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Estimation of Herbaceous Fuel Moisture Content Using Vegetation Indices and Land Surface Temperature from MODIS Data
Institut des Sciences de l'Environnement (ISE), Faculté des Sciences et Techniques, Université Cheikh Anta Diop de Dakar, B.P. 5005 Dakar-Fann, Sénégal
Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE), Université Aix-Marseille III, CNRS UMR 7330, Europôle de l'Arbois, B.P. 80, F-13545 Aix-en-Provence cedex 4, France
Laboratoire d'Enseignement et de Recherche en Géomatique (LERG), Ecole Supérieure Polytechnique (ESP)/FST, Université Cheikh Anta Diop de Dakar, B.P. 5005 Dakar-Fann, Sénégal
Section of Geography, Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen, Oster Voldgade 10, 1350 Copenhagen K, Denmark
Current Address: ICRAF (World Agroforestry Centre), SD6 United Nations Avenue, P.O. Box 30-677 Gigiri, Kenya
Current Address: Centre de Bio-Archéologie et Ecologie (CBAE), Laboratoire Paléoenvironnements et Chronécologie (PALECO), Ecole Pratique des Hautes Etudes, UMR 5059, Institut de Botanique, 163 rue A. Broussonnet, F-34090 Montpellier, France
* Author to whom correspondence should be addressed.
Received: 21 March 2013; in revised form: 25 April 2013 / Accepted: 25 April 2013 / Published: 24 May 2013
Abstract: The monitoring of herbaceous fuel moisture content is a crucial activity in order to assess savanna fire risks. Faced with the difficulty of managing wide areas of vegetated surfaces, remote sensing appears an attractive alternative for terrestrial measurements because of its advantages related to temporal resolution and spatial coverage. Earth observation (EO)-based vegetation indices (VIs) and the ratio between Normalized Difference Vegetation Index (NDVI) and surface temperature (ST) were used for assessment of herbaceous fuel moisture content estimates and validated against herbaceous data collected in 2010 at three open savanna sites located in Senegal, West Africa. EO-based estimates of water content were more consistent with the use of VI as compared to the ratio NDVI/ST. Different VIs based on near-infrared (NIR) and shortwave infrared (SWIR) reflectance were tested and a consistent relationship was found between field measurements of leaf equivalent water thickness (EWT) from all test sites and Normalized Difference Infrared Index (NDII), Global Vegetation Moisture Index (GVMI) and Moisture Stress Index (MSI). Also, strong relationships were found between fuel moisture content (FMC) and VIs for the sites separately; however, they were weaker for the pooled data. The correlations between EWT/FMC and VIs were found to decrease progressively as the woody cover increased. Although these results suggest that NIR and SWIR reflectance can be used for the estimation of herbaceous water content, additional validation from an increased number of study sites is necessary to study the robustness of such indices for a larger variety of savanna vegetation types.
Keywords: herbaceous moisture content; vegetation indices; land surface temperature; remote sensing; MODIS; Senegal
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Sow, M.; Mbow, C.; Hély, C.; Fensholt, R.; Sambou, B. Estimation of Herbaceous Fuel Moisture Content Using Vegetation Indices and Land Surface Temperature from MODIS Data. Remote Sens. 2013, 5, 2617-2638.
Sow M, Mbow C, Hély C, Fensholt R, Sambou B. Estimation of Herbaceous Fuel Moisture Content Using Vegetation Indices and Land Surface Temperature from MODIS Data. Remote Sensing. 2013; 5(6):2617-2638.
Sow, Momadou; Mbow, Cheikh; Hély, Christelle; Fensholt, Rasmus; Sambou, Bienvenu. 2013. "Estimation of Herbaceous Fuel Moisture Content Using Vegetation Indices and Land Surface Temperature from MODIS Data." Remote Sens. 5, no. 6: 2617-2638.