Water and Biodiversity

Start music   Jan 11 2017 || 1:24 PM

Water: A precious resource


International Water Conservation Efforts

World water day

  • Celebrated on the 22nd March is celebrated as the world water day
  • To attract the attention of everybody towards the importance of conserving water
  • The amount of water recommended by the UN for drinking, washing, cooking and maintaining proper hygiene is a minimum of 50 litres per person per day


International Year of Freshwater

  • Year 2003 was observed as the International Year of Freshwater
  • To make people aware of this dwindling natural resource


Water for life

  • United Nations has proclaimed the period 2005–2015 as the International Decade for action on “Water for life”


Forms of water

  • Solid form: As Ice and snow present in the poles, snow covered mountains & glaciers
  • Liquid form: Oceans, rivers, lakes ponds and underground
  • Gaseous form: As water vapour in the air


Groundwater as an important source of water

Water table

  • Deep underground, there is a level where all the space between particles of soil and gaps between rocks are filled with water.
  • The upper limit of this layer is called the water table
  • Water table level varies from place to place. It may even change at a given place due to certain factors


Recharging of water table

  • The process of seeping of water into the ground is called infiltration
  • The groundwater gets recharged by infiltration



  • At places the groundwater is stored between layers of hard rock below the water table.
  • This is known as an aquifer.


Depletion of water table

  • Water drawn from under the ground gets replenished by seepage of rainwater
  • Water table may go down if the water is not sufficiently replenished
  • This can happen due to many reasons:
    • Increase in population
    • Increase in industrial and agricultural activities
    • Scanty rainfall
    • Deforestation
    • Decrease in the effective area for seepage of water


Effective Water management Practices

  • Rainwater can be used to recharge the groundwater through rainwater harvesting
  • There is an old water storage practice called ‘Bawri’ which was a traditional way of collecting water
  • Farmers may use drip irrigation to deliver water directly to the bas of the plant




Forests: Our Lifeline



  • Branchy part of a tree above the stem is known as the crown of the tree



  • The branches of the tall trees resemble a roof over the other plants in the forest. This is called canopy



  • Trees have crowns of different types and sizes.
  • These had created different horizontal layers in the forest.
  • These are known as understoreys



  • The micro-organisms which convert the dead plants and animals to humus are known as decomposers


Significance of forests

  • Many food chains can be observed in forests, which ensure balance in the nature
  • They are called green lungs as they absorb CO2 and release O2
  • They increase the water table in the surrounding places
  • Many tribal people depend on forests for their livelihood
  • It is home to several species of plants and animals
  • They prevent widespread soil erosion by wind and water
  • The forest is a ‘dynamic living entity’, full of life and vitality



Wastewater Story


  • Cleaning of water is a process of removing pollutants before it enters a water body or is reused
  • This process of wastewater treatment is commonly known as “Sewage Treatment”



  • Sewage is the liquid waste released by homes, industries, hospitals, offices ets
  • It has high quantities of impurities also known as contaminants
  • It is carried from one place to another through a network of big and small pipes, called sewers, forming the sewerage
  • Sewage treatment is done in a treatment plant and consists of a number of steps


Wastewater Treatment Plant (WWTP)

Removal of large objects

  • Wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed
  • Water then goes to a grit and sand removal tank. The speed of the incoming wastewater is decreased to allow sand, grit and pebbles to settle


Removal of sludge

  • The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faeces settle at the bottom and are removed with a scraper. This is the sludge
  • A skimmer removes the floatable solids like oil and grease
  • Water so cleared is called clarified water


Treatment of Sludge

  • The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria
  • The biogas produced in the process can be used as fuel or can be used to produce electricity



  • Air is pumped into the clarified water to help aerobic bacteria to grow.
  • Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water
  • After several hours, the suspended microbes settle at the bottom of the tank as activated sludge
  • The water is then removed from the top


Treatment of Activated sludge

  • The activated sludge is about 97% water.
  • The water is removed by sand drying beds or machines.
  • Dried sludge is used as manure, returning organic matter and nutrients to the soil


Discharge of water

  • The treated water has a very low level of organic material and suspended matter
  • It is discharged into a sea, a river or into the ground