Abstract:

Shuozhou City, located in the semi-arid and ecologically fragile region of northern Shanxi, is highly sensitive to precipitation changes due to its rain-fed agricultural system. Climate change has intensified spatiotemporal fluctuations in precipitation and increased the frequency of droughts and floods, severely affecting agricultural stability. This study aims to reveal the spatiotemporal patterns of precipitation evolution and their dual impacts on agriculture, providing scientific support for optimizing local agricultural planning and disaster risk prevention and management capabilities. Based on precipitation data of 54 years (1972-2025) from six counties and districts in Shuozhou, we applied linear trend estimation, the Mann-Kendall test, and Morlet wavelet analysis to examine precipitation trends and their effects on agriculture. Results showed that the annual precipitation in Shuozhou decreased gradually from west to east, with higher values in the western regions. Both annual and daily maximum precipitations showed increasing trends, rising by 18.0 mm per decade and 1.5 mm per decade, respectively. Precipitation during spring, summer, and autumn had all increased significantly, while winter precipitation showed no notable change. Since 1991, precipitation had steadily increased across decades, with the most pronounced growth occurring between 2016 and 2025; average precipitation over the past 30 years had been significantly higher than in earlier periods. Precipitation was concentrated from May to September, accounting for 70% of the annual total, with July and August alone contributing 48%. Extreme precipitation events peaked from late July to mid-August, with a record high of 117.1 mm recorded in Shuocheng District. Annual precipitation showed a sudden shift in 2023 and exhibited a 3-year cycle, while daily extreme precipitation experienced two abrupt shifts (in 1979 and 2001) and followed a 2-5 year cycle. The impact of precipitation changes on agriculture is mixed: increased rainfall helps alleviate spring and summer droughts, improves soil moisture, and promotes higher yields of drought-tolerant crops. However, more frequent short-term heavy rains in summer and prolonged rainy spells in autumn increase risks of flooding, water logging, crop lodging, and disease outbreaks. Uneven spatial distribution further intensifies regional disparities in agricultural vulnerability. Overall, over the past 54 years, Shuozhou has experienced an upward trend in precipitation, with greater concentration and increased extremity. While this generally benefits dry land farming, seasonal imbalance and frequent extreme events threaten production stability. Future strategies should account for regional differences-improving drainage and flood prevention in eastern areas and promoting rainwater harvesting and supplementary irrigation in western areas, while optimizing crop varieties and sowing schedules to achieve efficient water use and effective disaster mitigation. This research provides a scientific basis for climate resource utilization and agricultural planning in the region.

Key words: Shuozhou City, spatial-temporal variation of precipitation, linear trend estimation, Mann-Kendall test, impact on agricultural