The IGCP 565 Project

Significance

The IGCP 565 Project provides a frame for research, development, and capacity building with scientific, technological, and societal relevance:

• A) Scientific significance: The global water cycle operates in a continuum of temporal and spatial scales and exchanges large amounts of energy as water undergoes phase changes and is moved from one part of the Earth system to another. Its variability, which regulates flood, drought, and disease hazards, continuously is being transformed by climate change, erosion, pollution, salinization, agriculture, and civil engineering practices. The most visible impact expected from climate warming include changes in the distribution of precipitation and evaporation, and the exacerbation of extreme hydrological events, floods, and droughts. Understanding the water cycle, quantifying the mass redistribution, and developing predictive capabilities are therefore mandatory prerequisites for understanding global change processes. Despite the importance of the global water cycle for understanding the Earth as a planetary system, and despite the crucial role of water for the welfare of human societies, our knowledge of the mass transport in the global water cycle and the variations in the various reservoirs of this cycle is still limited by large quantitative uncertainties particularly at subseasonal to interannual time scales and regional to global spatial scales.

  Although GRACE has provided the best estimates of changes in water storage on land and in ice sheets on sub-continental scales, and GPS observations have provided quantitative estimates of the seasonal changes in hemispheric water storage, the current water mass changes derived from space-geodetic observations are hampered by a number of short-comings (see the summary of science issues). The IGCP 565 Project addresses these short-comings and is expected to significantly improve the accuracy, spatial resolution and temporal coverage of water mass changes determined from space-geodetic observations. The anticipated dynamic reference Earth model for surface loads will provide better insight in the fluxes between the various reservoirs of the water cycle. Validation based on and assimilation of the space-geodetic observations in water cycle models is expected to reduce inter-model differences and to improve the predictive capabilities of these models.

• B) Technological advances: Improved models of surface mass changes and their fingerprint in the geodetic observations will provide a basis for the development of products that support regional water management. In this way, the full suite of space-geodetic observations will be made available for practical applications.
• C) International cooperation: GGOS is based on the best effort of institutions of many countries (of the order of 100). However, active representation of institutions from developing countries is limited and the project aims to increase integration of these institutions into GGOS with particular focus on the activities related to the monitoring of the global water cycle. The IGCP 565 Project provides a formal frame for improved international cooperation of the GEO and GGOS activities aiming at improved monitoring of the global water cycle. It also fosters links between ongoing water-cycle releated international programs and the relevant GEO Tasks.
• D) Knowledge transfer: The IGCP 565 Project has a strong focus on knowledge transfer to developing countries in several areas. The anticipated participation of one or more emerging space agencies in Africa and/or Asia in a follow-on GRACE-like mission will lead to significant technology transfer to these agencies. Integration of institutions in developing countries in data processing and interpretation, particularly in the frame of GGOS, will lead to knowledge transfer to these institutions and support capacity building with respect to research. Developing products for applications in developing countries will facility capacity building in the utilization of Earth observation products for societal applications. With these goals, the project is fully aligned with the goals of GEO with respect to data sharing, knowledge and technology transfer in Earth observation, and capacity building in applications utilizing Earth observation products.
• E) Societal impact: Water is essential to life on Earth, which is a unique, living planet due to the abundance and vigorous cycling of water throughout the global water cycle. Water is central to human welfare, progress and sustainable economic growth. Clean, fresh water is arguably the most important resource to human society, as it controls our ability to produce sufficient food to support the burgeoning human population. Usable water resources reside in lakes, streams, artificial (dammed) reservoirs, and groundwater. Of these, ground water represent the greatest volume, and is also the most vulnerable to long-term contamination. The level of highly variable internally draining lakes must be consistently monitored in order to track changes in available irrigation water as a result of surface water diversion (commonly for irrigation). Further salinization of surface waters, rendering them useless for irrigation and other uses should be monitored so that water use policy upstream can be more effectively developed. The discharge of rivers into the global ocean controls coastal zone water chemistry and ecosystem function, yet is highly modulated by water use throughout the drainage basin.

  The vast majority of liquid fresh water on the planet resides underground, and is easily accessible through wells. However, in semiarid to arid regions, where the stress on water resources is most acute, aquifers do not recharge at a significant rate relative to rate of withdrawal. Utilization of such water resources is considered “mining” as this water is a non-renewable resource. Consequently, water tables drop, and the aquifers are assigned limited lifetimes before depletion. Knowledge of the changing mass distribution due to water withdrawal and/or changes in precipitation, evaporation, and runoff is therefore a fundamental input to any responsible water management. However, in situ observations are limited, particularly in many developing countries.

  In many areas of the world, current demands exceed the supply (as indicated by the water scarcity index, see Oki & Kanae, 2006), and water has to be transported over great distances. This situation is expected to become more severe over the next several decades (see, e.g., EEA, 1999; Lawford et al., 2004; Bernasconi et al., 2005; Oki & Kanae, 2006; United Nations, 2006). However, the water crisis is largely a crisis of governance (United Nations, 2006), brought about by water management obstacles such as sector fragmentation, poverty, corruption, stagnated budgets, declining levels of development assistance and investment in the water sector, inadequate institutions and limited stakeholder participation. The lack of detailed knowledge of the global water cycle from local to global scales is contributing and enforcing this crisis. Therefore, Earth observations can improve the knowledge base and thus help to mitigate this crisis. As discussed above, on regional to global scales, the mass transports observed by GGOS are already improving the database concerning the motion of water through the hydrological cycle, and future combined analysis of the variations in Earth's gravity field, shape and rotation will help to reduce the uncertainties.

  The societal significance of the IGCP 565 Project is also underlined by the fact that the Earth Observation Summits (EOS) identified “Improving water resource management through better understanding of the water cycle” as one of the nine Societal Benefit Areas (SBAs) of Earth Observations (see Appendix 4 in GEO, 2005). Subsequently, the GEO members have initiated several water-related tasks in the GEO Work Plan 2007-2009, and the Task WA-07-02 specifically addresses the quantitative monitoring of the global water cycle based on satellites and remote sensing. The IGCP 565 Project directly contributes to this GEO Task.