中小河流径流变化及其对降水的响应：以千河为例

Runoff variations in small and medium-sized rivers and their response to precipitation: A case study of Qian River

摘要

【目的】为了进一步探究中小河流极端径流与流域降水变化的关系，提高洪涝灾害预警的精确性，【方法】以黄河流域渭河水系的千河为半干旱地区中小河流的代表，充分利用千河流域2010—2021年流量和小时降水量观测数据，基于均值标准差分级法和Topsis熵权法，分析流域流量的多时空尺度变化，并聚焦4次极端径流过程，探讨径流对流域降水响应的敏感性和滞后性。【结果】结果如下：(1)千河流域的流量年际波动较大，呈先减后增的趋势，季节分配极不均匀，峰值通常出现在7月，并且流量以枯和偏枯状态为主。(2)基于4次极端径流过程，发现其流量大、来势凶猛、洪峰历时长，且以单峰型为主，另有复峰型。(3)影响千河极端径流的流域降水分布不均，强降水中心集中在上游陇县和千阳的交界处，表现为突发性大暴雨天气，如22个站中有14个站达到短时强降水量级，其中有2个站达到50 mm/h以上。此外连续的降水天气，即使降水强度小，累积降水量也能导致极端径流过程。(4)极端径流变化对各站降水量响应的敏感性和时间滞后性不同，14个关键站点对径流贡献显著，其中东南、杜阳、陇县和温水站的降水量分别在3 h、9 h、15 h和19 h后开始稳定影响到流量变化。【结论】本研究揭示了极端径流过程中流量对流域降水的响应关系，能够为科学合理地开发和利用水资源以及治理洪涝灾害提供决策支持。

Abstract

[Objective] To further explore the relationship between extreme runoff and river basin precipitation variations in small and medium-sized rivers, and to improve the accuracy of flood disaster warning. [Methods] Taking the Qian River, a representative small and medium-sized river in the semi-arid regions of the Weihe River system in the Yellow River Basin, as an example, the flow and hourly precipitation data from 2010 to 2021 in the Qian River Basin were utilized. Based on the mean standard deviation classification method and the Topsis entropy weight method, the spatiotemporal variations in the river flow were analyzed. Focusing on four extreme runoff events, the sensitivity and lag in the runoff's response to river basin precipitation were investigated. [Results] The result were as follows:(1) the flow in the Qian River Basin exhibited significant interannual variability, showing a trend of first decreasing and then increasing. Seasonal distribution was extremely uneven, with peak flow typically occurring in July, and the flow was mainly in dry or slightly dry states.(2) Based on four extreme runoff events, it was found that the flow was high, with a rapid onset and long flood peak duration. The runoff predominantly exhibited a unimodal pattern, although bimodal occurrences were also observed.(3) The distribution of river basin precipitation affecting extreme runoff in the Qian River was uneven, with strong precipitation concentrated in the upstream area at the junction of Longxian and Qianyang. This was characterized by sudden heavy rainfall, with 14 out of 22 stations reaching the short-duration heavy rainfall level, including two stations with precipitation exceeding 50 mm/h. In addition, continuous rainfall, even at low intensity, could lead to extreme runoff events due to cumulative precipitation.(4) The sensitivity and time lag of runoff responses to precipitation varied across stations. At 14 key stations, significant contributions to runoff were observed, with precipitation at Dongnan, Duyang, Longxian, and Wenshui stations stabilizing the flow variations after 3, 9, 15, and 19 hours, respectively. [Conclusion] The response relationship between runoff and river basin precipitation during extreme runoff events is revealed, which can provide decision-making support for the scientific and rational development and utilization of water resources, as well as flood and waterlogging disaster management.

关键词

流量 / 中小河流 / 丰枯状态 / 降水量 / 响应滞后性 / 影响因素

Key words

flow / small and medium-sized rivers / wet and dry states / precipitation / response lag / influencing factors

基金资助

陕西省重点研发计划(2023-YBSF-191)

国家自然科学基金项目(U2242202)

中国气象局兰州干旱气象研究所基金(IAM202103)