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This study aims to evaluate risk and discover the distribution law for landslides, so as to enrich landslide prevention theory and method. It first selected Fengjie County in the Three Gorges Reservoir Area as the study area. The work involved developing a landslide risk map using hazard and vulnerability maps utilizing landslide dataset from 2001 to 2016. The landslide dataset was built from historical records, satellite images and extensive field surveys. Firstly, under four primary conditioning factors (i.e., topographic factors, geological factors, meteorological and hydrological factors and vegetation factors), 19 dominant factors were selected from 25 secondary conditioning factors based on the GeoDetector to form an evaluation factor library for the LSM. Subsequently, the random forest model (RF) was used to analyze landslide susceptibility. Then, the landslide hazard map was generated based on the landslide susceptibility mapping (LSM) for the study region. Thereafter, landslide vulnerability assessment was conducted using key elements (economic, material, community) and the weights were provided based on expert judgment. Finally, when risk equals vulnerability multiplied by hazard, the region was categorized as very low, low, medium, high and very high risk level. The results showed that most landslides distribute on both sides of the reservoir bank and the primary and secondary tributaries in the study area, which showed a spatial distribution pattern of more north than south. Elevation, lithology and groundwater type are the main factors affecting landslides. Fengjie County landslide risk level is mostly low (accounting for 73.71% of the study area), but a small part is high and very high risk level (accounting for 2.5%). The overall risk level shows the spatial distribution characteristics of high risk in the central and eastern urban areas and low risk in the southern and northern high-altitude areas. Secondly, it is necessary to strictly control the key risk areas, and carry out prevention and control zoning management according to local conditions. The study is conducted for a specific region but can be extended to other areas around the investigated area. The developed landslide risk map can be considered by relevant government officials for the smooth implementation of management at the regional scale.
Yue Wang; Haijia Wen; Deliang Sun; Yuechen Li. Quantitative Assessment of Landslide Risk Based on Susceptibility Mapping Using Random Forest and GeoDetector. Remote Sensing 2021, 13, 2625 .
AMA StyleYue Wang, Haijia Wen, Deliang Sun, Yuechen Li. Quantitative Assessment of Landslide Risk Based on Susceptibility Mapping Using Random Forest and GeoDetector. Remote Sensing. 2021; 13 (13):2625.
Chicago/Turabian StyleYue Wang; Haijia Wen; Deliang Sun; Yuechen Li. 2021. "Quantitative Assessment of Landslide Risk Based on Susceptibility Mapping Using Random Forest and GeoDetector." Remote Sensing 13, no. 13: 2625.
Catering services are an essential part of urban life. The spatial structure and evolution of catering services can reflect the characteristics of an urban structure to a certain extent. In this study, we selected the main urban area of Chongqing, a typical mountainous city, as the research area. According to data sources for 200,000 catering POI data points in 2015 and 2020, we extracted the hotspots according to catering service grade based on kernel density. We quantitatively analyzed the spatiotemporal structure of catering services in the mountainous city. In addition, we used digital field hierarchical structure Tupu and generalized symmetric structure Tupu to identify the spatial morphology and evolution characteristics to enhance the understanding of geoscience trends. The results showed that (1) the distribution of catering services was statically consistent with the “multi-center group” distribution of the mountainous city and dynamically similar to the “sprawling leap” development of the mountainous city where it developed from independent points to cross mountains and rivers. Moreover, we found that there was a tendency of adhering development between groups. (2) From the perspective of symmetrical distribution, the symmetrical distribution of the catering industry reflected a certain generalized symmetrical structure with mountains and rivers in the mountainous city. Furthermore, the city tended to develop symmetrically along the topography, thus forming the symmetry of economic geography.
Yu Zhang; Jie Min; Chunxia Liu; Yuechen Li. Hotspot Detection and Spatiotemporal Evolution of Catering Service Grade in Mountainous Cities from the Perspective of Geo-Information Tupu. ISPRS International Journal of Geo-Information 2021, 10, 287 .
AMA StyleYu Zhang, Jie Min, Chunxia Liu, Yuechen Li. Hotspot Detection and Spatiotemporal Evolution of Catering Service Grade in Mountainous Cities from the Perspective of Geo-Information Tupu. ISPRS International Journal of Geo-Information. 2021; 10 (5):287.
Chicago/Turabian StyleYu Zhang; Jie Min; Chunxia Liu; Yuechen Li. 2021. "Hotspot Detection and Spatiotemporal Evolution of Catering Service Grade in Mountainous Cities from the Perspective of Geo-Information Tupu." ISPRS International Journal of Geo-Information 10, no. 5: 287.
Paddy rice is a staple food of three billion people in the world. Timely and accurate estimation of the paddy rice planting area and paddy rice yield can provide valuable information for the government, planners and decision makers to formulate policies. This article reviews the existing paddy rice mapping methods presented in the literature since 2010, classifies these methods, and analyzes and summarizes the basic principles, advantages and disadvantages of these methods. According to the data sources used, the methods are divided into three categories: (I) Optical mapping methods based on remote sensing; (II) Mapping methods based on microwave remote sensing; and (III) Mapping methods based on the integration of optical and microwave remote sensing. We found that the optical remote sensing data sources are mainly MODIS, Landsat, and Sentinel-2, and the emergence of Sentinel-1 data has promoted research on radar mapping methods for paddy rice. Multisource data integration further enhances the accuracy of paddy rice mapping. The best methods are phenology algorithms, paddy rice mapping combined with machine learning, and multisource data integration. Innovative methods include the time series similarity method, threshold method combined with mathematical models, and object-oriented image classification. With the development of computer technology and the establishment of cloud computing platforms, opportunities are provided for obtaining large-scale high-resolution rice maps. Multisource data integration, paddy rice mapping under different planting systems and the connection with global changes are the focus of future development priorities.
Rongkun Zhao; Yuechen Li; Mingguo Ma. Mapping Paddy Rice with Satellite Remote Sensing: A Review. Sustainability 2021, 13, 503 .
AMA StyleRongkun Zhao, Yuechen Li, Mingguo Ma. Mapping Paddy Rice with Satellite Remote Sensing: A Review. Sustainability. 2021; 13 (2):503.
Chicago/Turabian StyleRongkun Zhao; Yuechen Li; Mingguo Ma. 2021. "Mapping Paddy Rice with Satellite Remote Sensing: A Review." Sustainability 13, no. 2: 503.
The research on vulnerability can provide insights into social, economic, and ecological risks. Therefore, the objective of this work was to measure the degree of socio-ecological-economic system (SEES) vulnerability in Chongqing, one of the regions with the high constraint of natural conditions and human activity in the southwest of China. For this, by using three criteria and 40 indices based on the exposure-sensitive-adaptive capacity (ESC) model, an index system was designed. The entropy method was used to determine the weight of the indices. Furthermore, the composite index model and coefficient of variation were applied to evaluate the spatiotemporal characteristics of SEES vulnerability in the study area at the county level. The results showed that the average vulnerability index of SEES from 2005 to 2010 in Chongqing was 0.5735. The development pressure was high, and the ability to resist disturbance from external risks was low. Regional sustainable development was facing challenges. Spatial distribution of SEES vulnerability of Chongqing varied from high (moderately vulnerable or worse) in the western counties to low (mildly vulnerable) in the northeastern and southeastern areas with better ecological bases. The general vulnerability of the ecological and economic subsystems continues to decrease. However, the vulnerability of the social subsystem tended to initially decrease and then increase. Overall, the differences in the pattern of SEES vulnerability of the counties declined. Moreover, economic and social development tended to balance. This study is helpful to understand the overall trend and characteristics of vulnerability change and provides theoretical methods and reference opinions to support regional sustainable development.
Chunxia Liu; Qingqing He; Yuechen Li. Spatiotemporal Evaluation of Socio-Ecological-Economic System Vulnerability: A County-Level Analysis of Chongqing, China. Sustainability 2020, 12, 3912 .
AMA StyleChunxia Liu, Qingqing He, Yuechen Li. Spatiotemporal Evaluation of Socio-Ecological-Economic System Vulnerability: A County-Level Analysis of Chongqing, China. Sustainability. 2020; 12 (9):3912.
Chicago/Turabian StyleChunxia Liu; Qingqing He; Yuechen Li. 2020. "Spatiotemporal Evaluation of Socio-Ecological-Economic System Vulnerability: A County-Level Analysis of Chongqing, China." Sustainability 12, no. 9: 3912.
志明 何; He Zhiming; 月臣 李; 贤锋 金; 贤 刘; 小波 何; Li Yuechen; Jin Xianfeng; Liu Xian; He Xiaobo. 考虑太阳辐射修正的重庆山地气温空间化模拟. 资源科学 2019, 41, 1131 -1140.
AMA Style志明 何, He Zhiming, 月臣 李, 贤锋 金, 贤 刘, 小波 何, Li Yuechen, Jin Xianfeng, Liu Xian, He Xiaobo. 考虑太阳辐射修正的重庆山地气温空间化模拟. 资源科学. 2019; 41 (6):1131-1140.
Chicago/Turabian Style志明 何; He Zhiming; 月臣 李; 贤锋 金; 贤 刘; 小波 何; Li Yuechen; Jin Xianfeng; Liu Xian; He Xiaobo. 2019. "考虑太阳辐射修正的重庆山地气温空间化模拟." 资源科学 41, no. 6: 1131-1140.
The study of dynamic changes and spatial variation of landscape patterns is important to deeply understand the relationship between human activities and the natural environment. We selected a typical mountain area, Shizhu County, as the study area and analyzed the landscape’s dynamic changes and spatial variation in that area from 2000–2015. The results showed that cropland and forestland were the dominant landscape types in the study area. Cropland and grassland areas decreased, being mainly converted to forestland. Forestland and built-up land areas were increasing; the increase in built-up land was mainly due to the invasion into cropland areas, and the increase in forestland was mainly due to the conversion of cropland and grassland. Water bodies were affected by factors such as water storage in the Three Gorges Reservoir, and their area continued to increase. The change in landscape was most dramatic from 2005–2010, mainly due to the rapid increase in the areas of built-up land and water bodies and the rapid decrease in grassland area. There were apparent spatial variations in landscape distribution, patterns, and dynamic changes. Although water bodies were mainly distributed in the relatively gentle slope areas with an elevation of less than 200 m and a slope of 0°–6°, other landscapes were concentrated at an elevation higher than 500 m, a slope of 15°–35°, with a westerly or northwesterly aspect. These areas also had the most drastic landscape changes. At the type-level and the landscape-level, landscape indices showed greater variation with elevation and slope than with aspect. Finally, the variations with elevation, slope, and aspect differed among different landscape types.
Qin Chen; Yuechen Li; Chunxia Liu; Yunong Yang; Jiao Wu; Mingyang Li. Spatio-Temporal Variation in Mountainous Landscape Changes: A Case Study of Shizhu County. Sustainability 2019, 11, 2131 .
AMA StyleQin Chen, Yuechen Li, Chunxia Liu, Yunong Yang, Jiao Wu, Mingyang Li. Spatio-Temporal Variation in Mountainous Landscape Changes: A Case Study of Shizhu County. Sustainability. 2019; 11 (7):2131.
Chicago/Turabian StyleQin Chen; Yuechen Li; Chunxia Liu; Yunong Yang; Jiao Wu; Mingyang Li. 2019. "Spatio-Temporal Variation in Mountainous Landscape Changes: A Case Study of Shizhu County." Sustainability 11, no. 7: 2131.
The urban heat island (UHI) becomes more and more serious with the acceleration of urbanization. Many researchers have shown interest in studying the UHI by using remote sensing data, but these studies rarely examine the mountainous cities. Studies on UHI in mountainous cities often used empirical parameters to estimate the land surface temperature (LST), and lacked satellite-ground synchronous experiments to test the accuracy. This paper revised the parameters in the mono-window algorithm used to retrieve the LST according to the characteristics of mountainous cities. This study examined the spatial and temporal patterns of the UHI intensity in Chongqing, a typical mountainous city, and its relationship with land cover from 2007 to 2016 based on the Landsat 5 TM and Landsat 8 TIRS data and the improved method. The accuracy of the LST derivation increased by about 1 °C compared to the traditional method. The high LST areas increased and extended from the downtown to suburban area each year, but the rate of change decreased. The UHI is dramatically impacted by the rivers. There is a good relationship between the urban sprawl and the UHI. The LST was reduced by about 1 °C within a 300 m distance from large urban fringe green spaces. The urban landscape parks had a strong effect relieving the UHI at a 100 m distance. The LST was reduced by about 0.5 °C. This study greatly improves the accuracy of LST derivation, and provides reliable parameters for the UHI researched in mountainous cities.
Chunxia Liu; Yuechen Li. Spatio-Temporal Features of Urban Heat Island and Its Relationship with Land Use/Cover in Mountainous City: A Case Study in Chongqing. Sustainability 2018, 10, 1943 .
AMA StyleChunxia Liu, Yuechen Li. Spatio-Temporal Features of Urban Heat Island and Its Relationship with Land Use/Cover in Mountainous City: A Case Study in Chongqing. Sustainability. 2018; 10 (6):1943.
Chicago/Turabian StyleChunxia Liu; Yuechen Li. 2018. "Spatio-Temporal Features of Urban Heat Island and Its Relationship with Land Use/Cover in Mountainous City: A Case Study in Chongqing." Sustainability 10, no. 6: 1943.
To explore geographical differences in quantitative characteristics and spatial pattern of human settlements environmental suitability (HSES) in the Three Gorges Reservoir Area (TGRA), terrain, climate, hydrology, vegetation and other natural factors were selected to build the livable environmental evaluation, and the quantitative analysis was conducted through Remote Sensing(RS) and Geographic Informational System (GIS) to reveal geographical characteristics and spatial patterns of HSES. The results are obtained as follows: (1) inhabitants of the TGRA of Chongqing are concentrated in the area with moderate high HSES, which is 78% of the total population distributed in 48% of the study area; (2) the HSES is closely related to the terrain, and it forms an arc-banded spatial succession pattern: relatively low in the northeast and the southeast while comparatively high in the west and the south; (3) large numbers of people are distributed in the area with low suitability (with higher population density than the average of the western China), but economic development level in these areas is quite low. Moreover, these areas are ecological sensitive and fragile, many kinds of eco-environmental problems have been caused by human activities. Therefore, population migration and layout are reasonable options for the development of these areas.
Yuechen Li; Chunxia Liu; Hong Zhang; Xin Gao. Evaluation on the human settlements environment suitability in the Three Gorges Reservoir Area of Chongqing based on RS and GIS. Journal of Geographical Sciences 2011, 21, 346 -358.
AMA StyleYuechen Li, Chunxia Liu, Hong Zhang, Xin Gao. Evaluation on the human settlements environment suitability in the Three Gorges Reservoir Area of Chongqing based on RS and GIS. Journal of Geographical Sciences. 2011; 21 (2):346-358.
Chicago/Turabian StyleYuechen Li; Chunxia Liu; Hong Zhang; Xin Gao. 2011. "Evaluation on the human settlements environment suitability in the Three Gorges Reservoir Area of Chongqing based on RS and GIS." Journal of Geographical Sciences 21, no. 2: 346-358.
Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing. In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to 2004 based on RS and GIS techniques. The results showed that: (1) The soil and water loss area decreased from 1999 to 2004. (2) Soil and water loss mainly exists in purple soil, yellow soil, limestone soil, paddy soil and yellow brown soil distributed areas. (3) The dry slope land and sparse woodland that are intensively influenced by human activities experienced most serious soil and water loss. (4) Soil and water loss in the study area indicated an obvious vertical differentiation characteristic. (5) There is a significant correlation between soil and water loss and slope. (6) There is no obvious correlation between soil and water loss and aspect. (7) Soil and water loss mainly exists in the values of R between 300 and 340 distribution area. The very-high soil and water loss has obvious correlation with R.
Yuechen Li; Chunxia Liu; Xingzhong Yuan. Spatiotemporal features of soil and water loss in Three Gorges Reservoir Area of Chongqing. Journal of Geographical Sciences 2009, 19, 81 -94.
AMA StyleYuechen Li, Chunxia Liu, Xingzhong Yuan. Spatiotemporal features of soil and water loss in Three Gorges Reservoir Area of Chongqing. Journal of Geographical Sciences. 2009; 19 (1):81-94.
Chicago/Turabian StyleYuechen Li; Chunxia Liu; Xingzhong Yuan. 2009. "Spatiotemporal features of soil and water loss in Three Gorges Reservoir Area of Chongqing." Journal of Geographical Sciences 19, no. 1: 81-94.
Modeling land use/cover scenario changes and its potential impacts on structure and functions of ecosystem in typical regions are helpful to understanding the interactive mechanism between land use/cover system and ecosystem. Based on the analysis of the existing land use/cover simulation and forecast models, a land use/cover scenario dynamics model by the integration of System Dynamics (SD) model, Back Propagation Neural Network (BPNN) and Cellular Automata (CA) model is developed with land use/cover scenario changes in northern China in the next 30 years and simulated in this paper. The model is to simulate the land use/cover scenario demands by using a SD model at first, and then allocating the land use scenario patterns at the local scale with the considerations of land use/cover suitability, inheritance ability and neighborhood effect by using BPNN-CA model to satisfy the balance between land use/cover scenario demands and supplies. It integrates the advantages of SD, BPNN and CA. Macro-driving factors and the micro-spatial pattern are also fully taken into account. The BPNN simplifies the identification of the factors’ weights used in CA model and improves the reliability of the simulation results. The simulation accuracy of the model developed in this paper was found to be about 74%. It suggests that the model has the ability to reflect the complexity of land use/cover system at different scales to some extent and it is a useful tool for assessing the potential impacts of land use system on ecosystem. The simulated results also indicate that the urban land, water area and forest will increase significantly, and farmland and unable land will decrease gradually. Obvious land use/cover changes will take place in the farming-pastoral zone and the southeast area of northern China.
Yuechen Li; Chunyang He. Scenario simulation and forecast of land use/cover in northern China. Science Bulletin 2008, 53, 1401 -1412.
AMA StyleYuechen Li, Chunyang He. Scenario simulation and forecast of land use/cover in northern China. Science Bulletin. 2008; 53 (9):1401-1412.
Chicago/Turabian StyleYuechen Li; Chunyang He. 2008. "Scenario simulation and forecast of land use/cover in northern China." Science Bulletin 53, no. 9: 1401-1412.
The 13 provinces (autonomous regions and municipalities) in northern China are located in latitude 31°–54°N and longitude 73°–136°E including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Jilin, Liaoning, Heilongjiang, Shaanxi, Gansu, Ningxia, Qinghai, and Xinjiang, where environments are fragile. In recent years, the eco-environmental problems such as vegetation destruction, desertification and soil erosion etc. become serious because of climate change and unreasonable human activities. In this paper, landscape pattern and its evolution in northern China from 1989 to 2003 was investigated by the combined use of RS and GIS based on the basic theory and method of landscape ecology. Land use/cover maps of the study area in 1989, 1999 and 2003 were produced by using 1 km monthly NOAA Advanced Very High Resolution Radiometer (AVHRR) and SPOT/VGT Normalized Difference Vegetation Index (NDVI) dataset from national climate bureau of China which were geo-registered to Lambert azimuthal equal-area map projection and were used in the paper. Landscape evolution in the area over the study period was investigated by two methods: (a) the changes of various landscape metrics were analyzed using the landscape structure analysis program FRAGSTATS; (b) the transition matrix of landscape patch types was calculated with the help of the RS and GIS software. The results showed that from 1989 to 2003, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The diversity index and evenness index increased during the period, which means that the landscape pattern tended to be diversified and even. The fragmentation index of grassland, forestland and water areas also increased significantly. This showed that the distribution and structure of forestland, grassland and water areas had been changed greatly during the period, especially grassland which became more and more fragmentized, and its fragmentation index increased from 19.23% to 88.72%. The transitions of the landscape types were mainly shown by the changes among forestland, grassland and farmland, and grassland changing into unable land. Over the study period, grassland and water areas had decreased remarkably, accounting for 15% and 37% from 1989 to 1999 and 24.79% and 49.25% from 1999 to 2003 respectively. The grassland and water resources play an important role in the eco-environment and economic development of the region. So, they must be protected carefully. According to the analysis, we can conclude that the eco-environment in the study area is obviously degenerated due to unreasonable human activities and climate changes and some measures should be taken to combat the environ-mental degradation.
Yuechen Li. Land cover dynamic changes in northern China: 1989–2003. Journal of Geographical Sciences 2008, 18, 85 -94.
AMA StyleYuechen Li. Land cover dynamic changes in northern China: 1989–2003. Journal of Geographical Sciences. 2008; 18 (1):85-94.
Chicago/Turabian StyleYuechen Li. 2008. "Land cover dynamic changes in northern China: 1989–2003." Journal of Geographical Sciences 18, no. 1: 85-94.