Influence of permeability on the stability of dual-structure landslide with different deposit-bedding interface morphology: The case of the three Gorges Reservoir area, China

Abstract The characteristics and hysteresis of seepage are critical for assessing the stability of creeping soil landslides after reservoir impoundment. First, field and laboratory tests were conducted to obtain the saturated permeability coefficient of 396 soil landslides within the Three Gorges Reservoir area and trends among these results were obtained through basic statistics. Second, geological surveys show that these soil landslides are mainly composed of mixed soil-rock structures. Thus, a pressure plate instrument was used for estimating the soil-water characteristic parameters of this unsaturated soil-rock mixture. Finally, the seepage characteristics and hysteresis of the soil landslides was analyzed through numerical simulation based on obtained permeability parameters. The results of this research show that the permeability level of the soil landslides in the Three Gorges Reservoir Area is, in overall terms, good and moderate, and the permeability of the soil landslides has certain spatial distribution characteristics. Also, it was found that the parameters a and m of the unsaturated Fredlund-Xing model became larger with increasing gravel particle size, dry density, and plasticity index of the soil particle; all with decreasing gravel content. Behavior of the n parameter shows an opposite trend. Furthermore, more than 90% of landslides show seepage hysteresis as their hysteresis parameter is less than 35. Finally, it was found that the hysteresis coefficient and slope gradient are the key parameters conditioning the hysteresis of soil landslides.

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Effects of Landscape Positions and Landscape Types on Soil Properties and Chlorophyll Content of Citrus in a Sloping Orchard in the Three Gorges Reservoir Area, China

Sustainability ◽

10.3390/su13084288 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4288

Author(s):

Siyue Sun ◽

Guolin Zhang ◽

Tieguang He ◽

Shufang Song ◽

Xingbiao Chu

Keyword(s):

Soil Properties ◽

Chlorophyll Content ◽

Three Gorges Reservoir ◽

Slope Position ◽

Three Gorges Reservoir Area ◽

Three Gorges ◽

Reservoir Area ◽

The Three Gorges Reservoir ◽

The Three Gorges ◽

Landscape Types

In recent years, soil degradation and decreasing orchard productivity in the sloping orchards of the Three Gorges Reservoir Area of China have received considerable attention both inside and outside the country. More studies pay attention to the effects of topography on soil property changes, but less research is conducted from the landscape. Therefore, understanding the effects of landscape positions and landscape types on soil properties and chlorophyll content of citrus in a sloping orchard is of great significance in this area. Our results showed that landscape positions and types had a significant effect on the soil properties and chlorophyll content of citrus. The lowest soil nutrient content was detected in the upper slope position and sloping land, while the highest exists at the footslope and terraces. The chlorophyll content of citrus in the middle and upper landscape position was significantly higher than the footslope. The redundancy analysis showed that the first two ordination axes together accounted for 81.32% of the total variation, which could be explained by the changes of soil total nitrogen, total phosphorus, total potassium, available nitrogen, available potassium, organic matter, pH, and chlorophyll content of the citrus. Overall, this study indicates the significant influence of landscape positions and types on soil properties and chlorophyll content of citrus. Further, this study provides a reference for the determination of targeted land management measures and orchard landscape design so that the soil quality and orchard yield can be improved, and finally, the sustainable development of agriculture and ecology can be realized.

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