On International Day of Forests (21 March), we celebrate the many ways in which forests sustain and protect us. The following day is  World Water Day, where we explore global water challenges and solutions. Despite their proximity on the calendar, these two international days are only distant cousins in practice. Only a tiny fraction of national biodiversity plans consider the impact of forests on water supply, and only a fraction of national water plans place ecosystems at their centre. This is unfortunate, since nature can play a key role in securing water for the future.

Global water crisis, forest crisis

Our global rate of water consumption is unsustainable – we consume three times more per capita than we did a century ago, and demand will increase by more than 50 percent by 2030, to a level 40 percent above existing water supplies. At the same time, more than 40 percent of the world’s watersheds are facing moderate to high levels of degradation, and we are losing 18 million hectares of forests every year.

Crisis for cities and communities

The water crisis has profound impacts on cities; Cape Town is struggling to push ‘Day Zero’ into the future,  but it is not alone. Cities like São Paulo are not only facing risks of water crises in the future, but rather live with them on and off. Other cities like Bangalore, Beijing, Cairo, Jakarta, Moscow, Istanbul, Mexico City, London, Tokyo and Miami, home to more than 150 million people combined, are likely to face water crises by mid-century. This water crisis, which disproportionately affects rural and urban poor, as well as women and girls, profoundly compromises our ability to achieve the Sustainable Development Goals, especially food security, energy and economic growth, and it can foster corruption, inequality and political instability.
 

Nature-based solutions for water – taking action

Nature-based solutions can help secure water for the future, and forests have a key role to play. A third of the world’s largest cities depend heavily on forested protected areas for their primary water source. Forests regulate water flow, recharge aquifers, prevent sedimentation and filter contaminants.

There are a number of new publications that highlight nature-based solutions for securing water, including the new World Water Development Report coauthored by UNDP and launched this week at the World Water Forum in Brasília.

Governments are also beginning to recognize the value of forests in securing water. For example, Dar es Salaam in Tanzania has for decades faced annual shortages as the flow of its main source of water, the River Ruvu, has huge seasonal fluctuations. These shortages may be compounded as total flows of the river are dramatically falling. However, by improving land management and especially forest cover, the seasonal fluctuations might stand to be reduced for the benefit of the city. A new partnership between UNDP, NASA, and six universities has mapped the extent of forest cover, forest loss and protected areas within the source watershed, and the results are alarming - about 10 percent of the forest cover has been lost since 1997, and protected areas cover only about a quarter of the watershed.

UNDP is taking action. UNDP Tanzania, in partnership with the Global Environment Facility and the Ministry of Water and Irrigation of Tanzania, has introduced a programme on ‘Securing Watershed Services through Sustainable Land Management in the Ruvu and Zigi catchments. The programme aims to implement sustainable forestry and farming. If the project succeeds, it will increase water quantity and quality by 10 percent by the year 2020.

This example could be replicated around the world – a recent report shows that more than 3,200 of the world’s cities could significantly improve their water security by implementing nature-based solutions for water, affecting more than 700 million people, at a cost of less than US$2 dollars per person.

It is time to take action. Nature-based solutions are a proven, low-cost strategy for securing water. The United Nations has committed to focus on water for a decade (2018-2028). On 22 March  – World Water Day – the UN is launching the International Water Action Decade. Let’s use this opportunity to firmly place forests and other ecosystems at the centre of our national and local water strategies.