An improved description of the global water cycle, especially the continental branch, is of major importance for inventory and eventually better control of water resources available for human consumption and activities (agriculture, urbanisation, hydroelectric energy resources), as well as for climate prediction.
In this context, the second 'Space for Hydrology' workshop, organised by ESA in collaboration with the World Meteorological Organization (WMO), was held in Geneva, from 12-14 November 2007.
The workshop assessed the current stage of knowledge and activities in space-based hydrological observations and to exchange knowledge and know how with hydrologists and researchers.
Continental waters have a crucial impact on terrestrial life and human needs, and play a major role in climate variability. Without taking into account the ice caps, fresh continental waters are stored in various reservoirs: the snow pack, underground reservoirs, the root zone (first few meters of the soil) and vegetation, and as surface waters (rivers, lakes, man-made reservoirs, wetlands and inundated areas). Water on Earth is continuously recycled through precipitation, evapotranspiration, runoff, and vertical and horizontal diffusion and transfer in soils.
Remote sensing techniques can now be used to monitor water balance of large river basins on time scales ranging from weeks to months: among these, the most promising are satellite altimetry on surface waters (rivers and their tributaries, wetlands and floodplains) providing water levels and space gravity missions providing estimates of spatio-temporal variations of terrestrial water storage in soils (soil wetness and groundwater) and in surface water reservoirs. To be used in conjunction with in situ observations and hydrological modeling, these observations from space have the potential to significantly improve our understanding of hydrological processes affecting large river basins in response to climate variability.
The objective of this workshop was to bring together hydrologists, both developing models and collecting in-situ data, from 'global scale' to 'regional scale', and space scientists in order to develop further scientific interactions between these communities and develop new demand-driven products, tailored to hydrological requirements.
- Global hydrological modelling: objectives, state of the art, improvement and requirements, contribution of space observations.
- From Large-scale hydrology to Small-scale hydrology: Do hydrology requirements depend on scale? How space techniques can answer these challenges?
- Monitoring Spatio-temporal changes of surface waters: applications to climate research and water resources management and contribution of space observations.
- Space techniques to measure hydrological variables
- Global land hydrology and its geodynamic effects
- Radar altimetry processing for inland water levels
- SAR for DEM and water surface characterization
- Accuracy and space-time resolution needed for global and regional hydrological model parameters
- Rain, snow and ice cover in river watershed and its role in the formation of river discharge
- Steps towards estimation of river discharge from space
- Other applications of space observations in large river basins (e.g., sediments transport, systematic mapping of wet areas, flood monitoring, use of altimetry for vertical referencing, etc.)
- Data assimilation of space observations applied to hydraulic parameter identification. Expected potential of space data in hydrologic and hydrodynamic modeling.
- Strategic combinations of satellite and ground-based data for large scale hydrological monitoring: improvement expected.
- Round table discussion: Current and future challenges in hydrology: What are they and how to face them? How to strengthen the collaboration between the two communities: hydrologists and space observation scientists? Synthesis and recommendations: action plan, future workshops.