Quantitative estimation of seafloor features from photographs and their application to nodule mining

Sharma, Rahul

doi:10.1080/10641199309379926

Cited by 23 publications

(20 citation statements)

References 8 publications

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“…In fact, the presence of polymetallic nodules in bulk quantity in the CIB itself points that the area receives very low sediments. This is further supported by photographs in the area that did not show the presence of ripple marks or scour marks on the rocks, crusts or nodules (Sharma 1993). This evidence may clearly rule out the possibility of strong currents and=or benthic storms in the CIB.…”

Section: Simulated Benthic Disturbance In the Central Indian Basin 369mentioning

confidence: 89%

First Phase Monitoring Studies of Simulated Benthic Disturbance Delineating Movement of Fine Particles in the Central Indian Basin

Valsangkar

2005

Marine Georesources & Geotechnology

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Benthic disturbance due to future deep-sea polymetallic nodule mining would involve extensive sediment plume generation and resedimentation on the sea floor. In order to evaluate the effects of resedimentation on benthic environment, the Indian Deepsea Environment Experiment (INDEX) was conducted in 1997, and pre-, and postdisturbance studies on grain size were carried out. The initial increase in clay content after the experiment, continued to increase further as measured in the first monitoring phase samples, 44 months later. Increase in clay-sized particles during monitoring-1 (M-1) was highest within the simulated (disturbed) zone and to the north of it, which is attributed to the combined effects of disaggregation, abrasion, and powderization of sediments during transportation. Due to this fractionation (breaking up), the particles appear to have remained in suspension over a prolonged period of time after they were discharged in the water column 5 m above the seabed during INDEX. The travel effects of INDEX plume appears to be localized and confined within and around the disturbed zone (DZ) as resettlement of fine particles from the benthic plume was traced up to 2 km south and 12 to 18 km north of the DZ. The evidence does not suggest the existence of strong currents and benthic storms in the CIB.Mining of deep-sea minerals, such as the polymetallic nodules, would disturb the sediments on the seafloor and create a large sediment plume similar to that from a benthic storm (Hollister and Nowell 1991). Deep-sea nodule mining activities are associated with erosion and deposition of the bottom sediments. If the nodules are screened close to the seafloor and the sediments are released from certain heights above the seabed, then the sediment plume would migrate in the direction dictated by bottom water currents (Murty et al. 1999), affecting the benthic community

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Section: Simulated Benthic Disturbance In the Central Indian Basin 369mentioning

confidence: 89%

First Phase Monitoring Studies of Simulated Benthic Disturbance Delineating Movement of Fine Particles in the Central Indian Basin

Valsangkar

2005

Marine Georesources & Geotechnology

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“…(Anonymous 1987). The areas covered during these experiments (0.32-10.8 km 2 ) also were much smaller than the estimated 300-km 2 area estimated to be mined every year during commercial mining (Sharma 1993). Similarly, the volume of sediment recovered during different experiments, 0.77 m 3 =min (NOAA-BIE), 1.17 m 3 =min (JET), 1.4 m 3 =min (IOM-BIE), and 1.35 m 3 =min (INDEX), range between 2-3.7% of the estimated volume of sediment (54000 m 3 =day, i.e.…”

Section: Comparison Of Impact Experiments To Large-scale Miningmentioning

confidence: 96%

“…According to Amos and Roels (1977), for every tonne of nodules, 2.5-5.5 tonnes of sediment will be resuspended. It is estimated that for the mining of 3 Â 10 6 t of nodules per year (of 8 kg=m 2 average abundance), the total volume of sediment to be resuspended will be 504 Â 10 7 m 3 , over an area of 600 km 2 (Sharma 1993). Experimental observations at INDEX site have shown that the transport of fine sediment (clay-sized particles) is generally restricted to the area in and around (within 20 km) the disturbance site and not to far away areas (45 km or more) (Valsangkar 2001).…”

mentioning

confidence: 99%

Deep-Sea Impact Experiments and their Future Requirements

Sharma

2005

Marine Georesources & Geotechnology

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In recent years, several experiments to assess the potential impacts due to deep-sea mining in the Pacific as well as the Indian Oceans have indicated the immediate changes and restoration patterns of environmental conditions in the marine ecosystem. The large volume of sediment ($ 500 Â 10 7 m 3 per year) estimated to be resuspended would be the major influencing factor in environmental impact in the mining area, leading to changes in availability of certain nutrients and composition of biomass, followed by gradual restoration. Important results have been obtained from these experiments, but in order to have a better understanding of the impacts and restoration processes, it will be necessary to improvise future experiments to resemble actual deep-sea mining in terms of scale and methodology.

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“…Major fe atures to be extracted from still photographs of se abed surface are the ( coverage and size distributions of manganese nodules Chautru, 1987;Handa, 1981, ) Hong, 1993Park, 1995;Sharma, 1989aSharma, , 1989bSharma, , 1993 . With the information extracted from othe r types of oce anographic data such as sonar data, the fe atures from photographs of the seabed surface can be utilized to select the potential mining areas.…”

Section: In Order To Develop the Mineral Resources Contained In Mangamentioning

confidence: 99%

An Image Analysis Technique for Exploration of Manganese Nodules

Park¹

1999

Marine Georesources & Geotechnology

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Quantitative estimation of seafloor features from photographs and their application to nodule mining

Cited by 23 publications

References 8 publications

First Phase Monitoring Studies of Simulated Benthic Disturbance Delineating Movement of Fine Particles in the Central Indian Basin

First Phase Monitoring Studies of Simulated Benthic Disturbance Delineating Movement of Fine Particles in the Central Indian Basin

Deep-Sea Impact Experiments and their Future Requirements

An Image Analysis Technique for Exploration of Manganese Nodules

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