News Excerpt:

A report published in the journal Nature Water has revealed that the expansion of irrigated agriculture has increased global crop production but resulted in widespread stress to freshwater resources.

Key points of the report:

• More than half (52%) of the irrigation expansion has taken place in areas that were already water-stressed in the year 2000.
• India alone accounted for 36% of global unsustainable irrigation expansion.
• Existence of water stress suggests further depletion of streamflow and aquifers in these locations.
• The countries in which irrigation expanded the most were China (12.8 mha) and India (8.5 mha).
• A major reason behind this expansion was the increasing investment in irrigation projects to maintain food self-sufficiency.
• Over 90% of humanity’s consumptive water use is used for irrigated agricultural production.
• Irrigated areas account for 24% of global croplands.
• Roughly 40% of global food production is from irrigated croplands.
• These outputs were combined with information on green and blue water stress.
• Green water stress (GWS) refers to a situation when rainfall is insufficient to meet a crop’s water requirement and supplementary irrigation is needed.
• In the case of GWS, expansion of irrigation infrastructure can be a valuable strategy for buffering against variations in rainfall.
• Blue water stress (BWS), on the other hand, occurs when there is insufficient access to surface and groundwater resources, such as rivers, lakes, or aquifers, for irrigation purposes. 
• In BWS, expansion of irrigation infrastructure can lead to enhanced depletion of aquifers and streamflow. 

• Out of the total 65 million hectares of gross irrigation expansion:
• 1.1 million hectares took place in regions only experiencing blue water stress (BWS).
• 19 million hectares occurred in areas only facing green water stress (GWS).
• 31.2 million hectares were within regions experiencing both blue water stress (BWS) and green water stress (GWS).
• 13.9 million hectares were situated in regions with no water stress.

• Both types of stress can hinder agricultural productivity and pose challenges to water resource management.
• In countries such as Brazil, Indonesia, Peru, Italy and France AEI expansion was sustainable.

Global impact:

• For food-importing countries (for example, Saudi Arabia and South Africa), such a situation may cause local food production to falter and necessitate a growing reliance on food trade.
• For food exporters (for example, the US and Australia), continued unsustainable irrigation practices could force a reduction in food exports to continue to meet domestic food demand.

Conclusion:

The expansion of crop production via unsustainable irrigation practices impacts food self-sufficiency and global food security, notably with many nations dependent on food imports. Continuing irrigated agriculture in water-scarce regions raises the risk of freshwater depletion, potentially imposing physical and economic constraints on production levels.