Spatiotemporal variation in droughts during winter wheat growing season in the Huaibei Plain

Abstract

【Objective】 The Huaibei Plain in central China is a major agricultural production area where winter wheat often experiences drought during its growing season. This study analyses the spatiotemporal variation in drought during the winter wheat growing season in this region. 【Method】 The analysis was based on meteorological data measured from 1957 to 2018. We used the crop water deficit index (CWDI) during the wheat growing season as a proxy for drought, analysing its inter-annual variation, spatial distribution, fluctuation patterns, occurrence rates, and spatial frequency distribution across different areas in the region. 【Result】 ① Throughout the wheat growing season, ten-day water demand and water supply both showed an initial decrease followed by an increase. Effective precipitation per ten-day period was less than 10 mm, while soil-surface evaporation increased by 260% from mid-March to late May. ② During the growing season, water supply and demand were balanced in Fuyang, Bengbu, and Mengcheng, but not in Dangshan, Bozhou, and Suzhou. Suzhou had the greatest fluctuation in CWDI, while Bengbu had the least. ③ From 1957 to 2018, drought occurrence during the winter wheat growing season increased by approximately 1.5 times, with 2010 experiencing the most widespread and severe droughts. ④ Spatially, drought severity increased from the South to the North, with Dangshan, characterized by fluvo-aquic soil, experiencing more severe droughts than areas with Shajiang Mollisol. Over time, the center with high-frequency of moderate drought shifted northward toward Bozhou and Suzhou. Extreme droughts were rare in this region. 【Conclusion】 Drought severity during the winter wheat growing season in the Huaibei Plain has increased from 1957 to 2018. Water supply and demand are imbalanced in regions such as Dangshan and Suzhou, where supplemental irrigation is needed.

Keywords

• agricultural drought
• winter wheat
• crop water deficit index
• spatiotemporal variation