UNDERSTANDING AND EVALUATING THE IMPACT OF HUMAN ACTIVITIES ON AQUATIC ECOSYSTEMS AND WATER RESOURCE MANAGEMENT METHODS

The use of water resources has increased exponentially over the last century, in line with rising population. At the same time, human activities – agricultural and industrial ones in particular – have had a significant adverse effect on the quality of fresh water and have degraded aquatic environments. Therefore maintaining the quantity and quality of water in order to meet human consumption needs and ensure that ecosystems can function is now a serious challenge.

For researchers, this means looking at the interactions between human activities and the resource system. These interactions are studied from the point of view of both quantity and quality, and through various disciplinary perspectives, to give us a better understanding of how water resources function intrinsically, the extent of changes and the issues relating to water management.

At the University of Geneva, research on the theme of water takes three main directions.

• First of all, looking at the behaviour of contaminants in natural environments, their entry into the food chain and the ways in which their effects can modify biotic communities.
• Next, evaluating the effect of restoring aquatic environments on the species living in them.
• Finally, focusing on analysis of political, legal and economic processes and of institutional dynamics.

In the early 21st century, sustainable use of natural resources and ‘energy transition’ – aiming to replace fossil fuels with renewable energies – are at the heart of global environmental concerns. 

Water occupies a very particular place in this picture, since – unlike other resources – it cannot be replaced by any other substance: it is the very source of life. Earth viewed from space is blue because 71% of its surface is covered with water. However, this is salt water, which represents 96.5% of Earth’s surface waters. Fresh water, vital for human life, is found mainly in underground waters and in frozen areas (permafrost, glaciers, permanent snow). Only a tiny fraction of the water that is present on the surface of Earth can be used to meet human needs directly.

It is estimated that, in 1900, humanity was consuming approximately 700 km³  of fresh water a year. By 2000, the quantity had increased to almost 5,000 km³  – seven times more. This is being used mainly for agriculture (70%) and industry (20%), since domestic use represents only 10% of global consumption, though these proportions can vary according to the climatic and economic situation in each region. The growth in world population, combined with more intensive use of water resources, is increasing the risks of chronic water shortage in many countries, thus heightening the intensity of rivalries (even conflicts) over use of the resource.

Problems relating to water quality must be considered alongside those of the quantity of water available. Many uses of water (agricultural, industrial, domestic) degrade it by introducing undesirable substances or components, thus making it unfit for human consumption. Historically, the earliest declines in water quality resulted mainly from faecal contamination of untreated wastewater. Even nowadays, almost two million people (90% of them children under 5) die every year from diarrhoeal diseases, 90% of which are attributable to the health impacts of poor-quality drinking water. Other adverse impacts on water come from agricultural inputs (nutrients, pesticides), industrial inputs (synthetic products, heavy metals, nanoparticles, heat) and domestic inputs (pesticides, fungicides, medicinal substances, toiletries and cosmetics, flame retardants, microplastics, etc.). As measuring instruments improve, more and more different substances are being discovered in water. For example, up to 2003, measurement revealed four or five organic substances (pesticides) in the waters of Lake Geneva, whereas there are now more than 50. To what extent do these adverse impacts reduce water quality? Are there acceptable concentration thresholds? What happens to these contaminants? What role do public policies play in this picture?

Continental waters are not just a resource for human beings: they also form aquatic ecosystems, the functioning of which is vulnerable to disruption induced by human activities.

Research into these environments focuses on the transport of contaminants in the aqueous environment, their transfer into the food chain, their impact on organisms such as algae, bacteria and invertebrates, the history of environmental contamination, the effects of remediation measures on the biodiversity of populations in these environments and the impact of transfer into the environment of pathogens and antibiotic-resistant bacteria from domestic and hospital wastewater.

A further aspect of the ISE’s research on environments in continental surface waters looks at the effects of climate change on the functioning of marine and freshwater ecosystems, particularly with regard to microbial diversity.  

Finally, analysis of resource management methods involves looking at water as a socioecological system. In this context, the ISE’s research interests include the analysis of international law, economic analysis and the analysis of institutional dynamics. A UNESCO Chair in Hydropolitics was established at the University of Geneva in March 2016, within the Institute of Environmental Sciences.