© Dr. Patrick Wagner

Global Terrestrial Network – Hydrology

GTN-H links existing networks and systems for integrated observations of the global water cycle.

The network was established in 2001 as a „network of networks“ to support a range of climate and water resource objectives, building on existing networks and data centres, and producing value-added products through enhanced communications and shared development.

Observations of the Global Terrestrial Water Resources

Life on earth is closely linked to the availability of water and its variability. However, global change means that the demands placed on water resources are constantly increasing. According to the IPCC conclusion in the 5th Assessment Report, it is likely that human activities have influenced the global water cycle since 1960. Particularly over land, in-situ data provide long-term records of changes in the various components of the hydrological cycle, focusing on the essential climate variables (gcos.wmo.int). In addition, satellite-based remote sensing of water-related parameters is becoming increasingly important to assess changes of the global water cycle.

Global data centres (indicated with their abbreviations in the water cycle figure), often operating under the auspices of UN agencies, collect and harmonise water data worldwide and make the global data sets available to the public again. Most of these relevant Global Data Centres are members of the GTN-H.

The terrestrial water cycle with the global data centres federated within GTN-H

Goals of GTN-H

  • Establish a global hydrological network of networks
  • Plan and implement projects that facilitate access to hydrological networks and observation data as well as generate derived product
  • Form essential components for integrated global and regional hydrological products

Main Objectives

Main objective of GTN-H is to make data from existing global hydrological observation networks available and enhance their value through integration. GTN-H thus underpins the generation of datasets suitable for:

  1. Research in the areas of global and regional climate change
  2. Environmental Monitoring
  3. Hydrology and water resource management

International Context

GTN-H is a joint effort of the World Meteorological Organization / Climate and Water Department (WMO/CLW), the Global Climate Observing System (GCOS), co-sponsored by the World Meterological Organization (WMO), UN Environmental Programme (UNEP), Intergovernmental Oceanographic Commission (UNESCO IOC) and the International Science Council (ISC). It further represents the observational arm of the Group on Earth Observations / Integrated Global Water Cycle Observations Theme (GEO/IGWCO).