GLAND, Switzerland – Protecting watersheds provides many of the world’s megacities with freshwater and saves billions of dollars.

This is according to a new compilation of case studies by International Union for the Conservation of Nature (IUCN), published on March 13, ahead of the World Water Forum which will run from March 16 to March 22, in Istanbul, Turkey.

The world’s oldest and largest global environmental network, IUCN, is a democratic membership union with more than 1,000 government and NGO member organisations, and almost 11,000 volunteer scientists and experts in some 160 countries. Its work is supported by more than 1,000 professional staff in 60 offices and hundreds of partners in public, NGO and private sectors around the world.

“Many of the world’s big cities have understood that protecting their catchment areas makes economic sense. Rather than chopping down the forests or draining their marshlands, they are keeping them healthy and saving billions of dollars by not having to pay for costly infrastructure to store water, clean it or bring it from elsewhere,” said Mark Smith, head of IUCN’s Water Programme, in a release to the media.

The Indonesian capital, Jakarta, gets its freshwater for free from some 60 rivers originating in the nearby Gunung Gede Pangrango National Park. The water is worth an estimated US$1.5 billion.

The Venezuelan capital, Caracas, relies on the rivers from Guatopo and Macarao national parks for its freshwater provision. “Today, those rivers continue to supply a constant flow of freshwater to the city’s five million inhabitants, consuming some 17 thousand litres of water per second,” the release noted.

Protecting freshwater sources also benefits nature. In and around South Africa’s Kruger National Park, better river management has helped improve water provision for some local rural communities, while at the same time preventing loss of aquatic life in the park.

“Kruger’s main five rivers have suffered from pollution and unsustainable water use upstream, which led to some of them drying up completely. After implementing a large river-related programme with the agriculture, forestry and mining industries, we have seen an improvement in flows. Previously disappeared species have recolonised, and fewer unnatural fish kills have occurred,” said Harry Biggs, programme integrator at South African National Parks and leader of IUCN’s World Commission on Protected Areas Freshwater Task Force.

During drier times, expensive arrangements like water transfers and trucking of water had to be made to meet basic needs of some rural communities living along rivers near the park, when they could no longer, as in the past, access water from rivers. For some of these communities, cleaner and more water is now available.