The hazards of debris flows and the vulnerability to these flows were used as a basis for risk assessment in Zhouqu County, southern Gansu Province, China. The GIS software was used to perform a regional risk assessment for each township in Zhouqu County with a 250 m×250 m spatial resolution. The vulnerability of the population, the economy, and the ecological environment were accounted to develop a comprehensive vulnerability index for each township. A risk assessment model was used to develop a risk zoning map for Zhouqu County. It is found that the areas with the highest risk were mainly distributed in Chengguan, Dongshan, Jiangpan, Dachuan, and Guoye townships. Based on the results of the study, the recommendations for disaster prevention and mitigation were proposed.
A village-scale approach was developed to break the cycle between desertification and poverty by providing sustainable employment and income, promoting environmental restoration by reducing water consumption, and integrating poverty amelioration with environmental restoration to ensure that solving one problem does not create new ones. The advantages of high-efficiency water-saving planting, a profitable livestock system, a sand-processing industry, and sand control and afforestation are integrated into what we call the Zhengxin pattern, which offers overall ecological and environmental benefits superior to those of competing approaches. The overall output efficiency of the Minqin basin water resources will increase threefold.
Rainfall is one of the main factors that drive soil erosion, leading to environmental problems such as increased frequency and severity of debris flows, and ecosystem damage. Rainfall erosivity represents the potential of rainfall to cause soil erosion, and is determined by a combination of rainfall intensity. The spatial and temporal distribution of rainfall erosivity was analyzed to get its relationship with the debris flows in the Bailong River Basin in China's Gansu Province. The mean annual amount of erosive rainfall accounts for 36.0-47.1% of annual precipitation. The annual mean rainfall erosivity amounts to 798.8 MJ mm ha-1 h-1 yr-1 in the Bailong River Basin. A positive correlation between annual precipitation and annual rainfall erosivity was demonstrated at all 18 rainfall stations. However, further research is required to reveal the key factors that explain soil erosion and debris flows.
Based on field surveys the geological condition was obtained on the Kangjia landslide that occurred in China’s Wenxian County. The dynamic motion of the landslide was analysised and simulated using the DAN-W software. The impact of numerical simulation of landslides was considered in terms of their erosion effects and rheological characteristics. It is found that the landslide deposit forms were similar despite different erosion depths and stacking thickness along when the erosion depth increased and the running time decreased. The maximum movement distance was estimated at 193.92 m using a frictional–Voellmy model. The maximum thickness was 7.6 m, the maximum velocity of the leading edge was 24.5 m/s, and the longest movement time was 19 s. The most suitable rheological parameters to simulate this landslide were a friction angle φ of 37°, a friction coefficient μ of 0.16, and a turbulence coefficient ξ of 800 m/s2.
In order to analyze the spatial distribution of landslides and its characteristics about the surface condition of landslides, a typical large landslide called the Xieliupo located in Zhouqu County was choosed as an example, comparing the data obtained from the field investigation with the initiatory interpretation result using remote sensing images. The results show that the proposed typical interpretation signs for landslide recognition have been improved right and could produce obvious identification results which were consistent with visual interpretation. Since the above method has been confirmed practical in the landslide recognition, we finally apply the method and experience in interpretation of landslide based on RS to the recognition of other large landslides, which can provide the theoretical basis for the subsequent research of landslides.
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