Prevalent sediment source shift after revegetation in the Loess Plateau of China: Implications from sediment fingerprinting in a small catchment

Abstract

As an important soil and water conversation endeavor, the 'Grain for Green' project launched by the Chinese Central Government almost doubled the vegetation cover on the Loess Plateau between 1999 and 2013. The corresponding vegetation restoration considerably diminished slope erosion throughout the Loess Plateau, although erosion in gullies remains poorly understood. In this paper, a composite fingerprinting approach was employed to assess the relative importance of the erosion of gully and slope soils within a typical dam-controlled catchment of the Loess Plateau. A total of 23 couplets were identified based on the deposited layer thicknesses and extreme rainfall event records along the sediment profile. The results suggest that gullies contributed 71% to the overall sediment proportion, and those sediments had an increased tendency to accumulate during 2010-2016 under the 'Grain for Green' project. The sediment inputs from slope areas were predicted to be 29%. The eroded gullies materials mainly consisted of silt-sized particles, which dominated the eroded sediment. Silt particles with sizes of 0.02-0.05 mm constituted the main particles in both deposit sediments and gully materials, whereas the slope areas mainly contained particle sizes of <0.01 mm. The check dam proved to be effective at trapping coarse silt with 27-42% of the total sediment content. This study presents reliable information on the importance of gullies as sediment source materials and verifies the applicability of tracing procedures for collecting information on sediment effluxes from both slopes and gullies.

Quantifying the efficiency of soil conservation and optimized strategies: A case‐study in a hotspot of afforestation in the Loess Plateau

“…Soil erosion in the Loess Plateau not only caused agricultural degradation and farmers' poverty, but also threatened the ecological security of the Yellow River Basin (Heerink, Bao, Li, Lu, & Feng, 2009; Jiao, Wang, Zhao, Wang, & Mu, 2014; Li et al, 2012; Sun et al, 2014). In the Loess Plateau, the goal of the GFG is to prevent the severe soil erosion and reduce the sediment content in the Yellow River (Wang, Fang, Shi, & Lu, 2018; Zhou, Gan, Shangguan, & Dong, 2009). The GFG has had positive and far‐reaching effects on the ecological environment and economic development in relevant regions over the past 20 years (Gao, Liu, Li, & Shi, 2020; Jia et al, 2014).…”

Soil Organic Carbon Redistribution and Delivery by Soil Erosion in a Small Catchment of the Yellow River Basin

“…The goodness of fit (GOF) can be used to verify whether the output of the mixing model is acceptable (Wang, Fang et al, 2018). Motha et al (2003) indicated that the output could be accepted when GOF > 80.0%.…”

Fingerprinting sub-basin spatial sediment sources in a large Iranian catchment under dry-land cultivation and rangeland farming: Combining geochemical tracers and weathering indices

“…Accelerated soil erosion is a serious environmental problem (Wang et al, 2018) affecting the physical, chemical and biological quality of land and water worldwide (Malhotra et al, 2018). Although fine-grained sediment is a naturally occurring material in river systems, providing a fundamental input for the development of river landscapes and their aquatic ecosystems (Frostick et al, 1984; Lisle, 1989), excessive fine-grained sediment delivery to, and accumulation within, river systems is one of the most pervasive causes of watercourse degradation worldwide (Gellis and Gorman Sanisaca, 2018).…”

“…Although fine-grained sediment is a naturally occurring material in river systems, providing a fundamental input for the development of river landscapes and their aquatic ecosystems (Frostick et al, 1984; Lisle, 1989), excessive fine-grained sediment delivery to, and accumulation within, river systems is one of the most pervasive causes of watercourse degradation worldwide (Gellis and Gorman Sanisaca, 2018). In fact, since the 1980′s there has been growing concern in many countries over the off-site issues associated with accelerated soil erosion (Evans et al, 2017), including muddy floods and the related damage to properties (Boardman et al, 1996), increased operational and maintenance costs for potable water purification (Cashman et al, 2018; Owens et al, 2016), deformation of channel morphology (Cashman et al, 2018; Collins and Walling, 2007; Gellis and Gorman Sanisaca, 2018; Haddadchi et al, 2013; Zhou et al, 2016), the excessive destruction of the earth (Wang et al, 2018), the transfer and redistribution of nutrients and pollutants (Blake et al, 2018; Carter et al, 2003; Collins and Walling, 2007; Westrich and Förstner, 2007), and the harmful effects on aquatic biology (Jones et al, 2014, 2012; Kemp et al, 2011; Wilkes et al, 2019). Alongside these off-site impacts, a wide range of on-site problems also result from accelerated soil erosion and sediment mobilization including, amongst others, reductions in soil fertility and water holding capacity and reduced crop productivity (Nosrati, 2017; Tiecher et al, 2018).…”

“…Improved understanding of sediment sources can be utilized as an important basis for the conceptualization and confirmation of the drivers (e.g. modern intensive farming) of accelerated soil erosion and sediment transport (Gellis and Gorman Sanisaca, 2018; Walling et al, 1993; Wang et al, 2018; Zhou et al, 2016), and to help target management (Laceby et al, 2017; Walling, 2005). To this end, uptake and refinement of sediment source tracing or fingerprinting techniques has expanded dramatically as an alternative approach to traditional methods of identifying key sediment sources (Blake et al, 2018; Carter et al, 2003; Collins et al, 1998, 2017b; Collins and Walling, 2007; Walling et al, 1993, 1999) and erosion processes in many environmental settings (Collins et al, 2010, 2017a; Froger et al, 2018; Haddadchi et al, 2013; Koiter et al, 2013).…”