Step-pool morphology in ephemeral gullies on steep slopes of the Loess Plateau: comparisons with other linear erosion features

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology Pub Date : 2025-09-07 DOI:10.1016/j.geomorph.2025.110007

Wenqian Liang , Ximeng Xu , Fenli Zheng

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引用次数: 0

Abstract

Step-pool morphology has a great impact on hydraulic resistance and energy dissipation, closely associated with channel stability. The occurrence of the maximum flow resistance condition suggests maximum channel stability, which has been widely found in linear erosion features including streams and rills. However, step-pool morphology in ephemeral gullies (EGs) on steep slopes remains unclear, compared with other linear erosion features. Thus, field investigation was conducted in the two EGs on steep slopes of the Chinese Loess Plateau. The H/L and (H/L)/S of 171 step-pools in the two EGs (64 % and 58 % slope gradients) were analyzed and compared with eight sets of literature data in other linear erosion features, where H, L, and S represent step height, step spacing, and channel slope gradient, respectively. The results demonstrated that the step-pool morphology in EG channels of the study area was controlled by S. Steeper channel slope led to larger step-pool instability. H/L increased with the S, ranging from 0.11 to 1.00. In the two EGs, the maximum flow resistance condition occurred in half of step-pools with (H/L)/S ranging from 1 to 2, while another half of step-pools had (H/L)/S below 1, indicating fewer stable arrangements, and were predominantly found at S larger than 0.4. By incorporating monitored data from EGs and literature data from other linear erosion features, the relationship between step-pool morphology and channel slope gradient was also identified. H/L increased linearly with S, while (H/L)/S decreased as S increased, following a power function. When S was between 0.068 and 0.448, the (H/L)/S fell into the range of 1 to 2, representing the occurrence of the maximum flow resistance condition. This study fills a gap in understanding step-pool morphology in EGs on steep slopes by comparing with other linear erosion features and underscores the critical role of channel slope gradient.

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黄土高原陡坡上短暂性沟壑的阶梯池形态：与其他线性侵蚀特征的比较

台阶池形态对水阻力和能量耗散有很大影响，与通道稳定性密切相关。最大流阻条件的出现表明通道的最大稳定性，这在包括溪流和细沟在内的线性侵蚀特征中广泛存在。然而，与其他线性侵蚀特征相比，陡坡上的瞬时沟（EGs）的阶梯池形态尚不清楚。为此，对中国黄土高原陡坡上的两个试验区进行了野外调查。分析了2个EGs（坡度为64%和58%）171个台阶池的H/L和(H/L)/S，并与其他8组线性侵蚀特征的文献数据进行了比较，其中H、L和S分别代表台阶高度、台阶间距和河道坡度。结果表明，研究区EG河道的台阶池形态受s控制，河道坡度越大，台阶池不稳定性越大。H/L随S增大而增大，范围为0.11 ~ 1.00。在两个EGs中，最大流动阻力出现在一半的阶梯池中，(H/L)/S在1 ~ 2之间，而另一半的阶梯池(H/L)/S在1以下，表明稳定排列较少，且主要出现在S大于0.4的位置。通过结合EGs的监测数据和其他线性侵蚀特征的文献数据，还确定了台阶池形态与河道坡度之间的关系。H/L随S的增加呈线性增加，(H/L)/S随S的增加呈幂函数递减。当S在0.068 ~ 0.448之间时，(H/L)/S在1 ~ 2之间，表示出现了最大流阻状态。该研究通过与其他线性侵蚀特征的比较，填补了对陡坡上斜坡侵蚀的阶梯池形态的认识空白，并强调了河道坡度的关键作用。

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来源期刊

Geomorphology 地学-地球科学综合

CiteScore

8.00

自引率

10.30%

发文量

309

审稿时长

3.4 months

期刊介绍： Our journal''s scope includes geomorphic themes of: tectonics and regional structure; glacial processes and landforms; fluvial sequences, Quaternary environmental change and dating; fluvial processes and landforms; mass movement, slopes and periglacial processes; hillslopes and soil erosion; weathering, karst and soils; aeolian processes and landforms, coastal dunes and arid environments; coastal and marine processes, estuaries and lakes; modelling, theoretical and quantitative geomorphology; DEM, GIS and remote sensing methods and applications; hazards, applied and planetary geomorphology; and volcanics.