Using Agro-meteorological Indexes to Analyze Variation in Abrupt Drought-flooding Alternation During Cotton Growth Season in Hubei Province

Abstract

【Objective】 Drought and flooding are two abiotic stresses in crops growth. Understanding how they occur in a region is critical to safeguarding its agricultural production. The objective of this paper is to analyze the spatiotemporal variation in abrupt drought and flooding alternation (DFAA) occurring at different growth stages of cotton in Hubei province, aimed to provide reference for ameliorating detrimental impact of these natural hazards on cotton production. 【Method】 An agro-meteorological index named SAPEI -standardized antecedent precipitation evapotranspiration index - was first derived from the renowned SPEI -standardized precipitation evapotranspiration index. It was then used to assess the daily drought and flooding condition in cotton fields across the province, from which we defined and identified individual DFAA events including both abrupt drought-flooding alternations and abrupt flooding-drought alternation. We also collected daily weather data from 26 weather stations across the province and computed their SAPEI, from which we calculated the spatiotemporal variation in DFAA events from 1961 to 2019 at four cotton growth stages: seedling, budding, flowering and boll-forming, and boll opening stages. 【Result】 The SAPEI index was able to describe soil moisture in the cotton field and identify the DFAA events in the province. Regarding the types of DFAA, abrupt drought-flooding alternations had occurred approximately five times the abrupt flooding-drought alternations. It was also found that the frequency and intensity of DFAA varied with the growth stages, most frequent and intensive during flowering and boll-forming stage and least frequent at the budding stage although the intensity during this stage remained relatively high. In contrast, the occurrence of DFAA during the boll-opening stage was least intensive but more frequent. Spatially, the northwest of the province and the Honghu basin were most prone to both abrupt drought-flooding alternation and flooding-drought alternation. Temporally, there were more DFAA events in the 1970s; since the 1990s, DFAA has tended to become more widespread and intensive. 【Conclusion】 Abrupt drought-flooding alternation is the major DFAA form during the growth season of cotton in Hubei province, especially at the flowering and boll-forming stage and in the northwest of the province.

Keywords

• sapei
• cotton
• hubei province
• irrigation and drainage
• drought
• waterlogging