Publications

Zhao, Z; Wang, KC (2021). Capability of Existing Drought Indices in Reflecting Agricultural Drought in China. JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES, 126(8), e2020JG006064.

Abstract
A variety of drought indices have been constructed to monitor agricultural drought using ground-based observations and satellite data. The drought indices focus on diverse aspects of agricultural drought and may have diverse applicability in different regions. We calculated seven popular drought indices and evaluated their performances on monitoring agricultural drought in the main agricultural regions of China (i.e., Northeast China, the North China Plain, the middle-and-lower reaches of the Yangtze River, and the Sichuan Basin). The independent assessment data used here included three aspects: soil moisture, vegetation photosynthesis (i.e., sun-induced chlorophyll fluorescence, SIF), and crop yield. Results show that drought indices with one-month time scale are more sensitive to topsoil moisture than drought indices with longer time scales. Drought indices based on regular meteorological data (DImet) and synthesized drought indices (DIsyn) show better performances on capturing drought impacts on the SIF than other drought indices. DIsyn is more appropriate for predicting drought impact on crop yield than other drought indices. In addition, drought impact on vegetation photosynthesis and crop yield is lessened in humid or irrigated regions. Our study sheds light on agricultural drought researches in the future. Plain Language Summary Agricultural drought intensively affects crop growth and food security, and may be more severe under the global warming in the future. However, the different drought indices may bring in incomparable results because of inconsistent definitions of agricultural drought and different algorithms. Our study evaluated the capabilities of seven drought indices to detect drought impact in four major agricultural regions of China. Three aspects of agricultural drought were selected as assessment data: soil moisture, vegetation photosynthesis, and crop yield. Our results show that drought indices based on meteorological data generally show better performances in capturing drought impact, and incorporating abundant data sources will extend the applicability of drought indices to detect different aspects of agricultural drought impact. The impact of drought on vegetation is negligible in regions with humid climate or irrigation. This study shows the applicability of different types of drought indices to monitor agricultural drought impact in different regions, which is instructive for the applications of drought indices and the development of drought index in the future.

DOI:
10.1029/2020JG006064

ISSN:
2169-8953