Shrinking of lakes worldwide

Shrinking of lakes worldwide

Subject: Geography

Section: Places in news

Context:

More than 50 percent of the world’s largest lakes and reservoirs have shrunk over the past three decades, also more than half of the reservoirs  located in peninsular India have witnessed substantial water storage decline. Moreover among the affected among natural lakes in India is Tso Moriri.

Causes

57 percent of the net decline in the water quantity in natural lakes is due to unsustainable consumption of water like in Aral sea, and also due to increasing and potential evapotranspiration(PET)-loss of water due to both evaporation and transpiration-with the latter two indicating the role of climate change(ex. Lake Kara Bugaz).Besides this two-thirds of all reservoirs have experienced significant declines due to sedimentation.

The Aral sea dried up.

Consequences

Two billion people, a quarter of the global population, depend on lakes for freshwater will be severely affected. Hydropower generation will be affected. The reduced size of these lakes not only results in environmental degradation but also disrupts the water and carbon cycle by rising water temperature which now starts emission of Carbon dioxide. The lakes encroached upon in India, especially in urban areas leads to incidence of Urban flooding as no lake is there to act as flood buffer(Ex Bangalore).

How to conserve

Lakes should be managed in integrated manner. Steps like restrictions on water consumption and climate mitigation to bring down global temperatures are some of the ways to conserve them. This will also help in reducing sedimentation in reservoirs as the rate of sedimentation is linked to climate change- it increases when there is extreme precipitation, as well as land disturbance such as wildfires, landslides, deforestation.