Half of us live near fresh water
07.07.2011
Aalto University researchers’ recent global spatial data analysis reveals that over 50% of the world’s population lives closer than 3 km to the nearest river or lake. Majority of world’s population still lives on a walking distance from a river or lake, reveals a global analysis.
Despite the modern technologies, that enable transferring water over long distances to users, people still tend to live close to water. Aalto University researchers’ recent global spatial data analysis reveals that over 50% of the world’s population lives closer than 3 km to the nearest river or lake. Only 10% of the population lives further than 10 km away. Overall, only slightly more than 3 percent of the earth’s continental surface is covered by water.
- We found remarkable differences between regions and countries, says Matti Kummu, leader of the study.
Americans tend to live on average farther away from water than, say, Europeans. Researchers considered that this could be related to the fact that large American cities developed much later than many of the major cities in Europe. Early cities used rivers as transportation routes, dwells and sewers. By the time US cities developed, means of transporting people and water were more advanced.
Finland is called ''the land of thousand lakes” (187,888 lakes, to be exact), but Finns do not live closest to the water in the world. Average Finn lives 2.7 km from the nearest lake or river, much farther than for example Iraqi (2.0 km). In Europe, closest to the water live people in the Netherlands and Sweden (2.2 km). From all the countries, the people of Libya live, on average, the farthest from water (233 km).
Aalto University's research is the first of its kind in the world. For analysis purposes, researchers created a global grid at a resolution of 1 km x 1 km. By combining 15 global datasets, research team calculated water-related figures for each grid-cell and presented the results on world map. They also explored how the distance to water and different climatic variables (rainfall, temperatures, climate zone) correlated with population density.
Statistical analysis revealed that the distance to water explains population distributions only in the most arid zones. For example, in poor and dry North Africa, people are packed close to the water. Wealthy societies can afford advanced water supply systems and population could be located far away from watercourses. Still, the proximity of the water attracts people.
- In India, the distance to water is much more crucial for survival in everyday life than, for example, in Japan where it may have more aesthetic and cultural value, says researcher Matti Kummu.
The research project will bring new knowledge for global studies on development and climate adaptation. Nearly one billion people still live without improved sources (as in the WHO definition) of drinking water.
- It is one of the UN’s main development indicators. Still, distance to the water is missing from the criteria set, says Kummu.
Now, researchers use the same data with historical population density maps to explore how the average distance to water has changed over the last 2000 years.
- According to preliminary results people lived closest to the water in the 19th century. Now the distance seems to be growing, says Matti Kummu.
Researchers work in the Aalto University's multidisciplinary Water and Development -group. Group leader Professor Olli Varis is an internationally recognized expert in the field. The group’s recent work with water-related global problems includes research projects of the Mekong River, where hydropower construction and rapid population growth has generated huge environmental challenges.
Download research report freely online: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020578
Pictures:
Fig_S6_countries_median.pdf
diagrammi_water.png
Lisätietoja:
Matti Kummu
tutkijatohtori, vesitekniikka
Aalto University
School of Engineering
yhdyskunta- ja ympäristötekniikan laitos
tel. +358 9 470 23833
matti.kummu [at] aalto [dot] fi
Source: Kummu M, de Moel H, Ward PJ, Varis O (2011) How Close Do We Live to Water? A Global Analysis of Population Distance to Freshwater Bodies. PLoS ONE 6(6): e20578. doi:10.1371/journal.pone.0020578
Text: Petja Partanen
