More Than Half of The World's Large Lakes Are Drying Up, Study Finds : Daily Current Affairs

Date: 22/05/2023

Relevance: GS-3: Biodiversity and Environment

Key Phrases: Climate change impact, Human consumption, Sedimentation, Rising temperatures, Pollution control, Ecosystem disruption.

Context:

  • A recent study has revealed that more than half of the world's large lakes and reservoirs have experienced a decrease in size since the early 1990s.
  • The research involved analyzing nearly 2,000 large lakes using satellite measurements, climate models, and hydrological models.

Do you know?

  • By 2080, the world's lakes will experience a temperature change of up to 6.7c caused by greenhouse gas emissions.
  • The Caspian Sea, holds the distinction of being the world's largest lake.
  • In 1981, Chilika Lake was designated as the first Indian wetland of international significance.
  • In India, the Wular Lake located in Jammu and Kashmir holds the distinction of being the country's largest freshwater lake.
  • Chilika Lake, located in the state of Odisha, holds the distinction of being India's largest saltwater lake.
  • Udaipur is renowned as the "City of Lakes" in India.

Key Highlights:

  • Over 50% decline: The study found that more than half of the world's large lakes and reservoirs have experienced a significant decline in water levels since the early 1990s. This decline poses substantial challenges for water availability and sustainability.
  • Climate change impact: Climate change emerged as the primary driver behind the shrinkage of these water bodies. Rising temperatures and changing rainfall patterns play a crucial role in the reduction of lake and reservoir volumes.
  • Human consumption: Unsustainable human use of water resources is a significant factor contributing to the decline. Excessive extraction for agriculture, industry, and domestic purposes depletes the water sources, exacerbating the problem.
  • Altered rainfall and run-off: Changes in rainfall patterns and increased run-off affect the replenishment of lakes and reservoirs. Reduced rainfall and increased evaporation rates diminish the inflow of water, leading to a decline in water levels.
  • Sedimentation: The accumulation of silt and other materials in lakes and reservoirs, reduces their capacity to hold water. This process further contributes to the decline in water levels.
  • Important freshwater sources, including the Caspian Sea and Lake Titicaca, have lost water at a cumulative rate of about 22 giga tonnes per year for nearly three decades.
  • Positive Changes: Water levels in approximately 25% of the studied lakes have increased, often due to dam construction in remote areas like the Inner Tibetan Plateau.

Role of Climate Change in the Shrinking of Large Lakes and Reservoirs:

  • Increased evapotranspiration:
    • With rising temperatures, there is an increase in evapotranspiration, which refers to the combined loss of water from both land surfaces and plants.
    • This higher evapotranspiration rate further contributes to the depletion of water in lakes and reservoirs.
  • Melting glaciers and reduced snowfall:
    • Climate change affects mountainous regions, leading to the melting of glaciers and reduced snowfall.
    • These changes impact the supply of freshwater to lakes and reservoirs, particularly those reliant on glacier meltwater or snowmelt.
  • Altered hydrological cycles:
    • Climate change disrupts the natural hydrological cycles, including the timing and duration of wet and dry seasons.
    • These alterations affect the inflow and outflow of water, further exacerbating the decline of large lakes and reservoirs.
  • Increased frequency of extreme weather events:
    • Climate change is associated with more frequent and intense extreme weather events such as droughts, heatwaves, and intense storms.
    • These events can lead to rapid water loss through evaporation, increased runoff, or damage to infrastructure, affecting the overall water balance in lakes and reservoirs.
  • Changing rainfall patterns:
    • Climate change causes uneven distribution of rainfall.
    • Reduced precipitation in certain areas or altered timing and intensity of rainfall events impact the inflow of water into lakes and reservoirs.
    • Results in decreased replenishment and declining water levels in affected water bodies.
    • Areas experiencing reduced rainfall face heightened risks of water scarcity and lake shrinkage.

Implications:

  • Water scarcity:
    • The decline of large lakes and reservoirs has severe implications for global water resources.
    • The reduced availability of freshwater impacts various sectors, including agriculture, energy, and human consumption.
    • It exacerbates water scarcity, leading to conflicts and socio-economic challenges.
  • Food security:
    • Agriculture heavily relies on water resources for irrigation.
    • As lakes and reservoirs shrink, the water supply for agricultural activities diminishes, impacting crop yields, food production, and food security.
    • This can lead to increased food prices and food shortages.
  • Energy generation:
    • Many hydropower plants depend on large lakes and reservoirs for water supply.
    • The decline in water levels affects hydropower generation, leading to energy shortages and an increased reliance on other energy sources, potentially impacting energy prices.
  • Ecosystem disruption:
    • Large lakes and reservoirs support diverse ecosystems, and their decline threatens the survival of aquatic plants and animals.
    • It disrupts the ecological balance, affecting biodiversity and the overall health of ecosystems.
  • Socio-economic impacts:
    • The decline of lakes and reservoirs directly affects human populations. Communities relying on these water bodies for drinking water, agriculture, and livelihoods face water shortages, increased competition, and potential migration.
    • This poses significant socio-economic challenges, particularly in regions heavily dependent on these water sources.

Significance of Sustainable Human Use in Addressing the Issue:

  • Reduction of water demand:
    • Unsustainable water consumption practices contribute to the decline of lakes and reservoirs.
    • Excessive water extraction for agriculture, industry, and domestic use strains water resources.
    • Promoting sustainable human use helps reduce the demand for water, alleviating pressure on these vulnerable water bodies.
  • Efficient water management practices:
    • Implementing water conservation measures to optimize water use.
    • Adoption of responsible irrigation techniques to minimize water wastage.
    • Recycling and reuse of water to maximize efficiency.
  • Pollution control:
    • Minimizing the introduction of harmful substances into lakes and reservoirs.
    • Reducing pollution from industrial discharge, agricultural runoff, and untreated wastewater.
    • Implementation of wastewater treatment and pollution control measures.
  • Long-term sustainability:
    • Sustainable human use practices ensure the long-term viability of lakes and reservoirs.
    • Balancing water extraction with the natural replenishment capacity of these water bodies.
    • Promoting responsible water management practices to maintain ecosystem health and biodiversity.

Conclusion:

  • The study's findings underscore the urgent need for sustainable water management and climate change mitigation measures.
  • Addressing the factors contributing to the decline of large lakes and reservoirs is crucial for ensuring water security, food production, energy generation, and the well-being of human populations worldwide.
  • Effective policies, conservation efforts, and international cooperation are necessary to mitigate the implications and safeguard global water resources.

Source: The Hindu

Mains Question:

Q. Critically analyze the role of climate change in the shrinking of large lakes and reservoirs. Evaluate the significance of sustainable human use in addressing this issue. (250 Words).