A study published in the Proceedings of the National Academy of Sciences revealed that changes in land use in watersheds have caused water treatment costs to increase by about half in nearly a third of the world's cities.
Generally speaking, the cost of urban water treatment depends on the quality of the water source. Urbanization has changed people's land use in urban watersheds, and it is difficult to establish a link between these changes and the cost of water treatment.
Robertmcdonald of the Nature Conservation Association and his colleagues rebuilt urban watersheds around the world by combining data on population growth and land use change, and using a newly constructed global data set detailing the location of water sources in 309 large cities. Models of degradation from 1900 to 2005.
The researchers also analyzed the water treatment technology of 264 water treatment plants and estimated the relationship between the decline in water quality and the increase in treatment costs. The authors say that for nearly one-third of the world's cities, the decline in water quality has caused treatment costs to increase by about half during those 105 years. In addition, 9 of the 10 cities involved in the study lost significant land cover due to agricultural and commercial development.