scholarly journals Effects of Rainfall Intensity and Vegetation Cover on Erosion Characteristics of a Soil Containing Rock Fragments Slope

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Bingqin Zhao ◽  
Lun Zhang ◽  
Zhenyao Xia ◽  
Wennian Xu ◽  
Lu Xia ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Vegetation Cover ◽  
Three Gorges Reservoir ◽  
Rainfall Intensity ◽  
Sediment Load ◽  
Cynodon Dactylon ◽  
Three Gorges ◽  
Rock Fragments ◽  
Runoff Volume ◽  
The Three Gorges

Rainfall events coupled with shallow and gravelly sloping farmland have led to serious soil erosion and associated problems in the Three Gorges reservoir. Previous studies have shown that the use of vegetation is an effective way to control soil erosion. Therefore, an artificial, simulated rainfall experiment study is conducted to determine the effect of rainfall intensity and vegetation cover on runoff volume, sediment load, and runoff hydraulics characteristics. The experiment consists of seven vegetation treatments subjected to three rainfall intensities on a soil that contains rock fragments on a slope of 30°. The results indicate that the runoff volume and sediment load of the bare plot were greater than those of vegetation-covered plots under three different rainfall intensities. When Cynodon dactylon and Indigofera amblyantha were applied together, the plot displayed the best performance for soil loss control, with a reduction of 87.88%–99.11%. According to a redundancy analysis, the change in rainfall intensity had the least impact on the Reynolds number and the runoff volume of the herb-shrub mixed plot in this study. These findings suggest that the effect of combining Cynodon dactylon and Indigofera amblyantha and increasing the vegetation coverage is an effective solution for soil and water loss conservation. The application of this method can alleviate environmental stress on the Three Gorges reservoir.

scholarly journals Mechanized and Optimized Configuration Pattern of Crop-Mulberry Systems for Controlling Agricultural Non-Point Source Pollution on Sloping Farmland in the Three Gorges Reservoir Area, China

2020 ◽  
Vol 17 (10) ◽  
pp. 3599
Author(s):  
Shouqin Zhong ◽  
Zhen Han ◽  
Jiangwen Li ◽  
Deti Xie ◽  
Qingyuan Yang ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Three Gorges Reservoir ◽  
Three Gorges Reservoir Area ◽  
Three Gorges ◽  
Point Source Pollution ◽  
The Three Gorges ◽  
Contour Hedgerow ◽  
Sloping Farmland ◽  
Contour Hedgerows ◽  
Non Point Source Pollution

High-intensity utilization of sloping farmland causes serious soil erosion and agricultural non-point source pollution (AGNSP) in the Three Gorges Reservoir Area (TGRA). Crop-mulberry systems are important agroforestry systems for controlling soil, water, and nutrient losses. However, there are many different mulberry hedgerow planting patterns in the TGRA. In this study, soil structure, nutrient buildup, and runoff nutrient loss were observed in field runoff plots with five configurations: P1 (two longitudinal mulberry hedgerows), P2 (two mulberry contour hedgerows), P3 (three mulberry contour hedgerows), P4 (mulberry hedgerow border), and P5 (mulberry hedgerow border and one mulberry contour hedgerow), as well as a control (CT; no mulberry hedgerows). P1 had the smallest percentage of aggregate destruction (18.8%) and largest mean weight diameter (4.48 mm). P5 led to the greatest accumulation of ammonium nitrogen (NH4+–N) and total phosphorus (TP) (13.4 kg ha−1 and 1444.5 kg ha−1 on average, respectively), while P4 led to the greatest accumulation of available phosphorus (AP), nitrate nitrogen (NO3−–N), and total nitrogen (TN) (114.0, 14.9, and 1694.1 kg ha−1, respectively). P5 was best at preventing soil erosion, with the smallest average annual runoff and sediment loss of 112.2 m3 ha−1 and 0.06 t ha−1, respectively, which were over 72.4% and 87.4% lower than those in CT, respectively. P5 and P4 intercepted the most N in runoff, with average NH4+–N, NO3−–N, particulate N, and TN losses of approximately 0.09, 0.07, 0.41, and 0.58 kg ha−1, respectively, which were 49.7%, 76.2%, 71.3%, and 69.9% lower than those in CT, respectively. P5 intercepted the most P in runoff, with average TP and total dissolved phosphorus (TDP) losses of 0.09 and 0.04 kg ha−1, respectively, which were 77.5% and 70.4% lower than those in CT, respectively. Therefore, the pattern with one mulberry hedgerow border and one mulberry contour hedgerow (P5) best controlled AGNSP, followed by that with only a mulberry hedgerow border (P4).

scholarly journals The Implication of Land-Use/Land-Cover Change for the Declining Soil Erosion Risk in the Three Gorges Reservoir Region, China

2019 ◽  
Vol 16 (10) ◽  
pp. 1856 ◽  
Author(s):  
Jinzhu Jiu ◽  
Hongjuan Wu ◽  
Sen Li
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Land Cover Change ◽  
Natural Resource Management ◽  
Natural Resource ◽  
Three Gorges Reservoir ◽  
Three Gorges ◽  
Erosion Risk ◽  
Soil Erosion Risk ◽  
The Three Gorges

The Three Gorges Reservoir Region (TGRR) in China is an ecologically and politically important region experiencing rapid land use/cover changes and prone to many environment hazards related to soil erosion. In the present study, we: (1) estimated recent changes in the risk pattern of soil erosion in the TGRR, (2) analysed how the changes in soil erosion risks could be associated with land use and land cover change, and (3) examined whether the interactions between urbanisation and natural resource management practices may exert impacts on the risks. Our results indicated a declining trend of soil erosion risk from 14.7 × 106 t in 2000 to 1.10 × 106 t in 2015, with the most risky areas being in the central and north TGRR. Increase in the water surface of the Yangtze River (by 61.8%, as a consequence of water level rise following the construction of the Three Gorges Dam), was found to be negatively associated with soil erosion risk. Afforestation (with measured increase in forest extent by 690 km2 and improvement of NDVI by 8.2%) in the TGRR was associated with positive soil erosion risk mitigation. An interaction between urbanisation (urban extant increased by 300 km2) and vegetation diversification (decreased by 0.01) was identified, through which the effect of vegetation diversification on soil erosion risk was negative in areas having lower urbanisation rates only. Our results highlight the importance of prioritising cross-sectoral policies on soil conservation to balance the trade-offs between urbanisation and natural resource management.

scholarly journals Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

2016 ◽  
Vol 64 (3) ◽  
pp. 237-245 ◽  
Author(s):  
Feng Qian ◽  
Dongbin Cheng ◽  
Wenfeng Ding ◽  
Jiesheng Huang ◽  
Jingjun Liu
Keyword(s):  
Soil Erosion ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Purple Soil ◽  
Three Gorges ◽  
Slope Gradient ◽  
Stream Power ◽  
Yield Rate ◽  
The Three Gorges ◽  
Subsurface Runoff

Abstract Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20°) were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min-1). The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w), stream power was the best predictor of sediment yield rate (R2 = 0.884). Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R2 = 0.897). The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

Vertical variation of soil erosion resistance in the water-level fluctuation zone of the Three Gorges Reservoir, China

2020 ◽  
Author(s):  
Hai Xiao
Keyword(s):  
Soil Erosion ◽  
Three Gorges Reservoir ◽  
Erosion Resistance ◽  
Three Gorges ◽  
Stream Power ◽  
Vertical Variation ◽  
The Three Gorges ◽  
Unit Energy ◽  
Water Level Fluctuation Zone ◽  
Soil And Water

<p>The operation of the Three Gorges Reservoir (TGR) altered the distribution of the soil properties, the plant community composition and biomass in the water-level fluctuation zone (WLFZ). However, the vertical variation of soil erosion resistance in the WLFZ of the TGR is still unclear and need to be further evaluated. The objectives of this study were to assess the vertical variation of soil resistance to rill erosion in the WLFZ of the TGR and to identify the factors influencing these variations. Soil samples from 150-155 m, 155-160 m, 160-165 m, 165-170 m and 170-175 m were taken along a slope profile at the same time from the WLFZ of the TGR area. All the samples subjected to scour under the combinations of five slope gradients (8.74%, 17.63%, 26.79%, 36.40% and 46.63%) and five flow rates (5, 10, 15, 20 and 25 L min<sup>–1</sup>) by using a slope-adjustable steel hydraulic flume (4 m length, 0.4 m width, 0.2 m depth). The results showed that soil properties and biomass parameters were affected by the elevations of the WLFZ. The average soil detachment capacity fluctuated with the increase of elevation, maximum and minimum value of  which were located at the 165-170 m and 155-160 m, respectively. The soil detachment capacity was significantly negatively correlated with MWD (P<0.05), but not positively correlated with other properties (P>0.05).  The rill erodibility also fluctuated with the increase of elevation. Correlation analysis showed that rill erodibility corresponding to runoff shear stress and stream power respectively had significantly negative correlation with MWD (P<0.05), and rill erodibility corresponding to unit energy of water-carrying section had significant negative correlation with MWD (P<0.01). Therefore, the soil aggregate stability was the major factor responsible for the vertical variation in soil erosion resistance. In addition, critical shear stress, critical stream power and critical unit energy of water-carrying section ranged from 1.1950 to 1.6427 Pa, from 0.0132 to 0.3045 N•m<sup>-1</sup>•s<sup>-1</sup> and from 0.0052 to 0.0062 m, respectively, all of them showed obvious fluctuations with the increase of elevation. These research results highlighted the effect of elevation on soil erosion resistance in the WLFZ and provide theoretical guidance for the establishment of soil and water loss prediction model as well as the development of soil and water conservation planning and controlling in the TGR area.</p><p> </p>

Soil erosion in the riparian zone of the Three Gorges Reservoir, China

2013 ◽  
Vol 46 (2) ◽  
pp. 212-221 ◽  
Author(s):  
Yuhai Bao ◽  
Qiang Tang ◽  
Xiubin He ◽  
Yunhua Hu ◽  
Xinbao Zhang
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Water Wave ◽  
Three Gorges Reservoir ◽  
Riparian Zone ◽  
Water Levels ◽  
Three Gorges ◽  
The Three Gorges Reservoir ◽  
The Three Gorges ◽  
Wave Erosion

The riparian zone of the Three Gorges Reservoir (TGR) has experienced substantial erosion that may severely deteriorate the reservoir ecosystem. To calculate soil erosion characteristics, field investigations have been conducted in the TGR area and 12 erosion-monitoring transects have been set in the middle TGR. The results showed that the dominating drive forces are water wave, gravity and surface runoff. In summer when the reservoir ran at lower water levels, wave erosion led to bank instability and bank collapses. Simultaneously, due to a number of heavy storms, surface runoff erosion was also severe. In other seasons when the reservoir ran at relative higher levels reaching the highest level in winter, water wave prevailed due to the wide range of water surface and heavy waterway transportation. Soil erosion was the most severe in the mainstream where higher frequency and intensity of waves occurred. The rates of wave erosion were around 37 mm/year with the highest being 53 mm/year, and surface runoff erosion was up to 15 mm/year in the main stream riparian zone.

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