The role of the Global Groundwater Monitoring Network (GGMN) in advancing a global groundwater assessment based on in-situ data

Groundwater, a critical component of the Earth's hydrological cycle, plays a pivotal role in sustaining ecosystems, supporting agriculture, and ensuring water security worldwide. Understanding the dynamics of groundwater is crucial for effective water resource management, especially in addressing the interconnected challenges of water scarcity and climate change impacts.

Groundwater monitoring data, including levels, are frequently dispersed among institutions, even within a single country, presenting challenges in accessibility and availability. The process of harmonizing this data is intricate and often demands a substantial investment of time. Moreover, the data quality is dependent on the particular source and may exhibit considerable variability.

The Global Groundwater Monitoring Network (GGMN) Programme, managed by the International Groundwater Resources Assessment Centre (IGRAC), is dedicated to collecting and disseminating updated groundwater level data from national authorities. The mission of GGMN is to facilitate the accessibility of groundwater monitoring data and information, supporting IGRAC’s efforts to provide valuable insights into the global groundwater status and trends.

In 2023, data from GGMN played a pivotal role in assessing the status and trends of groundwater in ten countries, contributing for the first time to a preliminary assessment of groundwater for the World Meteorological Organization's (WMO) "State of Global Water Resources 2022" report. In 2024, these efforts continue with an enhanced methodology to understand trends, encompassing a broader range of countries for a more comprehensive assessment.

The collective effort of collecting data for GGMN and utilizing it for the WMO report aims to produce a robust global groundwater assessment based on in-situ data. This assessment will serve as a valuable benchmark for comparison against global models and other products, such as those derived from satellite data like GRACE. The in-situ data also holds immense utility for the scientific community, providing a means to validate and strengthen existing models, ultimately contributing to a more accurate understanding of global groundwater dynamics.