Understanding Agriculture Drought Propagation and the Controlling Factors

Drought propagation is the change in drought signals when it moves from meteorological drought to agriculture or hydrological drought. It is important not only to quantify the process and characteristics of drought propagation but also to understand the various controlling factors of the phenomenon, including those of climate, catchment, and human interference. Both statistical analysis and simulation modeling have been used to study drought propagation. Hydrological drought propagation in terms of water storage (in both surface water reservoirs and aquifers) and streamflow has been studied extensively; meanwhile studies on agriculture drought propagation are mostly limited to statistical analysis of crop yield, evapotranspiration, and soil moisture. In particularly, efforts have been made to understand the process of agriculture drought propagation in terms of soil moisture, and few studies consider the impact of plant physiology, especially how different crop growth stages affect (either mitigate or enhance) the drought propagation process. The purpose of this study is to assess agriculture drought propagation in terms of soil moisture and crop water requirement deficit and identify a better drought indicator. The Soil-Water-Atmosphere-Plant (SWAP, a one-dimension physically based agro-hydrological model) will be used to simulate soil moisture and crop water deficit along the crop growth in different parts of Illinois. The results from the model will be used to quantify the drought index, which will be used to analyze agriculture drought propagation and identify the major factors including climate, catchment, crop type, and crop stage that characterize the propagation process.