Hydrological Services (HSs) are national public agencies mandated to provide basic hydrological information and warning services to the government, the public, and the private sector in support of protecting lives and livelihoods. HSs aim to fulfill the state and public need for robust water monitoring, data management, and prediction, providing authoritative and actionable information on hydrometeorological trends and extremes. HSs also deliver socioeconomic benefits through improved water resources and disaster risk management, with benefit–cost ratios frequently on the order of 3–4 and higher.

The World Bank Group (WBG) and the World Meteorological  Organization (WMO) have become increasingly concerned that, particularly in low- and middle-income countries, HSs are unable to respond to the growing demand for easily accessible, robust, and timely information. As such, the WBG Water Partnership Program, the WMO, and GFDRR assessed  Hydrological Services in such countries to better understand their status, performance obstacles, and investment needs.