Crop production in the Hexi Corridor challenged by future climate change

Drought is one of the costliest natural hazards and the main factor of concern impacting crop growth in the arid Hexi Corridor in Northwest China. However, the inter-relationship between meteorological drought severity and crop yield is seldom studied across this region. In this study, two multi-scalar drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation-Evapotranspiration Index (SPEI) are employed to monitor the evolution of drought condition in the Hexi Corridor. We examined (a) the historical drought evolution of the Hexi Corridor since 1970s; (b) the possible future drought tendency under different RCP scenarios; and (c) the multi-scale correlation between climatic crop yield and drought indices. The results indicate that the studied area experienced a trend towards warmer and wetter conditions during the last 4 decades and this trend last until the middle 2030s indicated by SPEI. The feasibility of SPEI and SPI for quantifying drought condition and evaluating production loss was tested in the arid and semi-arid regions of northwest of China and SPEI was found more reliable. Correlation analysis between climatic yield and drought indices revealed that the drought condition of the month July detected by 3-month SPEI was the most relevant for the observed changes in climate yield in the Hexi Corridor. By obtaining the critical point of each SPEI-climatic yield curve, we found the different levels of yield vulnerability for the four selected districts, according to which we are able to gain an early prediction of the crop production crisis corresponding to the future drought events.