Keeping it simple: Monitoring flood extent in large data-poor wetlands using MODIS SWIR data

• Published in: International journal of applied earth observation and geoinformation Vol. 57; pp. 224 - 234
• Main Authors: Wolski, Piotr, Murray-Hudson, Mike, Thito, Kgalalelo, Cassidy, Lin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2017
• Subjects: Hydroperiod; Inundation; Landsat; MODIS; Okavango Delta; Hydroperiod; Inundation; MODIS; Okavango Delta; Landsat
• ISSN: 1569-8432; 1872-826X
• DOI: 10.1016/j.jag.2017.01.005

•We develop a series of 2000–2014 inundation maps for the Okavango Delta, Botswana.•For inundation mapping, SWIR proves superior to indices such as NDVI, NDWI, MNDWI.•Inundation classification based on thresholding of MODIS MCD43A4 SWIR band.•Threshold for each scene based on reflectance of end-members of inundation range.•The method provides a very good accuracy and is suitable for automated processing. Characterising inundation conditions for flood-pulsed wetlands is a critical first step towards assessment of flood risk as well as towards understanding hydrological dynamics that underlay their ecology and functioning. In this paper, we develop a series of inundation maps for the Okavango Delta, Botswana, based on the thresholding of the SWIR band (b7) MODIS MCD43A4 product. We show that in the Okavango Delta, SWIR is superior to other spectral bands or derived indices, and illustrate an innovative way of defining the spectral threshold used to separate inundated from dry land. The threshold is determined dynamically for each scene based on reflectances of training areas capturing end-members of the inundation spectrum. The method provides a very good accuracy and is suitable for automated processing.