DHI GRAS (DK)
The Sustainable Development Goal (SDG) on water in the 2030 agenda for sustainable development has brought a spotlight to water policy at global level and in national planning and represents a clear indication that countries worldwide recognise the ‘water crisis’, which has consistently been ranked by the World Economic Forum as one of the threats with the highest potential impact and likelihood.
A recent report from the World Resource Institute (WRI) highlights that the ‘water crisis’ is far more commonplace than previously thought. Water withdrawals globally have more than doubled since the 1960s and show 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 depletion. The Sustainable Development Goals, especially the goal on ‘clean water for all’ (SDG 6) and the ‘climate action goal’ (SDG 13) therefore need all the attention they can get to avoid an accelerating ‘water crisis’ towards 2030 and beyond.
A ‘water crisis’ is ultimately a management crisis that can be solved through the application of sound water management policies. 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, for livestock watering and as a source for hydropower and recreation. Still, in most countries, 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 ungauged regions. The unmonitored proportion of water resources represents a major known unknown and representing an information gap 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), and 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 SDG global indicator framework.
The availability of the growing volume of environmental data from the Copernicus Sentinels, combined with data from long-term Earth Observation archives (e.g. Landsat) represents a unique opportunity for the operational usage of EO for operational applications 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 by further developing EO tools and products to effectively use the most up to date, open and free satellite data, primarily from the Sentinel missions, for improved monitoring of the world’s inland water resources in both extent and volume.
WorldWater is about empowering countries and river basin authorities 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.