National Drought Monitoring System for Drought Early Warning Using Hydrologic and Ecologic Observations from NASA Satellite

Data

(Project Years 2 and 3, only)

G. Robert Brakenridge, Co-InvestigatorDartmouth Flood Observatory

Depts. Geography and Earth SciencesDartmouth College

Hanover, NH 03755 USA

DFO Contributions to the National Drought Monitor

1) Validation of “Hydrologic Drought”, using MODIS and ASTER

2) Documentation/Quantification of surface water impact of Drought

3) Testing methods for long-term incorporation of NASA satellite-derived surface water information into the Drought Monitor

Example: ASTER Drought Map SeriesOklahoma/Texas Border

Period of Extreme Drought, July 18, 2006 to October 31, 2006

Stream gaging and soil moisture measurement or modeling provide information concerning two aspects of hydrologic drought.

Meanwhile, NASA orbital remote sensing is well-posed to provide data concerning drought-related changes in actual surface water supply: areal extent and depth of rivers, reservoirs, and lakes and ponds. This example uses ASTER.

Map series shows surface water as detected by ASTER on September 30, 2006 in pale blue (during drought) on top of reference water from May 3, 2004 in dark blue. Black lines are the borders of the USGS 1:250,000-scale Hydrologic Units of the United States. Rivers are shown in pale grey (USGS ERF1_2 -- Enhanced River Reach File 2.0). DCW roads and towns are also shown. Map projection: UTM Zone 15 WGS 84. Shaded relief background from SRTM.

The following are sample portions of first draft maps, to be much modified!

ASTER-imaged reservoir area reductions north of Sulphur Springs.

Many smaller water bodies are shown as absent; this result is not yet validated.

ASTER-imaged reservoir area reductions west of Winnsboro

ASTER-imaged Red River area reductions

Shrinkage of smallstock ponds southwestof Sulphur Springs.

Other dry ponds (dark blue) not yet validated.

Initial Work Strategy, First DFO project Year: 1. Use ASTER change detection, water classification, and vectorization technologies to measure at 10 m spatial resolution changes in water surface area for USDM hydrologic drought-affected areas.

2. Use simultaneous MODIS 250 m band data in same regions and times to determine MODIS-based signal of same changes.

3. Use MODIS to track evolution in time of surface water impact of drought for same regions and same USDM drought event. Produce time series of surface water change.

4. Use ASTER-based water depth algorithms to measure water depth changes, to accompany data on surface water areal extent, and with emphasis on small reservoirs.