Shifting to millets increases groundwater recharge: Study

According to a new study, Switching from rice to pearl millet (bajra) and sorghum during the Kharif season and shifting from wheat to sorghum (jowar) in the Rabi season could lower water consumption in the Indo-Gangetic Plains (IGP) by 32 per cent and boost farmers’ profits by 140 per cent.

About the Study:

• Six researchers from the Indian Institute of Technology Bombay, University of Delaware, Columbia University and Yale School of the Environment analysed crop shifting’s prospect in 124 districts of three states: Uttar Pradesh, Bihar and West Bengal — covering the upper, middle and lower Ganga basin in the agricultural belt of India.

• Need: The Ganga basin has seen significant groundwater depletion in recent years, raising questions about the sustainability of present agricultural practices.
  • Among the solutions proposed to address this unsustainable water consumption, crop switching has received growing attention.
• The study discussed that the cereal crops (rice, wheat, maize, bajra, sorghum and barley), which cover 52 per cent of the total crop area accounts for 50 per cent of the total water consumption in the three states of the IGP region.
• They also highlighted that continuing with the same crop with drip irrigation improves net groundwater recharge by 34 per cent, whereas changing crop practices improves net recharge by 41 per cent.

Irrigation and declining groundwater:

• Groundwater depletion in India is a major concern because it is the primary source of drinking water.
• Some of the main causes of groundwater depletion in India include over-extraction of groundwater for irrigation, urbanisation, and climate change.

Major Causes of Groundwater Depletion in India:

• Over-extraction of Groundwater for Irrigation: Irrigation accounts for around 80% of total water use in India, and much of this water is sourced from groundwater.
  • As demand for food continues to grow, more and more groundwater is being extracted for irrigation, leading to depletion.
• Climate change: Rising temperatures and changing precipitation patterns can alter the recharge rates of groundwater aquifers, making them more vulnerable to depletion.
  • Draughts, flash floods, and disrupted monsoon events are recent examples of climate change events that are placing pressure on India's groundwater resources.
• Poor Water Management: Inefficient use of water, leaky pipes, and inadequate infrastructure for capturing and storing rainwater can all contribute to groundwater depletion.
• Decrease in Natural Recharge: The natural recharge of groundwater aquifers can be decreased by factors such as deforestation, which can lead to soil erosion and reduce the amount of water that is able to seep into the ground and replenish the aquifers.

Impacts:

• Water Scarcity: As groundwater levels drop, there may not be enough water available for domestic, agricultural, and industrial use. This can lead to water shortages and conflicts over water resources.
• Land Subsidence: When groundwater is extracted, the soil can become compacted, leading to land subsidence (the sinking or settling of the land). This can cause damage to infrastructure, such as roads and buildings, and can also increase the risk of flooding.
• Environmental Degradation: Depleting groundwater can also have negative impacts on the environment. For example, when groundwater levels drop, it can cause saltwater intrusion in coastal areas, leading to the contamination of freshwater resources.
• Economic Impacts: Groundwater depletion can also have economic impacts, as it can lead to reduced agricultural production and increased costs for water treatment and pumping.
• Lack of Depletion Data: Indian government regulates groundwater exploitation by "notifying" highly overexploited blocks in water-stressed states.