Comparing Agriculture-Related Characteristics of Flash and Normal Drought Reveals Heterogeneous Crop Response

Abstract

Despite rapid progress in the burgeoning field of flash drought research, few studies directly compare the differences in characteristics between flash drought (commonly understood as quick, rapid-onset drought) and drought traditionally defined as slow-moving (henceforth normal drought), particularly over agricultural regions where drought effects may be economically the most disastrous. In this study, flash and normal drought events are identified using reanalysis of soil moisture in the data-rich agricultural region of the California Central Valley for investigation of characteristics related to agriculture. In particular, we investigate the relative duration of pixels in drought events, the correlation of drought intensity with vegetation condition, the impact of aridity on vegetation response and drought, and the differences in the different characteristics between rainfed and irrigated agriculture. Overall, we found considerable differences between flash and normal drought, particularly in their spatial distributions and behavior in relation to aridity. Flash droughts even indicate a counterintuitive improvement in vegetation condition in the northern, more humid regions, likely due to the release of growth limiting factors (e.g., below-optimum temperature and radiation) associated with drought. Results also indicate improvements in vegetation conditions during normal drought for irrigated land over rainfed, highlighting the importance of irrigation as a drought protection strategy in agriculture.