黄土高原流域洪水要素演化过程及同步性特征——以窟野河为例

Evolution and synchronization characteristics of flood elements in Loess Plateau watershed.Case study of Kuye River

解析黄土高原洪水要素变化及同步性对科学认识黄土高原生态治理水文效应,提升流域防洪减灾水平意义重大。以窟野河流域为研究对象,基于水文过程消退法,识别并解析了年最大洪水事件、特征要素及其非一致性特征;基于构建的洪水特征指标变化范围法,定量评估了不同洪水特征要素的改变强度;基于灰色关联度法,探究了不同洪水特征要素间的同步性特征。结果表明:洪水特征要素表现出显著的下降趋势,且伴随两阶段变异;水土保持、退耕还林还草及采煤开矿等人类活动协同改变着流域洪水事件的强度和特点,总体为中度改变;洪峰、洪量及洪水次数的同步性变化程度一直处于高位,且1999年后有所增强,中小洪水的致灾风险值得关注。

Analyzing the changes and synchronicity in the flood elements of a Loess Plateau watershed is essential for a scientific understanding of the hydrological effects of ecological management in this region,and it is of great significance for improving the level of flood control and disaster reduction.This paper identifies and examines the annual maximum flood events,characteristic elements,and non-consistency characteristics in a river basin based on the hydrograph recession algorithm,through a case study of the Kuye River,a tributary of the Yellow River.We evaluate the changes in intensity of different flood characteristic elements using the constructed range of variability approach for flood characteristic index,and explore synchronization characteristics between these elements using the gray relational degree method.The results show that the flood characteristics take a significant decreasing trend with two-stage variations,and that human activities-such as water and soil conservation measures,land retirement for afforestation and grassland rehabilitation,and coal mining-have synergistically changed the intensity and characteristics of flood events in the basin to a moderate degree.A high degree has remained of the change in the synchronicity of flood peaks,flood volume,and flood frequency;the change rate has grown since 1999.Thus,great attention should be paid to the risk of medium and small floods.