Developing the vegetation drought response index for South Korea (VegDRI-SKorea) to assess the vegetation condition during drought events

Authors: NAM, WON-HO - Hanyang University; TADESSE, TSEGAYE - University Of Nebraska; WARDLOW, BRIAN - University Of Nebraska; HAYES, MICHAEL - University Of Nebraska; SVOBODA, MARK - University Of Nebraska; HONG, EUNMI - Orise Fellow; Pachepsky, Yakov; JANG, MIN-WON - Gyeongsang National University

Submitted to: International Journal of Applied Earth Observation and Geoinformation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2017
Publication Date: 10/15/2018
Citation: Nam, W., Tadesse, T., Wardlow, B., Hayes, M., Svoboda, M., Hong, E., Pachepsky, Y.A., Jang, M. 2018. Developing the vegetation drought response index for South Korea (VegDRI-SKorea) to assess the vegetation condition during drought events. International Journal of Applied Earth Observation and Geoinformation. 39(5):1548-1574.

Interpretive Summary: Climate-based drought indices using point-based meteorological observations have been used to help quantify drought impacts on the vegetation in South Korea. However, these indices are point-based, and their suitability for mapping drought stress is limited. The objective of this study was to develop a both weather and satellite data-based hybrid drought index called the Vegetation Drought Response Index for South Korea (VegDRI-SKorea) that could improve the spatial resolution of agricultural drought monitoring on a national scale The VegDRI-SKorea is based machine -learning modeling approach that jointly analyzes remote sensing data, weather-based drought indices, and landscape characteristics to develop accurate mapping of droughts. We demonstrated that the hybrid drought index improved the more spatially detailed drought patterns compared to the station-based drought indices and resulted in a better understanding of drought impacts on the vegetation conditions. Results of this work are expected to be used by industry consultants and policy makers who utilize the information on local and regional drought risks for management and mitigation actions.

Technical Abstract: Drought poses significant water and food security concerns in many parts of the world and can lead to negative agricultural, economic, and environmental impacts. The Vegetation Drought Response Index (VegDRI) approach has the flexibility to be adapted for other regions of the world using the climate, satellite, and biophysical datasets that are available for those regions. A drought index with detailed spatial-resolution information on drought-affected vegetation conditions is essential to improve the country’s drought monitoring capabilities, which are needed to help develop more effective adaptation and mitigation strategies. In this study, a new VegDRI-SKorea model was developed for South Korea to monitor agricultural drought conditions. The VegDRI-SKorea utilizes a classification and regression tree modeling approach that collectively analyzes remote sensing data, climate-based drought indices, and biophysical variables that influence the drought-related vegetation stress. VegDRI-SKorea has a good performance to characterize local-scale variations in drought conditions across the growing season. In addition, the results demonstrated that the more spatially detailed drought patterns that are depicted at a 250-m resolution in the VegDRI-SKorea maps can help in improving the characterization of the vegetation conditions as compared to the commonly used satellite-based drought index and station-based drought index. The VegDRI-SKorea tool can be used for drought monitoring by agricultural producers, decision makers relying on early warning information, policy makers, and other stakeholders to improve management decisions.