Fresh water is vital for life. On average, a human being cannot survive more than three days without water. Water is also essential for the production of virtually all of our goods and services. It is the most important and widely used source of renewable energy – hydropower represents approximately 16% of total electricity production worldwide. 

Fresh water resources are diminishing and deteriorating under demographic and climatic pressures.  Decision-makers responsible for the sustainable development of freshwater resources need access to accurate and reliable water-related data. WMO supports an integrated, multidisciplinary approach to managing water resources.

WMO promotes water resource assessments by National Hydrological Services who, in turn, provide the forecasts needed to plan water storage for domestic requirements, agricultural activities, hydroelectric power generation and urban development. 

The WMO World Hydrological Cycle Observing System (WHYCOS) assists National Hydrological Services in establishing and maintaining systems for acquiring and disseminating accurate and timely water-related information essential for formulating integrated water resources management strategies. Equipped with better hydrologic information, assessments and forecasts, Members are able to independently assess their water resources and respond to the threat of floods and drought.

The Hydrology and Water Resources Programme (HWRP) promotes water-resource assessments and supports National Hydrological Services, River Basin Authorities and other institutions responsible for water management in a wide range of activities. Its aims is to improve effective use of hydrology in sustainable development to reduce the risk and impacts of water-related disasters, such as floods or droughts, and to support effective environmental management at all levels. The Quality Management Framework – Hydrology provides strategy, advice, guidance and tools for National Hydrological Services to attain quality, efficiency and effectiveness in their functioning.


In many parts of the world, flooding is a major problem. In the period from 1970 to 2012, storms and floods caused over one million deaths. Flood plains are often attractive areas for human development and a vast share of the world’s population depends, whether directly or indirectly, on a number of key natural resources that are generally provided by floodplains. 


Drought is a prolonged dry period in the natural climate cylce that can occur anywhere in the world. It is a slow on-set phenomenon caused by a lack of rainfall. Compounding factors, such as poverty and inappropriate land use, increase vulnerability to drought. When drought cases water and food shortages, there can be many impacts on the health of the population, which may increase morbidity and result in death.

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The World Hydrological Cycle Observing System

The World Hydrological Cycle Observing System (WHYCOS) is a framework programme of the World Meteorological Organization dedicated to improving basic observation activities, strengthening international cooperation and promoting the free exchange of data in the field of hydrology.

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