Chapter 10 — Oceans and Life

Chapter 10, 'Oceans and Life', covers ocean floor features (submarine relief), movements of ocean water (waves, tides, currents), marine resources and the Blue Economy, maritime zones defined by UNCLOS, and early warning systems for tsunamis and cyclones.

Submarine relief refers to the physical landforms found on the ocean floor, such as the continental shelf, continental slope, abyssal plain, mid-ocean ridges, trenches, seamounts, and guyots.

Spring tides occur when the Sun, Earth, and Moon are aligned (on full moon and new moon days), producing unusually high and low tides. Neap tides occur during the first- and third-quarter moon phases when the gravitational pulls of the Sun and Moon act in different directions, resulting in a smaller tidal range.

Ocean currents are continuous streams of water flowing across the ocean surface in definite directions. They are caused by winds, the Earth's rotation (Coriolis force), differences in temperature and salinity, and the shape of continents and ocean basins. Warm currents flow from warmer regions; cold currents flow from colder regions.

The EEZ extends up to 200 nautical miles from a country's baseline, as defined by UNCLOS. Within this zone a country has special rights to use ocean resources such as fish, oil, and gas, though ships from other countries may still pass through peacefully.

The World Bank defines Blue Economy as 'the sustainable use of ocean resources to promote economic growth, improved livelihoods, and jobs, while preserving the health of the marine ecosystem.' It is linked to UN Sustainable Development Goal (SDG) 14: Life Below Water.

A network of seismic stations detects undersea earthquakes; Ocean Bottom Pressure Recorders (OBPRs) confirm tsunami waves; coastal tide gauges track sea-level changes; and alerts are sent via satellite, SMS, and coastal display boards to government agencies and the public.

UNCLOS stands for the United Nations Convention on the Law of the Sea. It defines maritime zones including territorial waters (12 NM), the contiguous zone (24 NM), the Exclusive Economic Zone (200 NM), and the high seas, establishing each country's rights and responsibilities.

GEMINI (GAGAN-Enabled Mariner's Instrument for Navigation and Information) is a handheld device that receives GAGAN satellite data and sends it to fishermen's phones via Bluetooth. It provides cyclone and tsunami warnings, fishing zone advisories, and other safety information in nine regional languages. Financial support for GEMINI is provided under PMMSY.

The Gulf of Khambhat has one of the highest tidal ranges in India at about 12 metres, making it one of the major potential tidal energy sites, along with the Gulf of Kutch and the Sundarbans.

A seamount is an underwater mountain of volcanic origin that rises from the ocean floor but does not reach the sea surface. A guyot is a flat-topped underwater mountain — a former seamount whose summit was eroded by wave action and later submerged.

The chapter identifies internal waters, territorial sea (up to 12 NM), contiguous zone (up to 24 NM), Exclusive Economic Zone (up to 200 NM), and the high seas (international waters covering about 64% of the world's oceans).

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The 2004 Indian Ocean Tsunami claimed around 2,30,000 lives and caused severe environmental damage across many countries bordering the Indian Ocean. In India, Tamil Nadu, Puducherry, Andhra Pradesh, Keralam, and the Andaman and Nicobar Islands suffered extensive damage. This disaster led many countries to establish tsunami early warning systems.