Navigating rivers and deltas
towards a sustainable future

Part 1

Rivers and deltas

Rivers and deltas are key systems that form the arteries of the earth, from the mountains to the sea, providing a multitude of opportunities for addressing global sustainability challenges, over the next decades. How we use, manage and invest in water management, adaptation, agriculture, infrastructure and urban development will determine the future lives of billions of people and the quality of our aquatic ecosystems.

Hotspot landscapes

Why rivers and deltas?

River basins and their deltas are hotspots of sustainable development and climate risks. They are hotspots because river systems and deltas are home to large and in developing countries growing populations that depend on the many ecosystem services these systems provide.

At the same time, population growth and ongoing economic development affect these services by disturbing the natural dynamics of rivers and deltas. Growing populations and increasing economic activities have increased flood risks, from either rivers or the sea, and are causing serious water pollution, which affects human health and biodiversity in the rivers, deltas and coastal seas. Numerous dams and sluices and increasing water use have disturbed and often diminished the flow of water and sediment from the rivers to the deltas. As a result, this has increased the pressure on transboundary collaboration in river basins.

This tool presents current and future challenges of rivers and deltas in more detail and explores various options for bending the trend in increasing pressures of socio-economic developments and climate change. This tool on rivers and deltas is a follow-up to The Geography of Future Water Challenges, which identifies four global hotspot landscapes, namely those with characteristic combinations of water- and climate-related risks and challenges.

River basins and deltas across the world

Source: Utrecht University, J.H. Nienhuis

Rivers stretch out from the smallest streams in the mountains to wide, estuarine outlets and deltas. While occupying only 0.8% of the Earth’s surface and 0.02% of available aquatic habitable volume, rivers and deltas are immensely important to humanity and sustainability. They provide water, fish, fertile soils and transportation routes for humankind, and host around 40% of all described fish species.

Urbanisation is growing faster in deltas than in any other geographical location. This puts delta systems under enormous pressures, from source to sea.

Sustainable development

The UN Sustainable Development Goals (SDGs) apply to all countries and have a timeline to be achieved by 2030. SDGs seek to eliminate extreme poverty and hunger; ensure health, education, peace, safe water and clean energy for all; promote inclusive and sustainable consumption, urban areas, infrastructure and economic growth; reduce inequality including gender inequality; combat climate change and protect seas and terrestrial ecosystems.

Water is linked to most of the Sustainable Development Goals, and this is particularly the case for river and delta systems. These goals cannot be achieved without adequate water management and adequate climate change adaptation. The extent to which these goals are achieved can be used as a framework for the sustainable development of river systems and deltas. Presently, the quality of most river basins and deltas is under enormous pressure, and conditions to make a transformative change are generally lacking and in need of attention. In this respect, much work still needs to be done, with sustainable development still being out of reach.

How is the human impact on rivers and deltas affecting achievement of the Sustainable Development Goals?

very positive positive little effect or high uncertainty negative very negative both positive and negative both very positive and very negative

Select a SDG in the wheel to read the impact below

SDG 1: No poverty


Many poor people are living in informal settlements (i.e. slums). Today, globally, these slums are home to about one billion people. Many slums are situated along rivers and in deltas in developing countries, where they are disproportionally affected by water- and climate-related disasters that keep their residents trapped in poverty.

The relevance of rivers basins and their deltas to sustainable development is linked with freshwater supply, flood protection, water pollution, human health and well-being, food and energy production, biodiversity and climate adaptation. Achieving the Sustainable Development Goals (SDGs) calls for a more central position of improved water management and adaptation to climate change in development strategies and investment decisions on river basins and deltas. A distinction can be made between two types of SDGs: conditional and outcome-related SDGs. The conditional SDGs must be achieved in order to also achieve the desired outcome (i.e. outcome-related SDGs). The conditional SDGs are (4) Quality education, (8) Decent work and economic growth, (13) Climate action, (16) Peace justice and institutions , and (17) Partnerships for the goals.

High urgency and a small window of opportunity

Available adaptation funds are not enough to bend the trend. Projected investments in urban development, infrastructure and agriculture should also be used for this purpose. The window of opportunity towards 2050 is small, and the urgency not to waste investments is high!

Mainstreaming adaptation in an integrated, inclusive and sustainable approach in rivers and deltas will ensure investment opportunities are used for a transformation that lasts, prepares for future challenges and creates value for people and planet.

Impacts of 1.5 °C and 2 °C global warming on natural, managed and human systems and on the ability to achieve the SDGs.

Source: IPCC

Climate change and our ability to achieve the Sustainable Development Goals are closely related; a large number of the targets of most SDGs could be undermined by climate change.

Climate change is already having large-scale impacts on ecosystems, human health and agriculture, which is making it much more difficult to achieve goals to eradicate poverty and hunger, and those to protect human health and life on land. Global warming is likely to reach 1.5 °C between 2030 and 2052 if it continues to increase at the current rate.

The increase in the risk of impacts for various sectors and for achieving the SDGs is presented in this IPCC graph. The grey horizontal bar represents the situation in previous years. Both mitigation and adaptation are needed. While many countries already face an adaptation deficit, serious efforts to adapt to the changing climate will be needed around the globe in any future pathway to reduce and manage the climate change impacts, as much as possible.

Projected investments per year, 2016–2050: a window of opportunity to ‘build back better’

Economic development picking-up after the COVID-19 crisis will result in investments of trillions USD per year in vital sectors, such as urban development, infrastructure and agriculture. The annual USD 0.1 trillion that will become available to support both mitigation and adaptation in developing countries based on the Paris Agreement compares poorly to this. These Paris Agreement adaptation funds will not be enough to bend the trend.

The projected investments in urban development, infrastructure and agriculture must be mainstreamed with water- and climate-related challenges in all development strategies. The level of urgency is high; the lead time of infrastructural developments is long and the window of opportunity to use projected investments effectively between now and 2050 is small. There will be no second chances to ‘build back better’.

Time to shift gear and change direction

For years, the World Economic Forum (WEF) has already been warning that natural disasters, water crises and the structural failure of climate change mitigation and adaptation are among the major global risks, and that we must act now to avoid severe consequences on a global scale.

Ever more people are sharing the sense of urgency expressed by the World Economic Forum; many conclude from the COVID-19 crisis that our relationship with the natural environment needs to change. The call for transformations and transformative approaches is everywhere, among a wide range of stakeholders and from global to local levels and scales.

The Global Risks Landscape 2020

Source: World Economic Forum, Global Risks Perception Survey 2019–2020

Worldwide, biodiversity is declining at an alarming rate, the fingerprint of climate change is detected more often in extreme weather events and disasters, increased heat and water scarcity affect the livelihood of millions, and accelerated sea level rise may submerge low-lying deltas and coastal zones.

Changing the way we live and work in river systems and in their deltas is urgently needed, and planned investments may provide a grand opportunity, provided a transformative pathway is followed. A good understanding of the system is at the core of making a shift towards sustainable development. In this tool, we show how river and delta systems work under natural conditions (part 2), how we have changed our rivers and deltas (part 2), what lies ahead in terms of further impacts under a business-as-usual scenario (part 2), and how we can bend the trend towards a more sustainable development (part 3).