National Aeronautics and Space Administration

Water Management

Photo: In the Boulder Basin of Lake Mead, the lower water level has connected former islands like Saddle Island to the shoreline. The National Park Service has also moved marinas to the new shoreline or new sites, such as moving Las Vegas Bay marina to Hemenway Harbor. (Image by Jesse Allen, based on data provided by the Landsat 7 Science Team)

Viewed from above, our home planet stands out--a "blue marble" set against the vast blackness of outer space, with an abundance of water on its surface. Yet, only a small amount of this water is fresh and suitable for consumption by plants, animals and humans. Monitoring the surface and ground water supply is a vital societal need. Surface water includes both flowing water in streams and rivers, and impounded water in natural lakes, polar ice caps, and human-made reservoirs. Ground water includes the large amounts of water stored beneath the Earth's surface in aquifers--vitally important to the viability of agriculture in drier climates. It is important to determine where supplies of fresh water are located, to quantify how much water is available, and to figure out how fast the water supply is increasing or decreasing. Increased demand threatens to deplete these precious water resources and accurate information on water availability (e.g., from surface reservoirs, snowpack, underground aquifers, etc.) is needed in order to meet the water resource needs of an ever-growing population.

Not only must society concern itself with having water in sufficient quantity, but it also needs to ensure the quality of the available water. Potable water quality issues impact every region of the country and while pollution from point sources has been identified and is relatively well characterized, non-point-source pollution is a much more difficult problem. There are also issues of intermittent flow, and the relation to the variability in stream flow rates that are still not well understood. In addition, underground aquifers must be better characterized in terms of their location, recharge rate, and the potential for having contaminated surface water leech into these underground water reserves. Improvements in water quality monitoring are needed and can benefit from NASA Earth science information.

Photo: Data from TRMM and other satellites estimated more than 16 inches of rain fell in the red areas of the top map (TN, AL, GA) from May 4-9, 2003 from spring storms. Credit: Hal Pierce/Jeff Halverson, NASA Goddard Space Flight Center.

The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth's Radiant Energy System (CERES) instruments on the Terra and Aqua spacecraft are helping to refine our estimates of surface energy balance at the surface, which helps to improve our understanding of evaporation over the Earth's surface. The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on Aqua is refining our ability to track changes in surface soil moisture and to represent these processes in atmospheric models. The Tropical Rainfall Measuring Mission (TRMM) monitors tropical/subtropical precipitation patterns. Gravity Recovery And Climate Experiment (GRACE) will allow us to track changes in water storage beneath the surface layer and should help us track water storage changes over the continents. Supplemented by other information, this should allow us to monitor aquifer water storage changes from space. The Global Precipitation Measurement (GPM) mission, a successor to TRMM, and National Polar-orbiting Operational Environmental Satellite System (NPOESS)--missions planned for later this decade--will lead to steady improvements in water quantity assessments.

Landsat 7 and the Hyperion instrument on Earth Observing-1 (EO-1) obtain visual images of sections of the Earth that can be analyzed to track changes in water quality over time. The Landsat Data Continuity Mission (LDCM), a joint NASA/U.S. Geological Survey (USGS) mission, will continue the long-running Landsat data record, and enhance our capabilities to remotely sense water quality in the coming years.

Incorporating all of this information into decision support systems will lead to improved capability to predict water availability, protect water quality, and plan for water conservation. Many agencies, including the U.S. Department of Interior's Bureau of Reclamation (BoR), the Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA), will benefit from these improvements to decision tools used for water management.