Identification drought extent based on NVSWI using landsat data: A case study of Iaşi county

Abstract

Climate change is one of the most significant issues facing the world because it is predicted to alter climate patterns and increase the frequency of extreme weather events, such as drought. Drought is one of the most widespread and least understood natural phenomena. Drought can be monitored using the climatic variables like rainfall and temperature. The droughts are the phenomena which affect large areas and remote sensing data covering large territory can be used to assess the droughts impact and their extent. In this study was used remote sensing images from the Landsat 8 Operational Land Imager (OLI), taken in august and November 2016 and april 2017. To evaluate drought in this paper, for Iasi county, Normalized Vegetation Supply Water Index (NVSWI), was used. This index is based on Normalized Difference Vegetation Index (NDVI) and on Land surface temperature (LST). This research has shown that NVSWI has more notable results in assessing droughts during seasons with a high degree of vegetation coverage, this is why the results for February were not taken into account because the results were not considered to be satisfying. Larger areas affected by moderate drought were reported for November, and for August and April prevailed areas of slight drought. It can be concluded that NVSWI is not recommended for the assessment of drought-affected areas during winter, because in obtaining the values of this index an important role is given by NDVI. In the same situation, Normalized Difference Drought Index (NDDI) is also found. Taking into account the results of this study and the characteristics of the study area, it is recommended that the Soil Moisture Deficit Index (SMDI) and the Standardized Precipitation Evapo-transpiration Index (SPEI) be used in the future for the analysis of drought-affected areas.