Emergent stationarity in Yellow River sediment transport and the underlying shift of dominance: from streamflow to vegetation

Abstract

Abstract. Soil erosion and sediment transport play important roles in terrestrial landscape evolution and biogeochemical cycles of nutrients and contaminants. Although discharge is considered to be a controlling factor in sediment transport, its correlation with sediment concentration varies across the Yellow River basin (YRB) and is not fully understood. This paper provides analysis from gauges across the YRB covering a range of climates, topographic characteristics, and degrees of human intervention. Our results show that discharge control on sediment transport is dampened at gauges with large mean annual discharge, where sediment concentration becomes more and more stable. This emergent stationarity can be attributed to vegetation resistance. Our analysis shows that sediment concentration follows a bell shape with vegetation index (normalized difference vegetation index, NDVI) at an annual scale despite heterogeneity in climate and landscape. We obtain the counterintuitive result that, as mean annual discharge increases, the dominant control on sediment transport shifts from streamflow erosion to vegetation retardation in the YRB.

Coupling Effects of Precipitation and Vegetation on Sediment Yield from the Perspective of Spatiotemporal Heterogeneity across the Qingshui River Basin of the Upper Yellow River, China

“…The nonlinear effect of vegetation in terms of sediment resistance to erosion follows that of the previous literature [51,52]. Vegetation is undeniably an important determinant of sediment reduction and could be considered as a useful indicator of both soil erosion and the transport of sediment in the QRB, despite the fact that the possible contribution of additional factors is not accounted for here.…”

“…These conditions contrast with the QRB, with an arid and semi-arid climate and relatively poor vegetation coverage. Despite this difference, a similar bell-shaped relationship was also discovered among precipitation, vegetation, and sediment yield in the QRB, the LP [51], and the YR [52]. This suggests that the bell relationship among these variables does not only occur in humid and well-vegetated regions but can also be applicable in arid and poorly-vegetated areas.…”

“…Xin et al [51] demonstrated that the coupling relationship between vegetation coverage and precipitation was similar to the Langbein-Schumm law based on data from 180 gauging stations around the LP, with vegetation coverage becoming a dominant controlling factor for annual precipitation exceeding 460 mm and an NDVI > 0.4. Ye et al [52] argued that discharge governs the soil erosion and sediment delivery until the NDVI exceeds a threshold of 0.36, at which the driving factor dominating the sediment concentration shifts from precipitation erosion to vegetation retardation, and attributed this to the slow growth of vegetation with increasing resistance to low-level precipitation. Ran et al [7] analyzed flooding and sediment yield at the event scale, particularly on the complexity induced by the non-linearity of sediment delivery, and observed a bell-shaped trend similar to the relationship reported by Langbein-Schumm.…”

Ranking of Basin-Scale Factors Affecting Metal Concentrations in River Sediment

“…Reservoirs play a vital role in the sediment movement in rivers [46,61,62], and larger reservoirs may have a more substantial effect on the transport processes than smaller ones. Many studies have found a connection between vegetation indices such as NDVI and EVI and catchment sediment discharge [63,64]. We found that the importance of NDVI and EVI was generally higher than that of specific land cover types.…”

Revegetation impacts on runoff generation processes in a typical loess catchment

“…Given the thick loess layers, deep groundwater table, and short‐duration heavy rainfall events, infiltration‐excess overland flow was considered as the dominant runoff generation mechanism in the Loess Plateau (Liu et al, 2012). With the recovery of vegetation in the Loess Plateau, studies showed that the runoff coefficient decreased with the elevation of vegetation coverage (Liu et al, 2014; Qiu et al, 2017; Ye et al, 2019). It has been proved that large‐scale ecological restoration accounted a relatively significant proportion for the streamflow reduction (Liang et al, 2015; Sun et al, 2020).…”