Abstract
Abstract. The Western Region of Paraguay is naturally dry which makes it vulnerable to almost permanent drought events. Hence, low cost drought monitoring is necessary. Therefore, an index derived from satellite image information was used for this purpose. The Normalized Difference Drought Index (NDDI) was used with the objective of studying the characteristics (temporal and spatial distribution) of drought in the Western Region of Paraguay from years 2005 to 2017 and relate drought point values of NDDI to the land use cover of the study area. Terra satellite’s Moderate Resolution Imaging Spectro-radiometer (MODIS) sensor images were used for the calculation of NDDI. The driest month of all years (July) and the wettest month of all years (December) were averaged to analyze spatial tendencies. The NDDI was contrasted spatially with the Land Use Cover of the Western Region to pinpoint the location of the highest values. The year 2015 had the highest value of 0.9847 in agricultural land use in the Department of Boqueron. The NDDI was a good indicator of drought throughout the region and could be a complement for in-situ measurements.
Highlights
The Western Region of Paraguay is characterized by a semiarid climate where cattle ranching is the largest economic activity
Normalized Difference Drought Index (NDDI) was previously studied to be a good indicator of drought in a five-year study in the Great Plains of the United States compared to just using NDVI [3]
The most severe spatial extension of extreme drought according to NDDI were during the years 2010 (Figure 3) and 2016 (Figure 5)
Summary
The Western Region of Paraguay is characterized by a semiarid climate where cattle ranching is the largest economic activity. Another study of fifteen years [4]in a basin was made which found that NDDI was a good measure of drought in large surface studies. A study in Hungary [5] using MODIS imagery and NDDI concluded that the index is sensitive to land cover changes it can overestimate drought. Still, it continues to be a good advantageous low-cost analysis tool. The main objective of this research is to study the characteristics (temporal and spatial distribution) of drought in the Western Region of Paraguay from years 2005 to 2017 and relate drought point values of NDDI to the land use cover of the study area
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