Some thoughts on SWOT water resources applications

Dennis P. Lettenmaier

Department of Civil and Environmental EngineeringUniversity of Washington

WaTER/SWOT SWG meetingParis

February 1, 2008

What are the challenges in global water management?

• Population growth and lifestyle change, leading to increased water demand

• Transboundary conflicts

• Environmental change–Land Cover–Climate

Forest/Woodland

Shrubland/grassland

Cropland

1990s land cover (U MD) Global Potential Vegetation (Ramankutty and Foley)

Uruguay River basin land cover change – potential vegetation vs 1990s

Land cover change in the Mekong River basin

Qori Kalis Glacier, Peru 1978 and 2002. Visual courtesy of Lonnie Thompson, from Barnett et al (Nature, 2005)

Impacts of reservoirs on the water cycle?

~1900

2000

Construction of dams has vastly altered the water cycle by:•Altering the seasonal cycle, and annual amount of discharge (6 major global rivers, including the Colorado, no longer flow at their mouths)

•Increasing the time of travel through the channel system

•Changing the quality of rivers, and constituents and physical characteristics of continental river discharge

•Transporting water within and between rivers basins, and altering its partitioning (usually meaning increased evapotranspiration)

Some examples

Regulated Flow

Historic Naturalized Flow

Estimated Range of Naturalized FlowWith 2040’s Warming

Figure 1: mean seasonal hydrographs of the Columbia River prior to (blue) and after the completion of reservoirs that now have storage capacity equal to about one-third of the river’s mean annual flow (red), and the projected range of impacts on naturalized flows predicted to result from a range of global warming scenarios over the next century. Climate change scenarios IPCC Data and Distribution Center, hydrologic simulations courtesy of A. Hamlet, University of Washington.

Columbia River at the Dalles, OR

Opportunities

• Time series (in near-real time) of elevation, and storage (utilizing surface area as well as stage) of major global reservoirs (note ~2500 in ICOLD data set of large global dams, but ~80,000 in U.S. Army COE data base for U.S. reservoirs

Action: evaluate set of global reservoirs for which such a data set would be feasible (considering surrounding topography, etc.), and evaluate potential for developing storage/elevation relationships over the mission duration

• Time series (in near-real time) of inflow (and/or outflow) to selected major global reservoirs

Action: Evaluate feasibility, number, location

ESA River and Lakes data set (primarily EnviSat/ERS-2)

Visuals courtesy Jerome Benveniste, ESA

Evolving potential for global real-time drought characterization (and prediction) – is there an analogous potential for reservoir storage?

Visual courtesy Eric Wood, Princeton University

• Policy analysis of implications of near-real time reservoir storage data on management of transboundary rivers

Action: need someone to take this on

• Demonstration project for large river flooding?

– Most property damage and loss of life comes from large river (and coastal) flooding (as opposed to flash floods). WaTER flood extent and altimetry should provide basis for updating (via data assimilation) flood forecast models

– Action: Evaluate feasibility and mechanism (problem: there’s always a flood somewhere, but we don’t know where in advance). Possibly partner with a global forecast center?

Applications studies/demos for coastal oceanography

• Storm surge/flooding

• Estuarine (and near coastal) circulation/water quality

• Opportunities for data assimilation?

Action: prioritize, need someone to take on this area