Impact of climatic and geomorphologic drivers on sediment connectivity in the Tarim River Basin, China

• Published in: Journal of hydrology (Amsterdam) 2024-11, Vol.643, p.132027, Article 132027
• Main Authors: Liu, Chuanxiu, Chen, Yaning, Fang, Gonghuan, Li, Zhi, Liu, Yongchang
• Format: Article
• Language: English
• Subjects: Climate change; Geomorphology; Inland river basin; Land restoration; Land-use/land-cover; Sediment connectivity
• ISSN: 0022-1694
• DOI: 10.1016/j.jhydrol.2024.132027

[Display omitted] •Spatially, 31% of Tarim basin (China) showed a decreasing trend in index of connectivity (IC).•The explanatory power of geomorphic factors for IC increases gradually over time.•Natural restoration leads to lower IC reductions than anthropogenic restoration.•Sediment connectivity is an effective indicator to detect land degradation. Sediment connectivity influences sediment flux in the Tarim River Basin (TRB), a region facing severe sedimentation and desertification, which directly threaten the region’s ecological security. To analyze the potential connectivity of sediment from hillslope to catchment outlets, we calculated the index of connectivity (IC) of TRB from 1990 to 2020 using a sediment connectivity model, referencing catchment outlets, and analyzed the impacts of climatic and geomorphic drivers on sediment connectivity. The results showed that the annual average IC ranged from −10.36 to 2.26 during study period. Approximately 30.56 % of the area exhibited a decreasing trend, and 8.57 % showed an increasing trend. The IC was lower in the downstream area (sediment sinks) than in the upstream area (sediment sources). Additionally, the IC increased with elevation and slope. Furthermore, the pattern and rate of land-use transformation had a substantial influence on sediment connectivity. Land restoration (increase in vegetation cover) resulted in a reduction of IC, particularly in the case of anthropogenic land restoration (ΔICmean = -0.09). Conversely, land degradation led to an increase in IC (ΔICmean = 0.04). Attribution analysis indicated that climatic factors had a greater influence on IC than geomorphologic factors, with temperature being the primary driver of IC variation (26.99 %). The explanatory power of geomorphologic drivers (elevation, slope) gradually increased over time. Moreover, a non-linear increase in explanatory power of factor interactions on IC was identified, with clear spatial differentiation characteristics in the interactions. These findings improve our our understanding of the spatial heterogeneity of soil erosion processes in the TRB and provide theoretical support for the implementing soil and water conservation strategies.