Characteristics of temporal and spatial distribution changes of extreme rainfall in different geomorphic types in Shanxi Province

Abstract

[Objective] Investigating extreme rainfall patterns in the context of global climate change can aid in ecological protection, climate change response, water resource management, and environmental impact assessment. [Methods] Utilizing daily precipitation data from 27 meteorological stations in Shanxi Province from 1975 to 2020, extreme precipitation events over a span of 46 years were selected. Ten extreme precipitation indices recommended by ETCCDMI were calculated. Eleven characteristic indicators, including significance level(P_value), trend Slope(Slope), Mean value(Mean_value), and Median value(Median_value), were used to analyze the trends and distribution of the data. The corresponding extreme precipitation index characteristics were calculated by superimposing landform types, analyzing the intensity, distribution, and trend changes of extreme rainfall events across different landform types, exploring the correlation between extreme rainfall and landform types, and revealing the distribution characteristics of extreme rainfall in various landform types. [Results] All sites in Shanxi Province showed a decreasing trend in CDD, with 81% of the sites reaching significance. Except for CWD, the other eight extreme precipitation indices had more sites with positive correlations, with the proportions of sites positively correlated with PRCPTOT, R10mm, Rx1day, and Rx5day reaching 74%, 74%, 69%, and 67%, respectively, although the overall significance was low. The spatial distribution of CDD in Shanxi Province exhibited an increasing trend of reduction from south to north and west to east. Six indices, including the Mean value of CDD, showed similar spatial distribution characteristics, gradually decreasing in a gradient from north to south. Three indices, including CV, shared similar spatial distribution characteristics, with a radiating decrease from north to south at the junction of Yangquan and Xinzhou in the southeast. The drought situation in the northern part of Shanxi Province alleviated faster than in the southern part. There was a significant correlation between elevation in Shanxi Province and the indices CDD, CWD, PRCPTOT, R10mm, and Rx5day. CDDSlope, the Median of CWD, Ave_Year_Change, Q50 value, and the Minimum value of Rx5day all showed significant negative correlations(-0.44,-0.41,-0.42,-0.41,-0.45), while the Slope values of PRCPTOT and R10mm showed significant positive correlations(0.46, 0.45). All six indicators of SDII showed significant negative correlations, indicating a significant overall impact on SDII. [Conclusion] The relief amplitude of Shanxi Province had no significant correlation with the characteristic values of extreme climate indices. The distribution characteristics of extreme precipitation index characteristic indicators varied across different landform types in Shanxi Province. Indicators were more scattered in low-altitude hilly terraces, small undulating middle mountains, and mid-altitude hilly terraces, requiring consideration of spatial variation within these landform types regarding extreme climate indices.

Keywords

extreme rainfall / characteristic index / geomorphic type / Shanxi Province / climate change / ecological protection / water resources / rainfall