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北方土石山区典型流域不同类型洪水的水沙关系差异及归因

Differences in Water and Sediment Relationship between Different Types of Floods in Typical Watersheds of Northern Earth and Rocky Mountainous Areas and their Attribution

  • 摘要: 基于水文站的降水、径流和泥沙数据,采用聚类分析、含沙量-流量(SSC-Q)滞回曲线等方法,从事件尺度研究北方土石山区弥河流域不同类型洪水事件的径流、输沙特征,揭示各类洪水水沙关系及输沙贡献情况及水土保持措施影响机制。结果表明:(1)弥河流域1951-2021年的261次洪水事件可划分为小型、中型、大型和特大型四类,洪水事件的滞回曲线类型主要为8字形。随着洪水量级的增加,洪水事件的洪水历时和径流输沙量均呈增长趋势,径流和泥沙变率增加,复合型滞回曲线的占比逐渐加大。(2)大型与特大型洪水事件发生频次最低,但输沙贡献率高达86.9%,是北方土石山区输沙的主要洪水类型,主导弥河流域的水土流失灾害,在流域治理中需重点关注。(3)水土保持措施和人类活动对中、小型洪水事件的影响较大,其水沙关系变率超过10%;但对大型洪水事件的影响相对较小,水沙关系变率仅为1.2%。通过合理配置流域中的水土保持措施,当地中小型洪水事件的水沙关系可得到调节,从而达到拦蓄洪水、调控泥沙的目的。同时,亟需持续加强特大暴雨的水土流失及洪水防控措施,避免其给北方土石山区的生态环境等造成严重破坏。研究结果可为该区域水土保持工作的开展及特大暴雨洪水事件的应对提供理论和实践依据。

     

    Abstract: Based on the precipitation, runoff and sediment data from the hydrological station, cluster analysis and sediment content-flow(SSC-Q) hysteresis curve are used to study the runoff and sand transport characteristics of different types of flood events in the Mihe River Basin of the northern earth and rock mountainous areas from the event scale, and reveal the relationship between various floods and sediments, the contribution of sand transport and the influence mechanism of soil and water conservation measures. The results show that(1) The 261 flood events in the Mihe River Basin from 1951 to 2021 could be divided into four categories: small, medium, large and extra-large, and the flood hysteresis curve type was mainly figure-8. With the increase in flood magnitude, the flood duration and runoff sand transport of flood events showed an increasing trend, the runoff, and sediment variability increased, and the proportion of the composite hysteresis curve gradually increased.(2) The frequency of large-scale and extra-large flood events was the lowest, but the contribution rate of sand transport was as high as 86.9%, which was the main type of flood in the northern earth-rock mountainous area, and dominated the soil erosion disaster in the Mihe River Basin, which needs to be paid attention to in the governance of the river basin.(3) Water and soil conservation measures and human activities have a greater impact on medium and small flood events, and the variability of the water-sediment relationship exceeds 10%. However, the impact on large-scale flood events is relatively small, and the variability of water-sediment relationship is only 1.2%.Through the rational allocation of water and soil conservation measures in the river basin, the relationship between water and sediment in local small and medium-sized flood events can be adjusted, so as to achieve the purpose of flood storage and sediment control. At the same time, it is urgent to continue to strengthen soil erosion and flood prevention and control measures for exceptionally heavy rainfall to avoid serious damage to the ecological environment of the northern earthy mountainous areas. The research findings serve as a theoretical and practical basis for the development of soil and water conservation in the region and the response to exceptionally heavy rainstorms and flood events.

     

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