Cloud-seeding, physical transportation and wastewater management can help tap into millions of cubic kilometres of water, says new book by UN University
Air, continental shelves and even cargo ships contain millions of cubic kilometres of water that can help reduce shortage of water across the world for drinking, sanitation, agriculture and economic development, new book has claimed.
Unconventional Water Resources — compiled by experts at the United Nations University’s Institute for Water, Environment and Health (UNU-INWEH), UNU Institute for Integrated Management of Material Fluxes and of Resources and the UN Food and Agriculture Organisation, — has showcased the potential of resources such as offshore and onshore deep groundwater, irrigation water, municipal wastewater, and water vapour trapped in fog.
“These sources will be essential to building a future in arid areas,” UNU-INWEH Deputy Director Manzoor Qadir, also the book’s lead editor, said in a statement.
According to institute director Vladimir Smakhtin:
As climate change worsens and with population rising worldwide, water shortages are a top threat to human development and security, making this authoritative analysis of unconventional water resources both timely and important.
The book has hypothesised on the viability and offered strategies of five methods:
The authors advocated for enhancing rain via cloud-seeding: “Global research on cloud-seeding technology indicates that precipitation can be increased up to 15 per cent of the annual norm, depending on the available cloud resources and technical systems used.” They, however, acknowledged that greater research was needed on the variability of the technology in different areas.
Fog harvesting and micro-catchment rainwater harvesting have been marked as low-cost and low-impact methods. Efficient fog harvesting systems — wherein moisture in fog is collected through rocks, flora or mesh nets — can yield within 20 litres per square metre per day, for a decade. Only 70 sites have shown to be viable for fog harvesting.
Micro-catchments, on the other hand, have shown potential for households or farmlands in dry environments with low rainfall.
Icebergs, the world’s largest source for freshwater, have also been gaining attention in recent years. With climate change accelerating melting and breaking of huge chunks of ice at the poles, scientists, scholars and leaders — particularly in West Asia and Africa — have considered “towing” polar ice caps to water scarce countries for use.
In 2017, faced with massive water shortages, the United Arab Emirates proposed a plan to tow an iceberg into the country, but no action was taken on this front.
The other “transportable” resource is ballast water — fresh or saltwater held in the ballast tanks and cargo holds of ships to provide stability and manoeuvrability during a voyage.
Around 10 billion tonnes of ballast water is discharged globally every year; in accordance with international norms, this water needs to be desalinated. “As desalinization is applied as a ballast-water treatment, the end-product (desalinated water) is free of invasive aquatic organisms and unhealthy chemical compounds and is usable for other economic activities such as public water supply and irrigation,” the authors said.
The book noted that proper treatment of municipal wastewater — already underway in several countries — is a major resource of water for agriculture. It highlighted cities such as Chennai, Namibian capital Windhoek and Monteray (California, Unitd States) that have launched successful initiatives to treat wastewater to meet demand.
But it flagged a disparity in the management of this resource:
Today, around 70 per cent of the municipal wastewater generated in high-income countries is treated, but the ratio of water treatment falls to 38 per cent in upper-middle-income countries, 28 per cent in lower- middle-income countries, and 8 per cent in low-income countries.
Similarly, drainage water used in irrigation agriculture also has potential for reuse, but is hindered due to its high salinity. Careful management and promotion of salt-resistant crops can be the solutions for this.
The book also underscored that research has shown that continental shelves have around 5 million cubic km brackish water and 300,000-500,000 cubic km freshwater within their sedimentary deposits. Development of brackish water resources is already underway in countries in West Asia, Africa, Europe and the US and India.
The book has been released amid growing water scarcity globally. As many as 87 countries are projected to become water-scarce by 2050. Unconventional water resources mentioned in the book can provide major relief, provided the following strategies are followed:
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