Variation in the sediment deposition behind check‐dams under different soil erosion conditions on the Loess Plateau, China

Abstract

To maintain a reasonable sediment regulation system in the middle reaches of the Yellow River, it is critical to determine the variation in sediment deposition behind check‐dams for different soil erosion conditions. Sediment samples were collected by using a drilling machine in the Fangta watershed of the loess hilly–gully region and the Manhonggou watershed of the weathered sandstone hilly–gully (pisha) region. On the basis of the check‐dam capacity curves, the soil bulk densities and the couplet thickness in these two small watersheds, the sediment yields were deduced at the watershed scale. The annual average sediment deposition rate in the Manhonggou watershed (702.0 mm/(km2·a)) from 1976 to 2009 was much higher than that in the Fangta watershed (171.6 mm/(km2·a)) from 1975 to 2013. The soil particle size distributions in these two small watersheds were generally centred on the silt and sand fractions, which were 42.4% and 50.7% in the Fangta watershed and 60.6% and 32.9% in the Manhonggou watershed, respectively. The annual sediment deposition yield exhibited a decreasing trend; the transition years were 1991 in the Fangta watershed and 1996 in the Manhonggou watershed (P < 0.05). In contrast, the annual average sediment deposition yield was much higher in the Manhonggou watershed (14011.1 t/(km2·a)) than in the Fangta watershed (3149.6 t/(km2·a)). In addition, the rainfalls that induced sediment deposition at the check‐dams were greater than 30 mm in the Fangta watershed and 20 mm in the Manhonggou watershed. The rainfall was not the main reason for the difference in the sediment yield between the two small watersheds. The conversion of farmland to forestland or grassland was the main reason for the decrease in the soil erosion in the Fangta watershed, while the weathered sandstone and bare land were the main factors driving the high sediment yield in the Manhonggou watershed. Knowledge of the sediment deposition process of check‐dams and the variation in the catchment sediment yield under different soil erosion conditions can serve as a basis for the implementation of improved soil erosion and sediment control strategies, particularly in semi‐arid hilly–gully regions. Copyright © 2018 John Wiley & Sons, Ltd.

Asynchronized erosion effects due to climate and human activities on the central Chinese Loess Plateau during the Anthropocene and its implications for future soil and water management

“…The results were in general agreement with other reported ASSY for the CLP. For example, the mean ASSY was found to be 0.31 × 10 4 t/(km 2 a) during 1975–2013 within the Fangta catchment of the Yanhe watershed near the plateau–gully region (Wei et al, 2018), while a higher mean ASSY of 1.20 × 10 4 t/(km 2 a) was reported for the Nianyegou catchment of the Wudinghe watershed in the northern hilly–gully region during A.D. 1960–1990 (Zhao et al, 2017).…”

“…The couplet specific sediment yield (CSSY) and annual specific sediment yield (ASSY) were calculated based on the methods of Wang et al (2019) and Wei et al (2018), which were the common ways to estimate the sediment yield within the check dams and landslide‐dammed reservoirs on the CLP. Briefly, the CSSY and ASSY in the JB and HS catchments during A.D. 1850–2000 were determined from Equations and , respectively: where S 1 and S 2 are the top and bottom surface areas of each couplet (m 2 ), respectively; H is the thickness of each couplet (m); δ is the bulk density (1.4 t/m 3 as the mean density of representative sediment samples from check dams and landslide‐dammed reservoirs on the CLP; Zhang et al, 2009); A is the catchment area of the reservoir (m 2 ); TE is the trapping efficiency of the landslide dam (assuming 100% TE due to intact dams since the formation of both reservoirs); n is the number of the couplet within an individual year.…”

“…Owing to the short time series of available meteorological data on the CLP, historical precipitation before A.D. 1960 was reconstructed by extrapolation based on a plot of the CSSY versus the corresponding measured precipitation since the 1960s, provided by local meteorological bureaus. This method was recommended as a valid way to rebuild the historical precipitation of individual hydrological events due to one‐to‐one correspondence between the couplet and the hydrological event (Wei et al, 2018; Zhang et al, 2009). Additionally, background climate data during A.D. 1850–2000 included: (1) reconstructed precipitation change in the JB and HS catchments based on tree rings (with a moving average of 11 years) at Mt.…”

Accuracy Assessment of the Planar Morphology of Valley Bank Gullies Extracted with High Resolution Remote Sensing Imagery on the Loess Plateau, China

“…The study area shows a landscape of high-density and deep-cut gullies with a gully density of 3.8 km/km 2 [50], and consequently an extremely broken and undulating topography. Three main gully types exist on the Chinese Loess Plateau: hillslope gully, valley floor gully and valley bank gully [19] (Figure 2).…”

Assessment of soil erosion in the Dongting Lake Basin, China: Patterns, drivers, and implications

“…Yu et al suggested that climate change, especially precipitation, has a strong influence on soil erosion in the Loess Plateau [28]. Wei et al analyzed a small watershed in the Loess Plateau and considered the Grain for Green Project to be the main reason for the decrease in the soil erosion in the Fangta watershed [29]. Although scholars have studied the effects of various factors, including climate, terrain, soil, and vegetation, on soil erosion [30][31][32], few have discussed their different effects on soil erosion depending on the land use type.…”