Part 2 - Mapping hotspots

Flooding

Strong increase in potential flood risks

Flood risk increases mainly due to population growth and economic development.

Millions of people are living in flood-prone areas

x million people

Source: PBL

In 2010, around 1 billion people around the world were living in flood-prone areas, potentially exposed to either river or coastal flooding. This number is projected to increase to over 1.6 billion by 2050. Many more people are potentially exposed to river flooding than to coastal flooding.

River flooding

Share of the population annually exposed to river flooding increases, especially in Asia

Overall, more extreme precipitation will increase the risk of river flooding. Most of the people at risk of river flooding live in developing countries, especially in the South Asia and East Asia Pacific regions.

x 1000 people


What causes the change in exposed population between 2010 and 2050?
Select a region or a country from the drop-down menu on the right.

Share of the population annually exposed to river flooding in South Asia

x 1000 people

Source: Deltares, IVM

South Asia

Annually economic damage due to river flooding increases, especially in Asia

Without additional flood protection and following the projected strong increase in economic value in flood-prone areas, the focal point of damage due to river flooding will shift to Asia.

x USD million


What causes the change in economic damage between 2010 and 2050?
Select a region or a country from the drop-down menu on the right.

Annually economic damage due to river flooding in South Asia

x USD million

Source: Deltares, IVM

South Asia

Coastal flooding

Share of the population annually exposed to coastal flooding, high scenario climate change (RCP 8.5)

This is due to population growth, sea-level rise and land subsidence. Most of the people exposed to coastal flooding live in Asia, both in 2010 and 2050. Numbers are much lower than for river flooding.

x 1000 people


What causes the change in exposed population between 2010 and 2050?
Select a region or a country from the drop-down menu on the right.

Share of the population annually exposed to coastal flooding in South Asia

x 1000 people

Source: Deltares, IVM

South Asia

Annually economic damage due to coastal flooding, high scenario climate change (RCP 8.5)

As is the case for river flooding, the focal point of the damage from coastal flooding will shift strongly to Asia. Projected economic damage for Sub-Saharan Africa is lower for coastal than for river flooding.

x USD million


What causes the change in economic damage between 2010 and 2050?
Select a region or a country from the drop-down menu on the right.

Annually economic damage due to coastal flooding in South Asia

x USD million

Source: Deltares, IVM

South Asia

Urbanisation changes flood vulnerability

By 2050, 70% of the world population is projected to live in an urban environment. The global urban area is expected to expand by more than 70%, for a large part in riparian and coastal areas, and in deltas.

Cities with millions of inhabitants will continue to grow between now and 2050

Population in cities in 2010 and 2050

Source: PBL

Fast urban growth, more than doubling city sizes, occurs especially in the developing countries of East and South Asia and Sub-Saharan Africa.

Risks for people are unequally distributed

Source: PBL

Risks for people are unequally distributed. While the developed countries will face most of the economic damage, the majority of people at risk live in developing countries. The number of people at risk will increase more for the developing than for the developed countries.

Informal settlements are the most exposed to flooding

This illustration shows that informal settlements along a river get flooded when the river water level rises whilst formal settlements stay dry because they are built on higher ground.

Especially in developing countries, the inhabitants of informal settlements in cities make up more than 50% of the urban population.

Water- and climate-related disasters disproportionately affect people living in informal settlements.

Flood protection pays off

There are several ways to reduce flood risk. Investments in levees, dykes and storm surge barriers, as well as taking flood risk into account in spatial planning and building codes, will reduce both economic risk and the risk of large numbers of casualties.

Flood protection strongly reduces population exposed to river flooding

This graph shows that current flood protection has reduced the number of people annually exposed to river flooding globally from 150 to 40 million. The graph also shows that this number may increase from 40 to 110 million in 2050 without adaptation to climate change. With adaptation, this number would only rise to 65 million, however. In fact, this number would drop to less than 7.5 million people if flood protection of cities would be raised up to at least a once-in-a-hundred-years flood probability level.

Source: Deltares, IVM

Without any protection against flooding, about 252 million people would be exposed to river flooding, each year, based on current population numbers.

Actual protection levels, however, result in a substantial decrease in the number of people exposed, annually. An estimated 65 million people are exposed to flooding, each year, based on current levels of flood protection.

If current protection levels are maintained, the annual number of people exposed to flooding will more than double, by 2050.

If we adapt flood protection standards to climate change we can reduce this number to 108 million.

The figures about river flooding as published in ‘The Geography of Future Water Challenges’ (2018) are updated based on an improved version of the flood risk model GLOFRIS which includes:

  1. An improved version of the global hydrological model PCR-GLOB-WB with a higher resolution.
  2. An improved bias-correction method based on flood volumes.
  3. An improved version of the FLOPROS global database on flood protection.
  4. An improved dataset of the 2UP global urban development model, improving the exposure data (population and GDP).

We can even reduce this number to less than 7.5 million by increasing the protection of cities to a flood probability standard of 1:100–1:1000.