Mapping Droughts Over the Central Highland of Vietnam in El Niño Years Using Landsat Imageries

Abstract

Recently, drought has occurred severely in the Central Highland of Vietnam, particularly during dry seasons of El Niño years. Towards disaster mitigation and sustainable management for drought, this study aims to clarify relationship between drought area detected in dry peak month (March) in years El Niño occurred such as 1998, 1999, 2004, 2005, 2010, 2015, 2016 with local main climate factors and land-uses. Normal Difference Drought Index (NDDI) retrieved from the difference of NDWI and NDVI was used in this study. Results showed that the most severe drought occurred in March 2005 with total area under severe level reached to 1,170 thousand hectares corresponding to 21% of the highland’s total area, and the smallest drought was recorded in March 1999 with total severely affected area of 550 thousand hectares.
Drought-impacted area has increased dramatically for recent years, the largest drought-impacted area was recorded in dry season 2015 with 2,486 thousand hectares, corresponding to 46% of the highland’s total area. If the severe drought area is highly dependent on seasonal average rainfall (R=-0.91), the drought-impacted area is much more dependent on the expansion of residential area and coffee planting area. Therefore, sustainable land-use planning for drought mitigation should be paid attention.