Water Resources and Ecosystem Services of the Andean Altiplano: A Fragile Balance Threatened by Climate Change and Pollution

At an altitude of more than 3,800 metres, the Katari River basin in Bolivia stretches from the glaciers of the Cordillera Real to the shores of Lake Titicaca. Home to more than one million people, this region encompasses a wide range of ecosystems, including glaciers, rivers, lakes and high-altitude wetlands. These environments play a vital role in water supply, agriculture, fisheries and biodiversity conservation. However, their fragile balance is increasingly under threat.

In a study published in Science of the Total Environment, an international team from LMI ALTIPLANO, bringing together researchers in geosciences, climatology, hydrology, ecology, health and social sciences, presents a synthesis of more than fifteen years of research in the region. Coordinated by Stéphane Guédron (Geochemistry Team, ISTerre) and Dario Acha (Universidad Mayor de San Andrés, Bolivia), the review draws on approximately 80 scientific studies and examines how the impacts of climate change interact with those of human activities.

Climate change is causing glaciers to retreat rapidly, increasing evaporation and making droughts more frequent and longer-lasting. These changes are particularly affecting bofedales, wetlands characteristic of the high Andes that act as natural reservoirs: they store water during wet periods and gradually release it throughout the dry season.

These environmental changes are compounded by the effects of rapid urbanisation, mining and agriculture. In the urbanised part of the basin, particularly around El Alto, inadequate wastewater treatment infrastructure results in the discharge of wastewater containing high levels of organic matter, nutrients, metals and emerging contaminants (including antibiotics). These pollutants are carried by rivers into Lake Titicaca, with consequences for both ecosystems and human health.

The study highlights, in particular, the synergistic effects of climate change and pollution, which can trigger sudden environmental degradation, including eutrophication and massive algal blooms in Lake Titicaca, threatening local biodiversity.

In response to these challenges, the researchers emphasise the need to reduce pollutant discharges, protect wetlands and develop nature-based solutions, such as water filtration using plants. They also show that the sustainable management of these socio-ecosystems requires stronger governance structures that incorporate the needs and knowledge of local communities into decision-making processes, helping to build more resilient management systems.

References:

Guédron S. et al. (2026). Effects of climate change and anthropogenic pressure on water resources and ecosystem services in a high-elevation Andean socio-ecosystem (Katari basin, Lake Titicaca, Bolivia): A synthesis. Science of the Total Environment, 1053, 182339.