HydroSOS – The Hydrological Status and Outlook System

 – Towards providing information for better water management

Water-related hazards and threats are a source of deepening concern globally. Tens of millions of people worldwide are affected by these events, and damages are estimated to cost in the order of magnitude of billions of US dollars per year1. Water hazards are consistently identified as among the highest global risks in terms of impact (World Economic Forum (WEF), 2020). And scientists expect water-associated risks to intensify in the coming years due to climate change, population growth and increasing economic activities.

Some of the principal water challenges include: securing water supplies; designing appropriate water governance schematics; sustaining the management of transboundary basins; managing flood and/or drought; and ensuring ecosystem- protection and conservation. One of the main difficulties in trying to effectively manage water resources and address such challenges is the lack of hydrological information products targeted to serve the needs of different sectors. This information deficiency is often driven by three factors:

  • insufficient local-scale data
  • a lack of regional to global coherence in hydrological information and modelling systems
  • limited dialogue between the multitude of actors, which renders the understanding of stakeholders’ water management needs unclear.

Because of these shortfalls, water managers and stakeholders cannot properly assess the availability of water resources on different spatio-temporal scales. They also cannot foresee how the availability of water might change over the near future, thus rendering water management and planning difficult, if not impossible. A framework is needed that can bring regional and global monitoring data together with locally collected data, analyses and basin-scale modelling systems. The WMO Global Hydrological Status and Outlook System (HydroSOS) is that mechanism. HydroSOS aims to fill in the shortfalls in order to facilitate the tasks of water managers and stakeholders in the face of intensifying water threats and risks. 


Addressing Water Challenges through HydroSOS

HydroSOS Elements

A global framework for the production and sharing of water-related information products could produce a unified assessment and prediction system. This, in turn, could help us understand the current status of surface and groundwater hydrological systems as well as predict their evolution over the coming weeks to months. The main objective of HydroSOS is to develop such a system by bringing National Meteorological and Hydrological Services (NMHS) together to improve the provision of reliable, timely, accurate and relevant hydrological status assessments and outlook products to inform water resources management.

Such products need to be derived from systematically collected, comparable and trustworthy local-scale data. This information needs to be consistent with national, regional and global information. HydroSOS will thus permit NMHSs to respond to pressing questions from decision-makers, such as: “How much water is there available in my basin/region at the moment?”; "Is the current situation normal?"; and "How might the local and regional flood/drought situation change in the coming weeks to months?”

HydroSOS will support national capabilities to assess current hydrological status- and forecast-outlooks, as some WMO Members still do not have the tools and skills to undertake such analysis. Moreover, it will provide consistent hydrological status and outlook information, which is not often available at present across transboundary basins or regions of shared hydrological interest. Finally, it will bridge the information gap between locally-informed hydrological and information products and those developed globally.


HydroSOS within WMO

In December 2016, the WMO Commission for Hydrology initiated HydroSOS and approved the formation of an Expert Task Team to oversee the pilot phase of this initiative. In June 2019, the Eighteenth World Meteorological Congress recognized the HydroSOS initiative as a fundamental component of the WMO Strategic Plan (Resolution 25, Cg-18). HydroSOS will support eight of the long-term ambitions for an operational hydrological community (Resolution 24). It will directly address Long-term Ambition Six, which states: “We have thorough knowledge of the water resources of our world” (for more information see WMO Long-Term Ambitions for the Operational Hydrological Community). It will do this by enabling a monitoring system that produces information that can be used to optimize existing services as well as future policies and services and decision-making from the local to the global scale.

HydroSOS supports the full value-chain for services by focusing on the development and sharing of inter-operable hydrological status and outlook information products and by drawing upon existing WMO initiatives. First, it will enhance hydrological monitoring and data exchange such as the Global Hydrometric Support Facility (HydroHub), through three of its components: the World Hydrological Cycle Observing System (WHYCOS), the WMO Hydrological Observing System (WHOS), and the World Water Data Initiative (WWDI). Secondly, it will advance hydrological forecasting, water resources assessment and early warning capabilities such as the Flood Forecasting Initiative (FFI), the Flash Flood Guidance System (FFGS), and the Dynamic Water Assessment Tool (DWAT). 


National Hydrological Services at the centre of HydroSOS

The WMO HydroSOS will be designed for, and operated by, National Hydrological Services (NHSs). It will enable them to better support a range of stakeholders – including government bodies, different socioeconomic sectors such as energy and agriculture, regional and international aid agencies, and the public – in decision-making related to water management.

HydroSOS will build capacity to undertake hydrological status assessments and develop outlooks within NHSs; it will directly draw upon existing and planned WMO initiatives in relation to hydrological monitoring, data sharing and sub-seasonal to seasonal hydrological and meteorological forecasting, together with different partners.


The working structure of HydroSOS

A set of work packages – addressing coordination, standardization of technical approaches, implementation and delivery – have already been established for the pilot phase of HydroSOS.

Work Package 1 (WP1), coordination, focuses on programme management, communications and resource mobilization. Furthermore, it considers linkages with other WMO initiatives such as WHOS, WHYCOS, WWDI, and the Global Data-Processing and Forecasting System (GDPFS).

Work Packages 2a, 2b and 2c focus on the standardization of technical approaches and aim to develop the technical protocols needed for HydroSOS. Furthermore, WP2 compares the different methodologies that could be recommended to NMHSs (and others) that do not currently have well-developed hydrological status assessment and outlook capabilities but want to provide information services.

In 2019, WP2a performed a review of the climate, hydrology and terrain data available at the global, regional and country levels. While WP2b compiled a series of hydrological status assessment methodologies from around the world, including consideration of the definition of “normal” hydrological conditions for both streamflow and groundwater. Whereas WP2c made important advances in evaluating the technical performance of sub-seasonal to seasonal hydrological forecast methods. Thus, WP2c resulted in a greater understanding of the strengths and weaknesses of different outlook-generation methods on local and global scales – and of the causes of the contrasting performances among them.

Implementation of WP3 and WP4 is now ongoing at regional and global levels. WP3a and 3b are implementing two Regional Capacity Development pilots: one in the Lake Victoria Basin, the other in South Asia (Ganges-Brahmaputra-Meghna Basin). The two proof-of-concept pilots aim to assess how shared HydroSOS capabilities can be developed in transboundary basins or regions of shared hydrological interest. The assessments of regional needs and capabilities were already carried out in the two pilot basins in 2019 through in-depth discussions with NMHSs and other stakeholders.

In the meantime, WP4 is assessing the role of large-scale (global/continental) status and outlook products in supporting and supplementing local-scale (basin/national/regional) products. NMHSs often have difficulty reconciling local information with the large-scale products of global modelling centres and research organizations. WP4 aims to assess such products, analyse their possible use in HydroSOS and determine how new WMO products can be developed specifically to support NMHSs locally. So far, work has focused on comparing global hydrological models to see if any of them can be used for specific basins – and under what conditions one product might perform better than the others.

Delivery, the final stage of the pilot project, includes two work packages. WP5 covers Product Communication and Dissemination, while WP6 deals with Capacity Development and Training. An early-stage prototype, HydroSOS Global Portal, is being developed as part of the delivery stage to show how hydrological status and outlook products from around the world could be brought together. In November 2019, the Nanjing Hydraulic Research Institute (NHRI) hosted the first HydroSOS Technical Workshop in Nanjing, China. The Workshop took stock of progress-to-date and determined the steps needed in order to present the pilot phase findings to the Extraordinary Session of the World Meteorological Congress in 2021.


The South Asia (Ganges-Brahmaputra-Meghna Basin) Pilot

WP3a conducted national HydroSOS capacities and needs assessments in four of the countries along the Ganges-Brahmaputra-Meghna basin: Bangladesh, Bhutan, India and Nepal. The focus was on the national institutional capacities of NMHSs, the availability of hydrometeorological data, mapping stakeholder needs and the challenges to implementation of HydroSOS.

All four countries had good networks of hydrometeorological data and easily-accessible digitally-formatted historical data. Their real-time hydrometeorological data networks are being expanded and will be adequate for HydroSOS. However, the sharing of river discharge data between some countries is limited and some NMHSs in the basin are bound in the activities by low staff, budget and technological capacity.

There is a significant need for a regional HydroSOS in the basin, especially for agriculture, energy and navigation. Demand for water resources is growing in the basin, which currently has one million hectares of irrigated land, one hundred thousand Megawatts (MW) of hydro-electric capacity and an extensive criss-cross of river navigation. In addition, the basin suffers from frequent floods, landslides and droughts.

Improvements in the management of water resources – which will better the livelihood of about 750 million people and increase the economic development of the region – will be underpinned by HydroSOS. Many sectors will benefit from HydroSOS, including hydropower operators, water supply management, river navigation operators and disaster management agencies. Most notably, agricultural output would increase with improved management of groundwater, irrigation water and drought risks.


The Lake Victoria Basin Pilot

In 2019, WP3b assessed HydroSOS capacities and needs assessments in five countries of the Lake Victoria Basin: Burundi, Kenya, Rwanda, Tanzania and Uganda. Its goal was to gain a thorough understanding of the operations and capacities of NMHSs and regional institutions and to identify needs and opportunities for taking HydroSOS forward. Consultations were carried out with NHSs; National Meteorological Services (NMSs); selected national institutions responsible for disaster management and hydropower management; and regional institutions responsible for water, climate and governance.

Data collection infrastructure for both meteorology and hydrology exists in all the countries. However, the potential use of data for real-time water resources management is not realized in all of them – except to some extent in Rwanda – because of a lack of operational telemetry and insufficient data processing and management systems. Staffing levels and financial constraints do not permit any to operate and maintain a complete national network of stations. Many NHSs and NMSs around the world face similar problems; WMO efforts under the HydroHub will focus on addressing them.

Despite the observation network issues, the WP3b assessment concluded that significant steps forward can be made through HydroSOS. If needed resources are provided to the region to develop and deliver status and outlook products, there can be significant benefits for all stakeholders: delivery of such products would finally bring real value from the many projects, past and present, that have supplied instrumentation and capacity building to stakeholders in the region to generate usable data and information.

The beneficiaries of both status and outlook products in the Basin include the hydropower sector, agricultural producers and those operating irrigation systems – whose work would benefit especially from rainfall, soil moisture, and temperature outlooks. These products are also essential for public health managers and those controlling reservoir storage and groundwater pumping for domestic, agricultural and industrial water supplies. The WP3b assessment also indicates that most of the users of status products are interested in short-term weekly and monthly outlooks – thus, the region has a large and receptive number of users of hydrological outlook products.


Path forward

HydroSOS is still in its pilot phase. Work continues on the analysis of the methodologies to define hydrological status and create local, basin-scale hydrological outlooks that can be integrated across regions and the globe. This will help to define the initial technical protocols and standards on which HydroSOS will be based.

Implementation plans to extend the WP3a and WP3b pilots to other regions are currently being drafted. The plans will include technical protocols and standards and stakeholder workshops to better understand user needs. It will aim to enhance cooperation between participating NMHSs and regional organizations in order to produce more meaningful hydrological products for the populations living in the two basins.

Work is also ongoing to determine how global hydrological models perform in comparison to regional/local models and on how a regionally-informed global system might be built.

HydroSOS is on course to develop a demonstrator portal, where hydrological data from different countries, including the pilot countries, is being incorporated into a web interface of hydrological indicators. This portal will be tested and perfected to better understand how the delivery mechanism of HydroSOS will work.

Once the pilot phase has produced more substantive results, WP6 on capacity development will begin to define and create the materials required for a successful transfer of technology and know-how to participating countries. WP6 will ensure that hydrological products are created to the highest standards possible.


Who we are

The HydroSOS global team is comprised of a multidisciplinary and multi-cultural group of experts from NMHSs, academia and research institutions. Many international and regional organizations have donated in-kind to HydroSOS with their expertise and time. At present, HydroSOS experts represent five NMHS, four NMS and eight NHS from fifteen countries, nine research/scientific institutions in seven countries, three regional organizations in Africa, and four international organizations. Furthermore, the community of WMO Regional Hydrological Advisers have provided inputs to the initiative since its inception.

The current Work Package leaders are:

  • WP1 - Coordination: United Kingdom Centre for Ecology and Hydrology (UKCEH)
  • WP2a-Data Sources and Exchange Methods- Nanjing Hydraulic Research Institute (NHRI)
  • WP2b - Current Status Assessment and Modelling Methods: United States Geological Survey (USGS)
  • WP2c - Hydrological Forecasting and Modelling Methods: Australia’s Bureau of Meteorology (BoM)
  • WP3a - South Asia Pilot: Independent consultant from Nepal
  • WP3b - Lake Victoria Pilot: Uganda’s Ministry of Water and Environment (MWE)
  • WP4 - Global Pilot: UKCEH
  • WP5 - Product communication and dissemination: United States National Center for Atmospheric Research (NCAR)
  • WP6 - Capacity Development and Training: Currently vacant


Get involved

As HydroSOS pilot phase moves to implementation, enhanced skills are sought for the project. For example, groundwater and soil moisture experts are needed to help the team to better understand these processes and properly include them in the development of the system. Additionally, the meteorological community is encouraged to help establish links between sub-seasonal and seasonal meteorological forecasts. Also, experts in capacity development in the hydrology domain are sought to help HydroSOS to develop comprehensive materials for NMHSs such as guidelines and training manuals.

HydroSOS is looking specifically for methodology cases from NMHSs about how they generate and use hydrological status and outlooks. Moreover, HydroSOS seeks to develop greater links within the WMO Regional Associations by engaging with regional working groups on hydrology.

HydroSOS aims to bring operational and research hydrologists and meteorologists together at national, regional and global levels. By engaging with HydroSOS, the research and global modelling communities will be able to co-design and refine products with the WMO network of NHS, increasing their utility to operational water managers and the contribution they make to future water security.

WMO and the HydroSOS team are looking forward to engaging with more Members and their experts in developing a framework for the System. HydroSOS is looking for contributions, both in-kind and financial, for the implementation of its pilot phase.



1 The United Nations World Water Development Report 2019: Leaving No One Behind. Paris, UNESCO World Water Development Report 2019: Leaving No One Behind. Paris, UNESCO



Alan Jenkins, UK Centre for Ecology and Hydrology

Harry Dixon, UK Centre for Ecology and Hydrology

Victoria Barlow, UK Centre for Ecology and Hydrology

Katie Smith, UK Centre for Ecology and Hydrology

Johannes Cullmann, WMO Secretariat

Dominique Berod, WMO Secretariat

Hwirin Kim, WMO Secretariat

Michael Schwab, WMO Secretariat

Luis Roberto Silva Vara, WMO Secretariat



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