Tracking Fresh Water from Space Seed funding from the Terrestrial Hydrology Program at NASA: Jared Entin, Program Manager Doug Alsdorf, U.S. WaTER PI Nelly Mognard, EU WatER PI WatER is an international satellite mission to meet the requests of the President’s OSTP & OMB directive to “measure, monitor, and forecast the U.S. and global supplies of fresh water” and to meet the U.N.’s resolution “that the goals of the Decade should be a greater focus on water related issues at all levels and on the implementation of water-related programmes and projects…” WatER initiated from NASA’s Surface Water Working Group and from a similar European community of scientists, engineers, and users.

“The ability to measure, monitor, and forecast the U.S. and global supplies of fresh water is another high-priority concern. Agencies, through the NSTC (National Science and Technology Council), should develop a coordinated, multi-year plan to improve research to understand the processes that control water availability and quality, and to collect and make available the data needed to ensure an adequate water supply for the Nation's future.”

Alsdorf, D. and D. Lettenmaier, Science, , Alsdorf, D., D. Lettenmaier, C. Vörösmarty, & the NASA Surface Water Working Group, EOS Transactions AGU, , The WatER Mission

Why do we care about streamflow? Rivers are the Earth’s arteries Rivers are a primary source of water for human consumption, food production, transportation, and many other uses Riparian corridors, including wetlands, are extraordinarily productive and diverse biologically Much of the world’s population lives in flood plains Rivers also pose major hazards to human life and well being (due to both floods and droughts)

A thumbnail sketch of global water issues  Approximately 25,000 people die each year due to floods  2.2 to 5 million die annually from preventable water-related diseases.  Drought losses globally have exceeded $300B over the last decade  More than 1.2 billion have inadequate drinking water (poor quality, insufficient quantity)  Twice that many (2.5 billion) lack adequate sanitation facilities.  Approximately 10% of the annual discharge of the world’s rivers is used consumptively, and several major continental rivers (e.g., Colorado, Nile, Yellow) are dry for at least part of the year  The quality of many of the world’s rivers has been seriously degraded by a combination of pollution, land cover change, dams, and other factors  Science and technology solutions to water problems will come from the acquisition of data about river discharge, and the storage of water in reservoirs, lakes, and wetlands. Water cycle models will be greatly improved, thus permitting the prediction of water availability and hazards.

Although at least 4% of the earth’s surface is covered by wetlands and floodplains, none of this area is gauged because diffusive flow prohibits in-channel gauging practices. Reservoirs, lakes and streams in non-industrialized regions are also unmeasured. How does this lack of measurements limit our ability to predict the land surface branch of the global hydrologic cycle? e.g., In locations where gauge data is available, GCM precipitation and subsequent runoff miss streamflow by 100%; the question is unanswered for ungauged wetlands, lakes, and reservoirs throughout the world. The Problem: Some Resulting Science Questions: 100% Flooded! OBS Runoff (mm/day) Models Jan Jul Dec What is the role of wetland, lake, and river water storage as a regulator of biogeochemical cycles, such as carbon and nutrients? e.g., Rivers outgas as well as transport C. Ignoring water borne C fluxes, favoring land-atmosphere only, yields overestimates of terrestrial C accumulation The Solution: Instrument technology that provides both spatial area and elevation of the water surface, i.e., the Ka-band interferometric altimeter. This JPL technology will provide decimeter-scale pixels of the water surface with centimeter-scale elevations. Hydraulic measurements of h, dh/dt, dh/dx, and inundated area will all be collected.

Societal Issues Addressed by WatER  Floods and Hazard Prediction  Water Resource Management  Health and Water Bourne Diseases

Flooding Issues Flooding imposes clear dangers, but the lack of water heights and inundation mapping during the passage of the flood wave limit important hydraulic modeling that would otherwise predict the zones of impact. Essentially, can we predict flooding hazards which could be used to understand the consequences of land use, land cover, and climatic changes for a number of globally- significant, inhabited floodplains? Estimated Costs: $1.9 Billion Over 100 dead in Europe, alone Prague Kentucky India China Black Sea These are the global floods from 2002, alone!

Water Management and Availability What are the implications for global water management and availability? Ability to globally forecast freshwater availability is critical for population sustainability. Water use changes due to population are more significant than climate change impacts. Predictions also demonstrate the complications to simple runoff predictions that ignore human water usage (e.g., irrigation). Vörösmarty, C.J., P. Green, J. Salisbury, and R.B. Lammers, Global water resources: Vulnerability from climate change and population growth, Science, 289, , For 2025, Relative to 1985

Trans-Boundary Water Management Many of the earth’s major rivers cross international boundaries, which confuse decision processes regarding river management. In many such cases, information regarding water storage, discharge, and diversions in one country that affect the availability of water in others is not freely available (e.g., the Nile, Jordan, Indus, and Mekong). In fact, hydrological observations that have implications for water management often are closely guarded, and are only released, if ever, many years after any practical utility has passed. A surface water mission would bring about a wholesale change in the availability of a huge volume of data with implications for water management, access to which would be unconstrained by international boundaries.

Water Bourne Diseases Major health issues are also tied to fresh water. Disease vectors such as malaria are a function of mosquito habitats, which in turn, are directly related to water surface areas. Yet, we do not have any archival or contemporary mapping of these highly dynamic and sometimes ephemeral water bodies. About 3,000,000 people die each year from Malaria

From the standpoint of global water issues, what would be the impact of the proposed WatER mission? Freely available data on water storage for water bodies larger than ~1 km Capability to produce river discharge estimates for many rivers with width > ~ m Major implications for the ability to predict floods and droughts globally Elimination of “competive advantage” of upstream countries in trans-boundary rivers Implications for global markets (especially food)

Possible role and implications of a global surface water mission Free and open exchange of global hydrologic data (which presently does not exist) Understanding how reservoirs are operated (presently there is no coherent data base for reservoir storage) Water and human health (2 billion incidences of water borne diseases per year globally!)

WatER and Us The impact of water availability on mankind is obviously great. Thousands of people perish each year because of floods whereas over a billion are without adequate drinking water [Gleick, 2003]. Indeed, population growth by 2025 is expected to impact water availability much more greatly than the impacts of greenhouse warming on water systems [Vörösmarty et al., 2000]. Thus, water resource issues will have large effects on many of the world’s major decisions in the coming decades. However, lacking measurements of surface water storage changes and fluxes limits predictive capabilities regarding future water availabilities.