洮儿河流域极端降水特征与典型雨型分类研究OA

Against the backdrop of global warming,extreme precipitation events are occurring with increasing frequency.This poses severe challenges to the management of water resources in watersheds and to disaster prevention and control.This study focuses on the Tao'er River Basin,conducting a systematic,event-based analysis of extreme precipitation using hourly observational data from regional meteorological stations during the flood seasons(May-September)from 1993 to 2024.Independent rainfall episodes were used to identify extreme precipitation events by combining minimum inter-event time intervals and a percentile-based threshold method.This approach provides a clear physical basis for defining extreme precipitation thresholds and yielded 1 326 independent extreme events.Dimensionless cumulative rainfall curves were then constructed for individual events and K-means clustering was applied to classify the temporal structures of precipitation.This initially produced ten objective clusters.These clusters were then consolidated into four typical rainfall patterns—early-peak,mid-peak,late-peak,and uniform—according to the primary concentration stage of rainfall within the event duration.Characteristic parameters,including total precipitation,duration,average intensity,maximum intensity,peak time coefficient and rainfall centroid coefficient,were employed to characterise each rainfall pattern systematically and quantify its intensity,persistence and precipitation concentration features.Trend tests and linear regression were then used to examine the variations in occurrence frequency of the different rainfall patterns over time,and their contribution to total flood-season precipitation.The results indicate that extreme precipitation in the Tao'er River Basin is primarily concentrated between June and August,with July contributing most significantly,while the early and late flood seasons contribute relatively less.The contribution of extreme precipitation to total flood-season rainfall shows an increasing trend,with a pronounced rise after 2009.This suggests a gradual shift towards extreme rainfall dominating the basin's precipitation structure.The four rainfall patterns differ significantly in terms of duration,rainfall concentration,position and intensity evolution.Early-peak events are characterised by short duration and highly concentrated intensity,reflecting abruptness.Mid-peak events display relatively balanced temporal distributions.Late-peak events exhibit a clear lag in rainfall concentration.Uniform events are associated with longer durations and more evenly distributed rainfall.Early-peak and mid-peak events dominated throughout the study period,with early-peak events demonstrating a statistically significant increasing trend.This study systematically reveals the temporal structural characteristics of extreme precipitation in the Tao'er River Basin,providing a sound physical foundation for identifying extreme events,constructing typical rainfall patterns,and assessing basin-scale flood risk.The findings offer valuable scientific support for optimising flood control operations and enhancing regional water resources management in the context of ongoing climate change.