(Paris) The quality of fresh water, an essential and increasingly rare resource, is deteriorating, but it is difficult to know to what extent, due to a lack of data in countries where 3.7 billion people live, according to a UN Environment report published Wednesday.
“The poorest half of the world contributes less than 3% of global water quality data,” the UN laments in this report, which mentions in particular “4,500 measurements of lake water quality” by these countries, out of a total of 250,000 measurements worldwide.
As a result of this lack of data and these “low levels of monitoring”: “by 2030, more than half of humanity will live in countries that do not have sufficient data to inform management decisions related to combating drought, floods, the impacts of wastewater effluent and agricultural runoff”, according to the UN.
The analysis of the evolution of freshwater aquatic ecosystems illustrates this need for data.
Over the period 2015-2019, in 61% of countries, at least one type of freshwater ecosystem was in a state of degradation, including rivers, lakes and aquifers.
With comparable data, this percentage falls to 31% over the period 2017-2021, according to the report, a “positive trend”, underline its authors, who recall the establishment in 2015 by the United Nations of sustainable development objectives.
But if we take into account “the introduction of newly available data on water quality during the last observation periods”, this proportion of countries with degraded ecosystems stands at 50%, points out the UN.
In half of the countries, therefore, there is a decrease in the flow of rivers and a reduction in surface water, an increase in pollution and poorer quality water management, mainly in countries in Africa, Central and South-East Asia.
In order to improve knowledge of the state of ecosystems, the authors of the report recommend the development of long-term government-funded monitoring programs, the use of the population for data collection, in order to supplement these programs, as well as satellite observation data and modeling “to help fill the data gap.”