Processing of MODIS Vegetation Indices for analysis of agricultural droughts in the southern Ukraine between the years 2000-2012

Abstract: In order to better understand impact of extreme weather events on condition of crop vegetation in Ukraine, analysis of agricultural droughts which occurred in the southern region of Ukraine, between years 2000-2012 was conducted in the current research. Method of the research In the current research, the impact of droughts was analyzed on yearly basis by assessing vegetation conditions and comparing it to soil moisture conditions. Normalized difference vegetation index (NDVI) calculated from satellite imagery was used as a proxy for vegetation activity. Soil moisture data was assessed using Temperature Vegetation Dryness Index (TVDI), which provides a way of assessment of soil moisture in relation to temperature of surface acquired by remote sensing. Prior to analysis crop fields with summer and winter crops were classified. Vegetation and climate variables were summarized for each year of the study and statistical analysis functions were applied to in order to assess relations between them. All calculations and data processing operations were automated using the software solutions developed in the course of the research. Results of the research A a result of the research statistically significant correlation was found between vegetation conditions and soil moisture over the majority of study area and unusually low vegetation conditions coincided in time with unusually dry surface. Trends were predominantly negative for both amount of soil moisture and vegetation conditions, which may suggest that conditions became drier during the study period and this had negative effects on agriculture. Vast areas of summer crops were affected by unusually dry vegetation conditions in years 2003, 2007 and 2012. Droughts in years 2007, 2009 and 2012 had impact on majority of summer crops planted over the study area. Relation to previous researches As in previous researches negative trend was found for vegetation conditions over the study area. The research also approves the occurrence of extreme droughts in years 2003 and 2007. It also complements previous research by finding that winter crops were mostly damaged by droughts in year 2003, while drought in year 2007 has a stronger impact on summer crops. The current research also complements previous approaches of droughts assessment by extending study period till year 2012, which shows abnormal conditions in years 2009 and 2012.