Quantitative assessment of agricultural drought risk in southeast Gansu province, northwest China

Abstract

The sector that suffers the most directly from drought is agriculture, and drought is expected to become more serious in the context of global warming. Effectively evaluating the agricultural drought risk is fundamental to establishing present water resource management and guaranteeing food security. Therefore, southeast Gansu province was selected for this study as a typical region for which to analyze drought trends and assess agricultural drought risk. Trends for the period from 1967 to 2018 were analyzed at 21 locations by using the Mann-Kendall method, and drought was quantified by using the Standardized Precipitation Evapotranspiration Index (SPEI). Spatial characteristics of the agricultural drought risk that emphasized the combined role of hazards and vulnerability were investigated at a 1-km grid scale. Results showed that the annual SPEI exhibited a nonsignificant increasing trend from 1967 to 1990 but that after 1990, the SPEI showed a steep downward trend of 0.1 per decade. The drying trend from 1990 to 2018 was mainly attributed to a significant increase in the reference evapotranspiration. Approximately 16.1% of the agricultural areas are exposed to an extremely high risk and 42.2% are exposed to high risk of drought. Moreover, 56.7% of the extremely high-risk agricultural areas are located in the Longnan region, which strongly suggests that more attention must be paid to preparedness for and mitigation of drought in the Longnan region. This study offers a scientific approach to evaluating the risk of agricultural drought in dry agricultural regions.