A number of organizations both within the United States and throughout the world indicate water availability will be the great challenge of the 21st Century. The water supply needs of a growing population exert increased pressure on the fixed supply of fresh water. Locations in which water was once plentiful are now experiencing shortages. According to the Council of State Governments, water wars in the United States, once limited to the semi-arid Western states, have now spread to the Midwest, East and South of the country. The National Research Council states: “In this century, the United States will be challenged to provide sufficient quantities of high-quality water to its growing population.” The Western Governors Association estimates that economic losses arising from the current drought in the west are “billions of dollars.”

In the United States, annual damages due to floods are $5B, while drought losses average $10B per year. In addition, the Nation’s freshwater supply is critically stressed by a growing population especially in environmentally sensitive areas along the coasts. NOAA’s renewed focus on ecosystem based management is integrally linked to predictive information about the Nation’s freshwater supply. A full suite of water resources information and predictions is required to support this approach. NOAA can lead America to meet 21st century water challenges by engaging partner agencies and the research community to routinely provide water forecasts for economically and ecologically sound watershed management.

Integration of NOAA’s water related activities will be necessary to address the water challenges of the 21st century. Flow forecasts on natural rivers can be used for optimizing the operation of water resources systems, such as reservoir operation for hydropower, flood control, shipping commerce on rivers, potable water supply, irrigation, industrial water supply, thermal power plant cooling, recreation, and fishing. These flow predictions will be used by National Ocean Service estuary models, and must be provided to the National Marine Fisheries Service for species management in the brackish water areas. Better internal NOAA coordination will improve the accuracy and utility of these forecasts. NOAA’s National Weather Service is positioned to lead this activity because of its unique capabilities in data acquisition and processing, existing operational water modeling infrastructure, and robust national service delivery system to provide predictions of water resource variables for forecast periods of hours to months.

The National Weather Service has focused primarily on forecasting floods, although drought outlooks and forecasts in the normal flow ranges are also issued. Property losses and deaths attributable to floods are the largest and second-largest impacts from natural disasters in the United States, respectively. These losses have been steadily decreasing due to the improved lead time and the accuracy of operational forecasts. Water forecast procedures have advanced as a result of intramural and extramural research and development efforts. To address growing water resource challenges, the National Weather Service is putting more emphasis on forecasting the full spectrum of flows ranging from droughts to floods. Seasonal volumetric outlooks, currently produced only at a few River Forecast Centers, are likely to become more widespread. This will require cooperation and coordination within NOAA, as well with other Federal, state, municipal, tribal and private institutions, above and beyond the current levels. Managing water requires observations, data assimilation, and modeling. In the past, NOAA focused on precipitation information and flood forecasts, which relied on river and reservoir stage observations from the U.S. Geological Survey (USGS). Because water diversions during flooding are either minimal or irrelevant when compared to the total volume of a river flow, coordination with other agencies has involved those that operate reservoirs, such as the Bureau of Reclamation and the U.S. Army Corps of Engineers (USACE). River flows in the normal ranges down to drought levels are greatly affected by water diversions for supply, irrigation, thermal power plant cooling, and returns from agricultural uses. Groundwater levels, soil moisture, and river flow observations must be assimilated into flow forecasting models to increase their accuracy. The cooperation between the USGS and NOAA that has been going on for decades will be strengthened. Other Federal agencies which NOAA routinely cooperates with in the water area are the Department of Agriculture’s Natural Resources Conservation Service (NRCS), Environment Protection Agency (EPA), U.S. Forest Service, Department of Defense, National Aeronautics and Space Administration, and Department of Homeland Security. This cooperation extends to state, regional, municipal and tribal water agencies, and some private utilities and water managers.

America’s water resource managers require dramatically more predictive information than NOAA currently delivers. Freshwater forecasts must be produced in high resolution gridded format. Additional forecasts of water resource variables such as soil temperature, soil moisture, and evaporation are needed. While some of the scientific breakthroughs to produce water resources information have occurred, complex additional multidisciplinary research is necessary. Collaborative research both within NOAA and outside NOAA (academia, other governmental agencies, private industry) will be critical to achieving these goals. Concurrent, advances in data assimilation and hydrologic science are necessary to produce the type and quantity of information requested by NOAA’s water resource customers. High-resolution, integrated analyses of in-situ and remotely sensed environmental information will be assimilated for use by fresh and salt water forecasting systems. Data from the National Integrated Drought Information System and the Modernized Cooperative Observer Network will be key components of the water resources data assimilation effort. An equally important factor in reaching this goal is the availability and accessibility of observed data for as many forecast variables as possible. NOAA’s water resources program will fully leverage existing USGS, NRCS, and EPA surface and ground water monitoring networks, and justify the expansion of these networks. A Community Hydrologic Prediction System for watershed management will be delivered to support the operational implementation of advanced water quantity and quality models not currently available at NOAA. The open architecture of this new system will facilitate collaboration with the USACE, EPA and USGS to enable NOAA to predict changes in freshwater resources and the environment caused by floods, droughts, sediment and pollutant transport, evapotranspiration, soil moisture storage, and runoff processes.