India is fast hurtling towards acute water scarcity. The reasons are many. While groundwater overdependence, changing rainfall patterns, poor water management practices are to blame, recent research shows that poor water quality is also adding up to this scarcity while also threatening the health of populations.
The recent scare in Pune city, Maharashtra where mosquito swarms resembling tornadoes were cited over Mula Mutha river in Khadki area is evidence enough. While these turned out to be red bloodworms, relatively harmless relatives of mosquitoes, their presence indicated the very high levels of pollution of the river due to high levels of nutrients such as phosphates, nitrates in the waters due to release of untreated sewage. Increasing nutrient overloads in our rivers causing high pollution are also increasing vulnerability of populations to a range of water borne and vector borne diseases.
And water pollution is projected to increase in India in the future increasing pressure on the fast diminishing and over exploited water resources. A recent study titled 'A triple increase in global river basins with water scarcity due to future pollution' published in Nature Communications aimed at assessing future global clean-water scarcity in 2050 under climate change scenarios and socio-economic changes.
‘Clean-water scarcity’ was defined as the availability of surface water with acceptable quality and assessed with a water quantity-based and a water quality-based indicator. The study assessed >10,000 sub-basins worldwide based on their river discharges (water quantity) and nitrogen pollution levels (water quality) for 2010 and three scenarios in 2050.
Global water scarcity assessments have mainly focused on water availability. However, decreasing water quality caused by increasing and newly emerging pollutants are also becoming significant issues needing attention due to the threats posed by them to health and biodiversity. For example, agricultural intensification and urbanisation have added pollutants such as nutrients, pathogens, plastics, and other chemicals to the water bodies.
Among the pollutants, excessive nitrogen (N) in aquatic ecosystems can lead to harmful algae blooms, hypoxia, and fish kills and to deterioration in water quality and limit use of water for household use and drinking, thus aggravating water scarcity.
The study found that:
The study underscores the urgency of addressing water quality in future water management policies to align with Sustainable Development Goals.