How do climate, geomorphology, and land-use control sediment yield generation in an anthropogenically modified landscape?

Sumit Das , Soumi Talukdar, Gianvito Scaringi 

Understanding the controls on sediment yield (SY) is essential for water resource management. However, in the Cauvery basin in India, progress is hindered by fragmented studies that lack an integrated analysis. This research quantifies sub-catchment SY using long-term gauging data and employs Partial Least Squares Regression (PLSR) and multiple regression (MLR) to evaluate geomorphic, climatic, and land-use predictors across 14 representative sub-catchments. Results indicate that geomorphic parameters dominate variation in SY with low hypsometric integral (mean HI = 0.22 ± 0.10), and localised high plan and profile curvature (> 0.01), signifying a mature landscape prone to high sediment export. SY exhibits a strong inverse relationship with the basin area, which reflects significant sediment storage or trapping (dilution effect). Rainfall is the primary climatic driver, while temperature shows no significant link. Land-use effects are secondary and context-dependent, as forests in high-elevation and high-rainfall areas fail to suppress erosion. Crucially, dam infrastructure overrides natural controls by decoupling hillslope erosion from downstream delivery. In fact, the reservoir area alone explains 41% of the SY variability. This study establishes a clear hierarchical relation among the environmental parameters, which is essential for adaptive sediment management, especially targeting headwater erosion hotspots and incorporating sediment continuity into reservoir operations to mitigate downstream impacts.