The Full background

The dedicated water goals in the 2030 agenda for sustainable development have brought water policy into the spotlight, both at a global level and within national planning. This represents a clear indication that countries worldwide recognise the threat of a ‘water crisis’, consistently ranked by the World Economic Forum as one of the most likely and most devastating threats to our planet. A recent report from the World Resource Institute (WRI) documents that the ‘water crisis’ is already real and far more commonplace than previously thought. WRI found that water withdrawals globally have more than doubled since the 1960s due to growing demand, showing no signs of slowing down. Population growth, socioeconomic development and urbanization are all contributing to increased water demand, while climate change induced impacts on precipitation patterns and temperature extremes further exacerbate water resource availability and predictability. The Sustainable Development Goals (SDGs), especially the goal on ‘clean water for all’ (SDG 6) and the ‘climate action goal’ (SDG 13) therefore need urgent attention to avoid an inevitably accelerating ‘water crisis’ as we head towards 2030.

A ‘water crisis’ is ultimately a management crisis that can be solved through the application of sound water management policies and initiatives. The need for proper and timely information on water (non-) availability is probably the most important requirement for water management activities. In large, remote and inaccessible regions, in-situ monitoring of inland waters is sparse and hydrologic monitoring can benefit from information extracted from satellite earth observation (EO).

Rivers, streams and lakes/reservoirs throughout the world provide water for domestic usage as well as for irrigation, livestock watering and as a source of hydropower and recreation. Still, in most countries, the government’s measurement of water resources is limited to major dam resources and river flow stations. This however represents only a small portion of the overall water resources, with substantial portions of water being stored in privately held infrastructure such as farm dams. The vast unmonitored proportion of water resources represents a major “known” unknown, which can produce inaccuracies that may lead to ineffective or erroneous decision-making.

Monitoring water bodies for a whole country or river basin in a comprehensive manner is essential for the national water resources management in respect to drought mitigation, irrigation management and planning of infrastructure investment (e.g. dam constructions). EO is increasingly being recognized as an essential tool for large-scale monitoring of water resources. This is needed to promote more efficient planning and decision making, as well as for direct reporting in response to the global indicator framework for the SDGs.

The availability of the growing volume of environmental data from the Sentinels, combined with data from long-term Earth Observation archives (e.g. Envisat and Landsat) represents a unique opportunity for the operational usage of EO in support of water resource management.

Global EO based surface water maps are already readily accessible (cf. JRC Global Surface Water Explorer, Deltares AcquaMonitor and GLAD Global Surface Water Dynamics), but the global products are based solely on optical data (cf. Landsat) and will inevitably tend to have a bias at the national/local level. By launching the WorldWater project, ESA is aiming to meet these shortcomings and fill an important gap by bringing the necessary EO data and tools, capacity building and guidelines to users in need of better information on surface water dynamics.

WorldWater is about empowering users so they can independently monitor surface water dynamics at all scales in a robust way – thereby providing them with essential information for more evidence-based planning and management of water resources and an ability to efficiently report and act in response to the global water agenda.