Remote Sens. 2015, 7(4), 4391-4423; doi:10.3390/rs70404391
Drought Variability and Land Degradation in Semiarid Regions: Assessment Using Remote Sensing Data and Drought Indices (1982–2011)
1
Instituto Pirenaico de Ecología, Spanish National Research Council (IPE-CSIC), Campus de Aula Dei, P.O. Box 13034, E-50059 Zaragoza, Spain
2
Department of Economy, University of Alcala, E-28801 Madrid, Spain
3
Madrid Institute for Advanced Studies in Water (IMDEA-Water), Alcalá de Henares, E-28805 Madrid, Spain.
4
Estación Experimental de Aula Dei, Spanish National Research Council (EEAD-CSIC), Campus de Aula Dei, P.O. Box 13034, E-50059 Zaragoza, Spain
5
Hydrological Modeling & Earth Observation Group, WDRC, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
6
Department of Geography, Mansoura University, 35516 Mansoura, Egypt
*
Author to whom correspondence should be addressed.
Academic Editors: Arnon Karnieli, Soe Myint and Prasad S. Thenkabail
Received: 25 December 2014 / Revised: 26 March 2015 / Accepted: 1 April 2015 / Published: 14 April 2015
(This article belongs to the Special Issue Remote Sensing of Land Degradation in Drylands)
Abstract
We analyzed potential land degradation processes in semiarid regions worldwide using long time series of remote sensing images and the Normalized Difference Vegetation Index (NDVI) for the period 1981 to 2011. The objectives of the study were to identify semiarid regions showing a marked decrease in potential vegetation activity, indicative of the occurrence of land degradation processes, and to assess the possible influence of the observed drought trends quantified using the Standardized Precipitation Evapotranspiration Index (SPEI). We found that the NDVI values recorded during the period of maximum vegetation activity (NDVImax) predominantly showed a positive evolution in the majority of the semiarid regions assessed, but NDVImax was highly correlated with drought variability, and the trends of drought events influenced trends in NDVImax at the global scale. The semiarid regions that showed most increase in NDVImax (the Sahel, northern Australia, South Africa) were characterized by a clear positive trend in the SPEI values, indicative of conditions of greater humidity and lesser drought conditions. While changes in drought severity may be an important driver of NDVI trends and land degradation processes in semiarid regions worldwide, drought did not apparently explain some of the observed changes in NDVImax. This reflects the complexity of vegetation activity processes in the world’s semiarid regions, and the difficulty of defining a universal response to drought in these regions, where a number of factors (natural and anthropogenic) may also affect on land degradation. View Full-TextKeywords:
Standardized Precipitation Evapotranspiration Index (SPEI); NDVI; NOAA-AVHRR; GIMMS; desertification; vegetation recovery
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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MDPI and ACS Style
Vicente-Serrano, S.M.; Cabello, D.; Tomás-Burguera, M.; Martín-Hernández, N.; Beguería, S.; Azorin-Molina, C.; Kenawy, A.E. Drought Variability and Land Degradation in Semiarid Regions: Assessment Using Remote Sensing Data and Drought Indices (1982–2011). Remote Sens. 2015, 7, 4391-4423.
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