507
21
Remote Sensing of
Soil and Vegetation
Moisture from Space
for Monitoring Drought
and Forest Fire Events
Lingli Wang, John J. Qu, and Xianjun Hao
CONTENTS
21.1 Introduction .................................................................................................. 508
21.2 Literature Review .........................................................................................509
21.2.1 Drought Definition ...........................................................................509
21.2.2 Drought Indices ............................................................................... 510
21.2.3 Satellite Remote Sensing for Monitoring Drought .......................... 510
21.3 NMDI: A Normalized Multiband Drought Index for Monitoring Soil
and Vegetation Moisture ............................................................................... 511
21.3.1 Formation of NMDI ......................................................................... 512
21.3.2 Validation .......................................................................................... 513
21.3.2.1 Soil Drought Monitoring ................................................... 513
21.3.2.2 Vegetation Drought Monitoring ......................................... 515
21.4 Application of the NMDI for Drought Monitoring ...................................... 516
21.4.1 Methodology ..................................................................................... 516
21.4.1.1 Study Area and Data .......................................................... 516
21.4.1.2 Methods ............................................................................. 517
21.4.2 Results and Discussion ..................................................................... 517
21.4.2.1 Vegetation Water Indices and Drought Condition Analysis ....517
21.4.2.2 Fire Activities and Drought Conditions ............................. 521
21.5 Applications of the NMDI for Active Forest Fire Detection ........................ 523
21.5.1 Study Area and Data ......................................................................... 523
21.5.2 Methodology for Fire Detection ....................................................... 524
21.5.3 Indices Testing and Discussion of Results ........................................ 526
21.5.3.1 Georgia Fires ..................................................................... 526
21.5.3.2 Greek Fires ......................................................................... 529
21.6 Conclusions ................................................................................................... 532
References .............................................................................................................. 533