SCITECH | One-third of all dryland regions have groundwater-dependent ecosystems, 53% of which in danger

By Jay Adrian Lotivio

A study published in Nature last July has reported that groundwater-dependent ecosystems (GDEs) exist in one-third of global drylands, of which 53% show declining groundwater trends, and only 21% are protected or maintained using sustainable water management policies.

Groundwater-dependent ecosystems range from springs, caves, karst systems, to deep-rooted plant communities. Rivers and lakes can also rely heavily on groundwater.

The study formed a high-resolution map of global GDEs using six years of satellite imagery from 2015–2020 and a random forest machine learning model. The study also examined the links between GDEs and human-factors such as cultural and socio-economic factors in the Sahel Region of Africa.

The study also reported that the severity of the threats to the GDEs varied, ranging from 90% of GDEs threatened in Europe, to 17% of GDEs threatened in Africa.

GDEs identified coincide with many of the world’s biodiversity hotspots, with examples such as in California, Mesoamerica, the Mediterranean Basin, Indo-Burma, Southwest Australia and New Zealand.

The map does not indicate GDEs that exist in wet environments, as there is a difficulty in finding the difference between water that comes from groundwater or precipitation in satellite-based datasets.

Whilst gaining a validation accuracy of 84%, the study also reports that characterizing these GDEs require extensive effort and on-site monitoring by countless experts, and the map only provides an indication of where these GDEs are the most likely to exist across global drylands.

The map is interactive and can be accessed through this link: https://codefornature.projects.earthengine.app/view/global-gde

Read the full study on Nature here: https://www.nature.com/articles/s41586-024-07702-8