Dennis P. Lettenmaier Qiuhong Tang Eric Rosenberg Department of Civil and Environmental Engineering University of Washington for NASA Water Management Program PI Meeting Adelphi, Maryland September 17, 2009 Improving water resources management in the western U.S. through use of remote sensing data and seasonal climate forecasts

Project objectives Assess the potential for NASA remote sensing data to improve the performance of water supply forecasts for water management decisions. –Remote sensing snow cover extent products used in prediction of snowmelt runoff processes for reservoir and other water management decisions. –Satellite-based evapotranspiration (ET) data for crop water use estimation –Primary partner is CA Department of Water Resources

MODIS Snow Cover for Water Supply Prediction Aqua Terra (NASA) Snow Data UW Hydrological Forecast System Snowpack Initial Condition Reservoir Regulation

Snow stations and MOD10A1 Data availability: the percentages of the total stations or pixels for which snow data was available Winter Summer Snow Stations MOD10A1 Classification fraction: the percentages of the total days for which MOD10A1 was either snow covered or snow free, and the station observation was present. Snow stations are from SNOTEL and the California Cooperative Snow Surveys network Feather River Oroville Reservoir Southwest Northwest

Evaluation of MODIS snow cover Mis-classification fraction Classification fraction Misclassification fraction: the percentages of the total days/stations for which MOD10A1 did not match the station observation. ablation accumulation

Snow cover areal (SCA) SCA: snow cover percentage of total area in the Feather River basin, California. SCA (%) Ablation period

Predicted Streamflow at Oroville Reservoir Overestimated (without MODIS) Improved (with MODIS) outlier Year:

Retrospective streamflow forecasts Mean Absolute Error (MAE) Two-week forecasts Seasonal forecasts Year: Seasonal forecast: streamflow forecasts from forecast date through July 31 Two-week forecast: two-week lead-time streamflow forecasts Inclusion of MODIS data reduced forecast errors in 70% of the two- week forecasts and 85% of the seasonal forecasts in the ablation period.

Hybrid statistical-dynamical seasonal runoff forecasts Can model-simulated snow states and MODIS SCA data be adapted to the regression-based forecasting system used by California’s Department of Water Resources? Study focused on 14 watersheds located in the (blue (green) Sacramento River (blue), San Joaquin River (green), and Tulare Lake (red) (red) hydrologic regions, which together are responsible for ~60% of the state’s runoff. Upper Sacramento Feather Yuba American Cosumnes Mokelumne Stanislaus Tuolomne Merced San Joaquin Kings Kaweah Tule Kern

Potential Benefits Improve forecast skill by enhancing the spatial representation of snow states. Alleviate pressure to conduct labor-intensive snow surveys. Provide the ability to generate forecasts late in the melt season, when even high-elevation snow sensors are laid bare, but forecasts are nonetheless valuable. MODIS image on Jun 3, 2006… snow indicated in white, clouds indicated in blue. Feather American Tuolomne Merced

Hybrid statistical-dynamical seasonal runoff forecasts – Feather River, CA CA DWR’s forecasts for April-July runoff rely on manual measurements of SWE at snow courses throughout each watershed (left, for the Feather). Problems can occur late in the year when snow remains at high elevations, but not at snow course Possible approach is to regress seasonal flow on VIC-simulated SWE (whicn includes high elevations where snow remains) rather than observed SWE (right). Currently 1/8 degree; higher resolution (1/16°) in progress.

Preliminary Results… Sacramento River Feather (1781 taf) +100 Yuba (1005 taf) American (1240 taf) U. Sacramento (2494 taf) FMMJJA Skill compared in plots of 10th and 90th percentiles of resulting residuals, provided as a percentageof mean annual flow (shown in parentheses). Blue = model-based,black = ground-based. Blue = model-based, black = ground-based.FMMJJAFMMJJAFMMJJA

Preliminary Results… San Joaquin River Mokelumne (460 taf) +100 Stanislaus (702 taf) Cosumnes (126 taf) FMMJJA Skill compared in plots of 10th and 90th percentiles of resulting residuals, provided as a percentageof mean annual flow (shown in parentheses). Green = model-based,black = ground-based. Green = model-based, black = ground-based.FMMJJAFMMJJA

Preliminary Results… San Joaquin River Merced (632 taf) +100 San Joaquin (1254 taf) Tuolomne (1220 taf) FMMJJA Skill compared in plots of 10th and 90th percentiles of resulting residuals, provided as a percentageof mean annual flow (shown in parentheses). Green = model-based,black = ground-based. Green = model-based, black = ground-based.FMMJJAFMMJJA

Preliminary Results… Tulare Lake Kaweah (286 taf) +100 Tule (64 taf) Kern (461 taf) Kings (1224 taf) FMMJJA Skill compared in plots of 10th and 90th percentiles of resulting residuals, provided as a percentageof mean annual flow (shown in parentheses). Red = model-based,black = ground-based. Red = model-based, black = ground-based.FMMJJAFMMJJAFMMJJA

Backward extension in time – pre-MODIS Greatest obstacle is lack of long-term satellite data to develop climatology: - MODIS data goes to 1999 only -AVHRR data considered “meteorological” and not well archived - NESDIS maintains a SCA record dating back to 1966, but its resolution is too coarse. - NOHRSC has 1 km SCA records from the late 1980s, but data are sporadic and generated by evolving set of algorithms. The Terra satellite (top), launched in Dec 1999, and the Aqua satellite, launched in May 2002.

Land Long-Term Data Record Recent NASA project to produce a prototype climate data record from AVHRR and MODIS instruments: Pedelty J, Devadiga S, Masuoka E, Brown M, Pinzon J, Tucker C, Roy D, Ju J, Vermote E, Prince S, Nagol J, Justice C, Schaaf C, Liu J, Privette J, Pinheiro A (2007) Generating a long-term land data record from the AVHRR and MODIS instruments IGARSS, July 23–27, Barcelona 0.05° (~4 km) AVHRR data (1981–1999); will include year of AVHRR from 2000s for calibration w/ MODIS

Snowcode Estimates daily snow cover, including periods of cloudy conditions by temporal filtering and interpolation: Zhao H, Fernandes R (2009) Daily snow cover estimation from Advanced Very High Resolution Radiometer Polar Pathfinder data over Northern Hemisphere land surfaces during 1982–2004. J Geophys Res 114(D05113):1–14 Ongoing effort to apply snowcode to LTDR data, and extract fractional snow cover to match higher resolution of MODIS data.

UW Remote Sensing Data Assimilation & Seasonal Climate Forecasts Daily updating over the Western U.S. UWSDAS Website: UWSDAS leverages heavily from the University of Washington’s west-wide hydrologic forecast system.

Summary Evaluations show that MODIS snow product has the greatest misclassified fractions during the ablation period and at the beginning of the snow accumulation period. VIC application with and without MODIS SCA updating showed that the greatest improvements occurred during the snow ablation season, with little to no improvement otherwise. Inclusion of MODIS data reduced forecast errors in 70% of the two-week forecasts and 85% of the seasonal forecasts in the ablation period.

Satellite-based ET for water management Aqua Terra MODIS GOES Albedo Emissivity Temperature Surface reflectance Vegetation indices Land cover … Hourly surface radiation budget (SRB) data Water management model Irrigation withdrawal Endangered Species Drought Monitoring

Satellite-based Near-real-time ET Constant-EF hypothesis ( EF=ET/Q; Q: available energy ) EF instantaneous = EF day Closest available data rule For days when the retrieval data (Ts) is unavailable (mostly due to cloudy conditions), the data (Ts) for the closest available day is used instead. Time lag: 3 days to 1 week The latency is controlled by release of the MODIS products. It could be reduced to about 2 days through use of MODIS Rapid Response products. Key features The primary inputs (MODIS products and NOAA/NESDIS surface radiation budget products ) are available both near real-time and retrospectively. Please see our poster (Tang and Lettenmaier, 2009) for more information.

Evaluation of MODIS ET Bias: -7% for clear sky; -12% for all days from April 1 to October 31, 2004 Flux tower observed and satellite-based ET day at KL04 (an irrigated site) KL04 Klamath, OR Acknowledgement: flux tower data are from Oregon State University

MODIS ET vs Landsat ET MODIS ET Landsat METRIC Bias: ~1 mm/day METRIC: Mapping Evapotranspiration at high Resolution and with Internalized Calibration KL04 KL03 Irrigated Non-irrigated Klamath Reclamation Project

Crop water use and irrigation water use Net irrigation consumption (NIC): NIC = ET actual - ET natural NIC ET actual ET natural NIC (MODIS) NIC (VIC) Obs. Irrigation Time series of estimated NIC and observed net irrigation supply. Dry year restricted irrigation Time series of MODIS ET, VIC simulated actual and natural ET for the irrigation areas of the Klamath Reclamation Project from 2001 to 2005.

Impacts of agriculture on Lake Lake Irrigation Area Klamath Project Irrigation (Irr) With Irr Without Irr ~0.5 m water level Observed Upper Klamath Lake

Satellite-based ET Monitoring for Water Management Upper Klamath Basin Yakima Basin Satellite-based ET monitoring in the Yakima Basin, WA (left) and Upper Klamath Basin, OR (right).

Crop Water Use Monitoring Daily updating. 3 days to 1 week latency Websites: U.S. WA: Satellite-based ET product from 2001 to 2008 over the continental United States are available at the U.S. website.

Summary A satellite-based near real-time ET approach for water management is illustrated. Applications of the satellite-based ET product show that NASA remote sensing data can help in improving reservoir/lake management and related water management in the western U.S. The retrospective and near-real-time ET products are ready to provide crop water consumption and irrigation water requirement information for USDA and Bureau of Reclamation.

Conclusions Our research has demonstrated substantial improvements in hydrological modeling and observations which are promising in Western water management. It is urgent to transfer these research results into operations, and transfer the water and climate forecast information to water users such as USDA and Bureau of Reclamation. The transition of these research results for water user, we can foresee, will have substantial potential for economic gains.

Outreach and User Interactions Continued communication with CA DWR personnel to tailor MODIS products to their specific needs: Art HinojosaChief of Hydrology Branch David RizzardoChief of Forecasting Section Adam SchneiderSenior Engineer Aaron MillerSenior Engineer Boone LekSenior Engineer John KingSenior Engineer Steve NemethSenior Engineer

Current and Potential Users – Crop water use products Water management –Decision support tool –Agricultural impacts on lake –Potential ET forecast –Potential users Water budget study