZ of the country using the multibeam swath bathymetric systems. NCAOR Responsibilities  Bathymetric survey beyond 500m, data interpretation, analysis, maps preparation etc.  Archival of all data collected by the participating institutes. Participating Agencies  NIO, Goa- Shallow waters (West Coast)  NIOT, Chennai - Shallow waters (East Coast & Andaman region) Vessel’s utilised for Deepwater Survey ORV Sagar Kanya RV Sagar Nidhi RV Ak. N. Strakhov

15 Indian EEZ covers about 2.37 million km 2 12 th largest EEZ in the world

16 The MBES technology requires different set of instruments with different operating frequency and technique to undertake bathymetric surveys for shallow and deep water regimes and since the Indian EEZ is having a wide range of bathymetric depths (i.e., upto ~4000 m), the entire EEZ has been divided into two segments viz. Segment-I with areas having bathymetric depth less than 500 m, and Segment-II with areas having bathymetric depth more than 500 m. Technically, shallow waters, less than 500 m water depth need to be surveyed using higher frequency MBES systems while the deep-waters more than 500 m water depth need to be surveyed with lower frequency systems. To understand the source of sediment fluxes, their transport mechanisms and to assess the potential of seabed resources, sediment samples are also being collected in a systematic manner during the course of the surveys. Analysis of the sediment samples essentially aid to assess the potential resources as well as to reconstruct the palaeoceanographic conditions and paleoclimatic history.

17 Description Area (sq. km.) Total Area of Indian EEZ (Source: World EEZ-v4)2372298 Area with more than 500 m depth1875378 Area with less than 500 m depth496920 Area of EEZ around Mainland (East coast and West coast)1697775 Area of EEZ around Andaman & Nicobar Islands684933 Details of Indian EEZ areal extents Implementation Segment-I : Upto 500m depth Segment-II: Beyond 500m depth

18 Vessel ORV Sagar Kanya RV Sagar Nidhi RV-Akademik Boris Petrov RV-Akademik Nikolaj Strakhov Make L3-Comm. Elac-Nautik ResonAtlas ElektronikReson ModelSB3012Seabat 7150Hydrosweep-DS2Seabat 7150 Frequency of operation12 kHz12 KHz15 kHz12 kHz Number of Beams201Upto 88059 / 240 (HDBE)234 Swath CoverageUpto 5 x Depth Upto 3.5 x DepthUpto 5 x Depth Beam WidthUpto 140°Upto 150°Upto 120°Upto 150° Beam Width1°2°2.3°2° Depth of performanceUpto 11,000m Upto 10,000m/ 6000m Upto 10,000m Upto 10,000m/ 6000m Acquisition softwareHydrostarPDS2000Hydromap OnlinePDS2000 Post processingEiva NaviPacPDS2000Hydromap Offline PDS2000 Specifications of MBES used for deep water surveys In India, the first multi-beam ‘Hydrosweep-DS’ system was installed onboard Oceanographic Research vessel (ORV) SAGAR KANYA in 1990

19 VesselRV Sagar Sukti RV-Sindhu Sankalp CRV- Sagar Purvi CRV-Sagar Pachimi MakeKongsberg Reson ModelSimrad EM1002 8101 Frequency of operation95 kHz 240 kHz Number of Beams111 101 Swath CoverageUpto 7 x Depth Upto 7.5 x Depth Beam WidthUpto 150° Beam Width2° 1.5° Depth of performanceUpto 1,000m Upto 300m Acquisition softwareNeptune PDS2000 Post processingSIS, Cfloor PDS2000 Specifications of MBES used for shallow water surveys

20 During the course of the high-resolution multibeam bathymetric mapping of the Indian EEZ, several geomorphological, structural and tectonic features have been mapped including ridges, seamounts, knolls, abyssal hills, levees etc. Some of the known features are now mapped with enhanced accuracy and resolution, hence providing better ideas about geomorphic and evolutionary history. Integrated analysis of the bathymetric data, coupled with geological and geophysical information from the region would provide new insights into the regional tectonics, tectonic evolutionary history and basin evolution. Revealed presence of a new channel-levee system in the lower fan region of Bay of Bengal. Preliminary analysis of the data inferred that these submarine channel-levee systems have served as pathways for turbidity currents and other sediment-gravity flows to transport and deposit sediments from the continents to deep basins of the Bengal Fan. Parts of the Ninetyeast ridge and Laccadive ridge have also been mapped and better resolution geomorphologies of these sections have been prepared. THANKS Results

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