• hydrology;
  • tectonics;
  • water cycle;
  • hydrogeodesy

[1] IGCP 565 Workshop 3: Separating Hydrological and Tectonic Signals in Geodetic Observations; Reno, Nevada, 11–13 October 2010; The third International Geoscience Programme (IGCP) 565 workshop took place in Nevada. There were 57 participants from 11 countries representing universities, national laboratories, and government agencies. A series of plenary presentations was followed by breakout sessions addressing topics that included the advances needed to improve modeling algorithms for applications of geodesy to hydrology, working with the Group on Earth Observations (GEO) Water Cycle Community of Practice, and developing a hydrogeodetic data portal. The presentations and discussions underlined the added value in applying geodesy to support hydrologic cycle monitoring and modeling, especially terrestrial water storage. However, before the full benefits of the emerging field of hydrogeodesy become exploitable, there is a need to reduce model uncertainty through validation with point to basin observations; to increase consistency in processing and modeling displacement, gravity variations, and hydrologic processes; and to develop new technologies that merge scale mismatches. Improving accuracy and stability of the geodetic reference frames will extend the applicability of geodesy to hydrologic problems. In tectonically active areas, joint interpretation of tectonic and hydrologic signals is required. Ground truth networks are needed at a higher density and with quality control protocols that ensure accuracy.