Environmental Scientist - TNPCB - Hydrosphere
Hydrosphere – Study
Notes
Unit I: Introduction to Environment (30 Questions) Environment: Components
– Segments – Atmosphere: Troposphere – Stratosphere – Mesosphere – Thermosphere
– Lithosphere: Crust – Mantle – Core – Hydrosphere:
Fresh water and saline water
Introduction
The Hydrosphere encompasses
all the water found on, under, and above the surface of the Earth. It includes
oceans, seas, rivers, lakes, glaciers, groundwater, and atmospheric water
vapor. Water is essential for all forms of life, and the hydrosphere plays a
critical role in shaping weather, climate, landforms, and sustaining
ecosystems.
Definition
and Components
Definition:
The Hydrosphere is defined as
the combined mass of water found on, under, and over the surface of a
planet.
Major Components of the Hydrosphere:
|
Component |
Percentage
of Total Water |
|
Oceans and Seas |
97.2% |
|
Icecaps and Glaciers |
2.0% |
|
Groundwater |
0.7% |
|
Lakes and Rivers |
0.01% |
|
Atmospheric Moisture |
0.001% |
Distribution of Water on Earth
- Saltwater (Oceans & Seas): ~97%
- Freshwater: ~3%, most of it locked in
glaciers and ice caps.
- Only about 0.3% of
freshwater is accessible for human use (in rivers, lakes, and
groundwater).
Oceans
and Seas
Major Oceans:
- Pacific Ocean – Largest and deepest.
- Atlantic Ocean – Second largest.
- Indian Ocean – Warmest.
- Southern (Antarctic) Ocean – Surrounds Antarctica.
- Arctic Ocean – Smallest and shallowest.
Importance:
- Regulate global climate and
temperature.
- Influence monsoons and
rainfall.
- Home to marine biodiversity.
- Source of food (fish) and
minerals.
- Routes for international trade.
Surface Water Bodies
Rivers
and Lakes:
- Essential for freshwater
supply.
- Used in agriculture, drinking
water, hydroelectric power, and transportation.
- Major rivers: Amazon, Nile,
Ganges, Yangtze.
- Largest freshwater lake by
volume: Lake Baikal (Russia).
- Largest freshwater lake by
area: Lake Superior (North America).
Wetlands:
- Marshes, swamps, and bogs.
- Act as natural water filters
and flood protectors.
- Rich in biodiversity.
Glaciers and Ice Caps
- Contain about 68% of Earth's
freshwater.
- Located primarily in Antarctica
and Greenland.
- Play a key role in reflecting
solar radiation.
- Melting glaciers contribute to sea
level rise and climate change.
Water in the Atmosphere
- Exists as water vapor, clouds,
and precipitation.
- Small in quantity, but crucial
for weather systems.
- Part of the hydrological
(water) cycle.
Groundwater
- Stored in the pores of soil
and rock formations (aquifers).
- A vital source of water for
drinking, irrigation, and industry.
- Overextraction leads to depletion
and land subsidence.
- Contamination from chemicals
poses a threat to health and agriculture.
The
Water Cycle (Hydrological Cycle)
The continuous movement of water
within the Earth and atmosphere through various processes.
🔹
Main Processes:
- Evaporation – Water changes from liquid to
vapor.
- Transpiration – Water loss from plants.
- Condensation – Water vapor forms clouds.
- Precipitation – Rain, snow, sleet, or hail.
- Runoff – Water flows over land into
rivers and oceans.
- Infiltration – Water seeps into the ground.
- Groundwater flow – Water moves underground.
🔹
Importance:
- Regulates temperature.
- Distributes nutrients.
- Maintains ecosystems.
- Supports agriculture and
industry.
Biological
Importance of the Hydrosphere
- Water is essential for all life
processes: digestion, circulation, photosynthesis.
- Aquatic ecosystems such as lakes, rivers, oceans
are rich in biodiversity.
- Regulates body temperature in
humans and animals.
- Acts as a solvent and
medium for biochemical reactions.
Role
in Climate and Weather
- Oceans absorb and distribute
solar heat.
- Evaporation from water bodies
adds moisture to the air, forming clouds and precipitation.
- Ocean currents (like the Gulf
Stream) regulate global weather patterns.
- Sea surface temperatures
influence phenomena like El Niño and La Niña.
Significance
of the Hydrosphere
|
Aspect |
Significance |
|
Ecological |
Supports aquatic ecosystems and
biodiversity |
|
Economic |
Basis for agriculture, fisheries,
transport |
|
Social |
Provides drinking water, hygiene,
recreation |
|
Climate |
Regulates temperature and weather
patterns |
Other
Topics
