World Meteorological Organization

The goal of observations of the hydrological cycle is to collect reliable data for use in water resources planning and decision-making, including for managing flood and drought conditions, integration into hydrological and climate applications and services, and for research. Decisions may be made from raw data measurements, based on derived statistics, or on the results of many stages of modelling beyond the raw data stage, but it is the collected data that form the basis for these decisions. Hydrological datasets have intrinsic value and are worth the huge human and financial commitment required to collect them over long periods of time. Their intrinsic value is revealed when the data are open, discoverable, accessible and interoperable, allowing various end-users to use and reuse them. It is essential that the management and sharing of hydrological data is performed effectively to maximize the benefits of data collection and optimize data reuse, and thus get a return on investment in data collection.

In early 2013, the president of the now superseded WMO Commission for Hydrology (CHy) proposed the development of a WMO Hydrological Observing System (WHOS) as the hydrological component of WMO Integrated Global Observing System (WIGOS). In September 2014, the CHy Advisory Working Group endorsed the concept and development of WHOS.

In 2015, the World Meteorological Congress urged the promotion of WHOS among National Hydrological Services (NHSs) and the hydrological community. Congress advocated for a full implementation of WHOS.

The implementation of WHOS is being carried out in two phases:

• WHOS Phase I provides a map interface with links to those NHSs that make their real-time and/or historical hydrological data available online.
• WHOS Phase II provides a fully WMO Information System (WIS)-compliant services-oriented framework linking hydrologic data providers and users through a hydrologic information system of systems enabling data registration, discovery and access.