YANG Jianying, LIANG Dedong, SHI Changqing, WANG Huibo, LUO Guangtian, GONG Bo, YAN Jibin
Characteristics of runoff and sediment yield during artificial snow melting in ski slope
[Background] The density of artificial snow is much higher than that of natural one, the vegetation coverage of ski slope is low, and the feature of frozen-thawed soil has changed. After warming up in spring, the rapid melting of artificial snow will generate a large amount of melting water, and this will cause great soil erosion. Therefore, it is of great significance to study the runoff and sediment yield from artificial snow melting in ski slope. In order to study the characteristics of runoff and sediment yield from artificial snow melting on ski slope, this paper observed and studied the simple runoff plots in a field, which provides theoretical basis for ski slope construction and soil erosion control.[Methods] In this study, two runoff plots with the size of 2.5 m×10 m were set up on the intermediate ski slope of Beijing Shijinglong ski slope. Through the runoff plot observation method, the runoff flow and sediment concentration were measured and calculated in April 10 and 11, 2018, and sampled every hour.[Results] 1) Air temperature and soil temperature showed the change pattern of "Peak" type with time. The peak of temperature appeared at 14:00 and the peak of soil temperature appeared at 15:00. 2) There was a cubic function relationship between snow volume reduction and air temperature, but the fitting effect between snow volume reduction and soil temperature was not ideal. 3) The runoff flow and sediment concentration of snowmelt on the ski slope increased first and then decreased. Among them, the average runoff flow was 11.52×10-6 m3/s, the average sediment concentration was 0.30 kg/m3, and the average soil erosion modulus was 4 360 t/(km2·a), which belonged to moderate erosion. In addition, runoff flow and sediment concentration were also affected by soil, mulch and slope gradient, and the relationship between runoff flow and sediment concentration was linear.[Conclusions] Through experimental observation and analysis, it provides theoretical basis for ski slope construction and soil erosion control. More attention should be paid to surface soil improvement and vegetation construction of ski slope. The runoff and soil erosion caused from artificial snow melting can be reduced by improving the soil permeability and erodibility of ski slope. The construction of vegetation may increase the surface roughness and improve the physical and chemical properties of soil, thus it can play a role in preventing and controlling soil erosion.
ZHANG Shuai, ZHAO Shulan, LEI Xiaozhang, FU Wenxi, CHEN Zhuo
Automatic identification of typical landslides in Baxie River Basin based on region growing
[Background] The Loess Plateau is prone to a large number of landslides under the condition of concentrated rainfall in summer, which causes huge damage to local people's lives and property, rapid extraction of landslide information plays an important role in disaster response. At present, there are a large number of landslides in the Baxie River Basin of the Loess Plateau, and most of them are typical landslide. Traditional manual interpretation can effectively identify landslides, but its efficiency is extremely low. In addition, due to the restrictions of terrain and weather, the manual interpretation of typical landslides is more difficult.[Methods] On study area Baxie River Basin in the Loess Plateau, using Google Earth software to extract the images of study area,and Gaussian filter was adopted to reduce the influence of image noise on recognition results. The gray value range of the trailing edge of the interpreted landslide in the study area was used as the condition for automatic selection of seed points, then using region growing algorithm and morphological operations to realize recognition and trailing edge boundary extraction of landslides in typical landslides that has not been interpreted in the study area. Optimal region growth conditions were obtained by adjusting the growth threshold.[Results] This method automatically identified the typical landslide in the study area.The combination of morphologic open operation and close operation removed the obvious sawtooth and small burrs in the results and link the external broken lines to smooth the edges. Sobel operator combined with watershed algorithm extracted effectively the landslide's trailing edge boundary. Correct identification, wrong identification and missing identification existed in the extraction process of landslide trailing edge boundary. With the increase of the growth threshold, the divergence factor increased and the error factor decreased, indicating that the over-recognition increased and the missing recognition decreased. Three images of the Baxie River Basin in the Loess Plateau were extracted by Google Earth. The three images were identified and the landslide trailing edge was extracted by this method. Meanwhile, the three images were interpreted manually and the landslide trailing edge was drawn to verify the identification results. When the gray growth threshold is 10, the accuracy of identifying the trailing edge of landslide reached 78.94%. For new landslides, the grayscale characteristics at the back edge of the landslide body were obvious, and the identification results were good. For landslides with a long occurrence time, the surface weathering and new vegetation growth will reduce the identification accuracy of this method.[Conculsions] These suggest that the proposed method is effective to identify the typical landslides in Baxie River Basin of Loess Plateau, which provides a direction for landslide disaster assessment, rescue and reconstruction.
FANG Rui, XIN Huarong, GUO Xianjie, YOU Yinghua, LE Feng, WU Fang, ZHOU Zuyu
Function and practice of dynamic supervision system of soil and water conservation
[Background] The business requirements of dynamic supervision of soil and water conservation usually include three aspects:dynamic monitoring of regional soil and water loss, informatization supervision of production and construction projects and fine management of main projects. Due to the different requirements and purposes, the information and application results with different requirements are difficult to share, which brings difficulties to the unified supervision of water administrative departments at all levels. According to the business requirements of local government's dynamic supervision of soil and water conservation, and combining with the business logic and supervision experience of Ecological Environment Monitoring Station of Jiangsu Provincial Soil and water Conservation, the dynamic supervision analysis system of soil and water conservation was designed and conducted.[Methods] The system divides the minimum factor patch by multi-factor vector overlay analysis technology, and takes it as the supervision object. Through creating independent supervision task files for each supervision object, the task is assigned to the relevant responsible person in the region, and the task file circulation is used to promote and coordinate the implementation of specific supervision work of water administrative departments at all levels, so as to ensure all regulatory changes of task files information is transparently shared in the process.[Results] The experimental results of soil and water conservation monitoring stations in Jiangsu province show that the system takes districts and counties as the unit, it can integrate the monitoring and supervision data of three business scenarios in each district and county, and integrate the data results of different resolutions and frequencies in a hierarchical manner, so as to realize the whole process information sharing management of dynamic supervision of soil and water conservation; the minimum factor patch generated by overlay analysis can be used to realize the information sharing management of the whole process It can be implemented in the process of on-site supervision, and effectively drive the transfer of task files among users in different positions through user rights management.[Conculsions] The system improves the information management level of the comprehensive supervision of soil and water conservation of the local government in the three aspects, coordinates the task management of provincial, municipal and county-level regulatory departments, and improves the work efficiency of the comprehensive supervision.
A measurement of sustainable development of eco-economic system in the sandy land of Yulin city, Shaanxi province based on emergy analysis
[Background] Eco-economy sustainable development is an important part of China's sustainable development. At present, research on the eco-economic sustainability of ecological fragile zone in semi-arid desert area is relatively weak. Yulin city is located in the middle section of the farming pastoral ecotone in northern China and vulnerable to ecological environment. The 42% of its northern area is Mu Us Sandy Land. Studying the sustainable development of its eco-economic system is of significance for promoting environmental economic governance and sustainable development in ecologically fragile areas.[Methods] Collecting the macroeconomic and social development data and meteorological data of Yulin city from 2008 to 2018, using the emergy analysis method, the original data was divided into 5 categories according to emergy elements:renewable resources, non-renewable resources, input flow, output flow, and waste flow. The emergy of different elements was calculated, the emergy analysis table was compiled, the eco-economic evaluation system was constructed, it included the comprehensive development index of social, economic and natural subsystems, and the eco-economic development and sustainability of Yulin city from 2008 to 2018 was evaluated.[Results] 1) In general, from 2008 to 2018, the total use of emergy in Yulin city increased from 1.97×1023 to 5.33×1023 sej, and the emergy of non-renewable resources accounted for 80.49%-85.20%, belonging to the economic mode of high energy consumption. 2) From the perspective of social subsystem, the emergy per person of Yulin city increased from 4.60×1012 to 1.22×1013 sej/m2, increasing by 2.65 times. Emergy intensity was constantly strengthening, but the population carrying capacity decreased from 232 000 to 137 000, the ecological environment was not enough to support population development. 3) From the perspective of economic subsystem, the emergy money ratio decreased from 1.36×1013 to 9.17×1012 sej/$.The speed of economic development and urbanization was accelerated, but the emergy load ratio decreased from 10.13 to 7.18, the emergy production efficiency reduced. 4) From the perspective of ecological subsystem, the energy self-support ratio reached over 85%, the environment load ratio increased from 11.92% to 20.53%, and the environmental pressure was increasing. The emergy index for sustainable development ESID dropped from 253.0 to 163.60.[Conclusions] The economic development of Yulin city mainly comes from the development and utilization of local non-renewable resources. The external output energy value is insufficient. In the long run, the energy utilization structure is unreasonable, the eco-economy system presents an unsustainable development trend, and the support capacity of system resources for economic development is constantly declining. Thus the sustainable ability of regional eco-economy can be improved from the aspects of regional industrial waste gas treatment, energy structure adjustment, external resource input, etc.
LIU Jing, LIU Zhilin, DING Yinping, JIAO Yuanmei, WANG Jinliang, YANG Yanfen, WU Changrun
Network atlas analysis of China's soil and water loss research progress in the past 20 years based on CiteSpace
[Background] This work aims to explore the law and frontier trend of soil and water loss research in China and promote the development of soil and water loss research.[Methods] This paper draws on the subject literature of the core journals above the "Water and Soil loss" in the CNKI Journal as a data source, uses CiteSpace as an analytical tool, and combines the thought of bibliometrics to draw a map of soil and water erosion research progress.[Results] 1) In the past 20 years, a group of professional researchers and research teams have emerged in the field of soil and water loss research in China. The research institutions are mainly universities and research institutes. 2) From 2000 to 2009, soil and water loss research is mainly the continuation and deepening of traditional, and paid attention to the combination of multiple technologies in research methods. At the same time, the research object and content are influenced by social demand and policy orientation. 3) During the 2010-2019 period it highlights the research orientation with sustainable development as the core. The research on soil and water loss during this period is divided into four parts:methodological research, engineering research, refined regional research and ecological civilization construction, showing the characteristics of wide-ranging and multi-level research.[Conclusions] In the past 20 years, the research on soil and water loss in China has been continuously developing, the research scale has been continuously refined, the research focuses on solving practical problems, and concurrently, the research direction is obviously policy-oriented to some extent. On future research more attentions should be paid to relationship between soil and water loss and ecosystem services and ecological civilization construction, soil and water loss and beautiful China under the context of climate change. Meanwhile, communication between teams and innovation of theories and methods should be strengthened.
