Soil conservation on the Loess Plateau and the regional effect: impact of the ‘Grain for Green' Project

Author(s):  
Xiaofeng WANG ◽  
Feiyan XIAO ◽  
Xiaoming FENG ◽  
Bojie FU ◽  
Zixiang ZHOU ◽  
...  

ABSTRACTSoil conservation on the Loess Plateau is important not only for local residents but also for reducing sediment downstream in the Yellow River. In this paper, we report a decrease in soil erosion from 2000 to 2010 as a result of the ‘Grain for Green' (GFG) Project. By using the Revised Universal Soil Loss Equation and data on land cover, climate and sediment yield, we found that soil erosion decreased from 6579.55tkm–2yr–1 in 2000 to 1986.66tkm–2yr–1 in 2010. During this period, there was a major land cover change from farmland to grassland in response to the GFG. The area of low vegetation coverage with severe erosion decreased dramatically, whereas the area of high vegetation coverage with slight erosion increased. Our study demonstrates that the reduction in soil erosion on the Loess Plateau contributed to the decrease in the sediment concentration in the Yellow River.

Author(s):  
Xueli Zhang ◽  
Yue Yu ◽  
CaiHong Hu ◽  
Jianhua Ping

Abstract In recent years, the amount of water and sediment in the Yellow River Basin has dropped drastically. This paper selected 125 rainfall and flood data points from 1965 to 2015, combined hydrological methods and mathematical statistics to analyze the hydrological factors and runoff generation mechanism, and combined the underlying surface conditions of the Gushanchuan Basin. The characteristics of change revealed the temporal and spatial variation characteristics and related factors of the runoff generation mechanism in the basin. The results showed that the Gushanchuan Basin is still dominated by HOF runoff, but the runoff generation mechanism also has changed with changes in the underlying surface, which are reflected in increased runoff components, the reduced proportion of HOF runoff, and the increased proportion of saturation-excess overland flow (SOF) runoff and mixed runoff. We analyzed the variation law of underlying surface in the basin, which indicated that the increase in the forest grass area was the main factor affecting changes in the watershed runoff generation mechanism. This research will enable a deeper understanding of the runoff generation mechanism of the main soil erosion areas in the Loess Plateau, reveal variations in the runoff generation mechanism in the Yellow River.


2021 ◽  
Author(s):  
Yongyong Ma ◽  
Zhanbin Li ◽  
Jingming Hou ◽  
Peng Li ◽  
Zongping Ren ◽  
...  

<p>In recent years, the significantly decrease of water and sediment in the Yellow River has attracted wide attention from domestic and foreign scholars. The Loess Plateau is the main source of sediment in the Yellow River, which ecological environment changes caused by large-scale ecological construction measures is considered as one of the main factors affecting the water and sediment changes in the Yellow River. In this study, the Wangmaogou small watershed in Loess Plateau was taken as the study area. On the basis of summing up the process of ecological construction in Wangmaogou watershed, and restoring the topography before ecological construction by topographic map, we set up four scenarios of ecological construction to analyzed the characteristics of sediment connectivity under different ecological construction scenarios and the effects of ecological construction on sediment connectivity, which are before ecological construction, only slope measures are built, only channel measures are constructed, and at the same time slope measures and channel measures are constructed. Under the same ecological construction scenario, the index of sediment connectivity (IC) of the basin shows a decreasing trend from ridge to gully, which mean the connectivity of the sediment at the ridge is less than that at the gully, and the gully are more prone to occur soil erosion than ridge. The distributed of large amount of construction land in the middle and lower reaches at the main gully of Wangmaogou small watershed reduces the connectivity of their surrounding sediment, and the region is prone to occur sediment deposition. Eco-construction measures have decreased significantly the sediment connectivity index (p<0.01) of Wangmaogou small watershed, and reduced the occurrence of soil erosion. Laying ecological measures lessened the possibility of local soil erosion, and increased the resistance of sediment in the transport process. Compared with the situation without ecological control, the mean of D<sub>up</sub> index decreased by 75.27% by laying slope and gully measures, while the mean of D<sub>up</sub> index decreased by only 6.45% by laying gully measures.</p>


Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 529 ◽  
Author(s):  
Chenlu Huang ◽  
Qinke Yang ◽  
Xiayu Cao ◽  
Yuru Li

Soil erosion is a serious environmental problem in the Loess Plateau, China. Therefore, it is important to understand and evaluate soil erosion process in a watershed. In this study, the Chinese Soil Loss Equation (CSLE) is developed to evaluate the soil loss and analyze the impact of land use and slope on soil erosion in Jiuyuangou (JYG) watershed located in the hilly-gullied loess region of China 1970–2015. The results show that the quantities of soil erosion decreased clearly from 1977 to 2015 in the study area, which from 2011 (t/km²·a) in 1977 to 164 (t/km²·a) in 2004 and increased slowly to 320 (t/km²·a) in 2015. No significant soil erosion (<300 t/km²·a) changed in JYG watershed, which increased dramatically from 8.93% to 69.34% during 1977–2015. The area of farmland in this study area has been reduced drastically. Noting that the annual average soil erosion modulus of grassland was also showing a dropped trend from 1977 to 2015. In addition, the study shows that the annual average soil erosion modulus varied with slope gradient and the severe soil erosion often existed in the slope zone above 25°, which accounted for 4657 (t/km²·a) in 1977 and 382.27 (t/km²·a) in 2015. Meanwhile, soil erosion of different land-use types presented the similar changing trend (declined noticeably and then increased slowly) with the change of slope gradient from 1977 to 2015. Combined the investigations of extreme rainfall on 26 July 2015 for JYG watershed, the study provides the scientific support for the implementation of soil and water conservation measures to reduce the soil erosion and simplify Yellow River management procedures.


2020 ◽  
Vol 8 ◽  
Author(s):  
Suzhen Dang ◽  
Xiaoyan Liu ◽  
Huijuan Yin ◽  
Xinwei Guo

The Yellow River is one of the rivers with the largest amount of sediment in the world. The amount of incoming sediment has an important impact on water resources management, sediment regulation schemes, and the construction of water conservancy projects. The Loess Plateau is the main source of sediment in the Yellow River Basin. Floods caused by extreme precipitation are the primary driving forces of soil erosion in the Loess Plateau. In this study, we constructed the extreme precipitation scenarios based on historical extreme precipitation records in the main sediment-yielding area in the middle reaches of the Yellow River. The amount of sediment yield under current land surface conditions was estimated according to the relationship between extreme precipitation and sediment yield observations in the historical period. The results showed that the extreme rainfall scenario of the study area reaches to 159.9 mm, corresponding to a recurrence period of 460 years. The corresponding annual sediment yield under the current land surface condition was range from 0.821 billion tons to 1.899 billion tons, and the median annual sediment yield is 1.355 billion tons, of which more than 91.9% of sediment yields come from the Hekouzhen to Longmen sectionand the Jinghe River basin. Therefore, even though the vegetation of the Loess Plateau has been greatly improved, and a large number of terraces and check dams have been built, the flood control and key project operation of the Yellow River still need to be prepared to deal with the large amount of sediment transport.


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