Screen capture of IGRAC’s GLobal Groundwater Monitoring Network
Using AQUASTAT to find data on groundwater withdrawal
Groundwater level measurements give the best indication of the quantitative state of a groundwater system. However, installation and maintenance of observation wells is relatively expensive. Electromagnetic sensing is a practical method used for rapid groundwater detection and groundwater salinity assessments and can be executed for reasonable costs. Yet again, its applicability also depends on the geological conditions and measurements are only accurate to a certain depth. Innovative remote sensing technologies such as the NASA GRACE satellite mission are applied to obtain a complementary picture of groundwater storage changes. Proper interpretation of this satellite data requires significant use of proxy information and therefore information is only reliable over larger regions (200,000 km2) .
There is, however, still a lack of groundwater information at regional and global scale hampering assessment and informed water management. Groundwater monitoring networks are crucial for acquisition, collection and assessment of this vital information. Also combining data by harmonization and sharing of information among institutions allows for more complete and reliable groundwater assessments. This applies to groundwater data within a country, but also on the transboundary and global level. In addition, making data available to a broader public generates trust and could allow for more robust negotiations and responsible joint water management, if appropriately utilized.
Setting up information systems improves data management and facilitates groundwater assessments. Recognizing the need for a systematic collection of groundwater data, IGRAC (International Groundwater Resources Assessment Centre) began developing the Global Groundwater Monitoring Network (GGMN) in 2007. Since then IGRAC has been collecting data sets from publicly accessible sources and via participatory processes in the GGMN. Countries that already publish groundwater level data online are connected through automated data flows between these countries’ national databases and the GGMN.
There is an increasing effort to manage data on a global level; the United Nations Global Environment Monitoring System (GEMS) is dedicated to make (ground)water quality data available online, while FAO’s AQUASTAT focuses on providing global (ground)water and agriculture data. Global networks like Group of Earth observations (GEO) and WMO’s Global Climate Observing System (GCOS) and World Hydrological Cycle Observing System (WHYCOS), are initiatives to combine information from different hydrological cycle globally and thereby improve data availability and applicability. Nevertheless, the availability of groundwater data remains limited. Therefore, the expansion of groundwater monitoring and improved access to groundwater data worldwide are key measures to encounter the global water challenges.
i) Margat, J., & van der Gun, J. (2013). Groundwater Around the World. Leiden, Netherlands: CRC Press/Balkema
ii) World Water Assessment Programme (2009) The United Nations World Water Development Report 3: Water in a Changing World. Paris: UNESCO, and London: Earthscan.
iii) Siebert, S., Burke, J., Faures, J.-M., Frenken, K., Hoogeveen, J., Döll, P., & Portmann, F. T. (2010). Groundwater use for irrigation–a global inventory. Hydrology and Earth System Sciences Discussions, 7(3), 3977-4021.