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过刊目录

  • 2021年, 18卷, 第04期
    刊出日期：2024-06-19
      
  • 全选
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  • Spring recharge and groundwater flow patterns in flysch aquifer in the Po?onina Wetlińska Massif in the Carpathian Mountains
    Karolina MOSTOWIK, Damian KRZYCZMAN, Eliza P?ACZKOWSKA, Bart?omiej RZONCA, Janusz SIWEK, Patryk WAC?AWCZYK
    2021, 18(04): 819-833.
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    Flysch-type aquifers in the Eastern Carpathians usually feed periodic and low-discharge springs. However, in some areas, such as in the upper part of the Po?onina Wetlińska Massif, perennial springs with a relatively high discharge were identified. Therefore, the aim of this study was to identify recharge and groundwater flow patterns of three high-discharge springs based on the response of spring discharge to rainfall and on the relationship between specific electrical conductivity of water and spring discharge. The relation between spring discharge and rainfall was investigated by crosscorrelation analyses. Generally, cumulative rainfall over a period from 10 days to 3 months is most strongly correlated with discharge; however, the response time of spring discharge varies throughout the year. Faster response to rainfall occurs in the spring after snowmelt, while in the summer and autumn months the response time increases. Two flow systems were identified: 1) a relatively deep, fissure-pore flow system with a long response time to precipitation and 2) a shallow, fissure-dominated system with a short response time, which is superimposed on the longer response. A small range of specific electrical conductivity combined with the varying discharge of two springs suggests that dilution of groundwater by rainwater does not play a significant role. The differences in the studied springs' response to rainfall can be attributed to the recharge area, regolith features and local bedrock structures, i.e. occurrence of joints and faults, monoclinal dip of rock layers and gravitational slope deformations including ridge-top trenches, which, thus far, have been underestimated in determining groundwater storage capacity in the flysch part of the Carpathians.
  • Stable isotopes and chloride ion of precipitation events in the northeastern Tibetan Plateau, China
    CUI Bu-li, LI Dong-sheng, JIANG Bao-fu, WANG Ying, WANG Ya-xuan, WANG Long-sheng, LI Xiao-yan
    2021, 18(04): 834-846.
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    Stable isotopes and chloride ion of precipitation are ideal environmental tracers to explain and reveal the formation and evolution mechanisms of water bodies. It is crucial to investigate the stable isotopes and chloride in precipitation events in the northeastern part of the Tibetan Plateau(NETP) due to the limitation of available data. This study sampled each event of precipitation during the period from July 2018 to June 2019 and the monthly dustfall in the NETP to investigate the temporal changes of stable isotopes and chloride in precipitation, and to reveal the moisture source of precipitation over the NETP using a back trajectory model. Results showed that the δ2 H values of precipitation ranged from-183.51‰ to 17.75‰, and the δ18 O values ranged from-25.18‰ to 0.48‰. The slope of the Local Meteoric Water Line was slightly lower than 8 due to the effect of belowcloud secondary evaporation on the precipitation process. Most d-excess values were higher than 10‰ because moisture recycled from the continent and Qinghai Lake surface mixed with precipitation. The chloride in precipitation accounted for 86.5% of the annual total deposition mass of chloride(1329.64 mg/m2), indicating that precipitation was the main source of chloride in the NETP. The temperature and amount effects of stable isotope in the precipitation were obvious in the NETP. The precipitation was predominantly derived from the Westerly Circulation from September through May and the East Asian Monsoon from June to August, with precipitation amounts of 246.5 mm and 178.0 mm, respectively, indicating that the precipitation over the NETP brought by the Westerly Circulation was more than that brought by the East Asian Monsoon. The air mass over the NETP transited in late May and early September, and a slight change in transition period would mainly be related to the intensity of the East Asian Monsoon, which is strongly influenced by El Ni?o-Southern Oscillation. These results provide not only baseline data for hydrological and climatological studies of the NETP but also valuable insights into the hydrological process in the inland arid area of Asia.
  • Influence of tributaries on downstream bed sediment grain sizes under flysch conditions
    SMA?áK Ivan, GALIA Tomá?
    2021, 18(04): 847-862.
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    Tributaries are one of the most important factors contributing to variability in the downstream evolution of bed sediment grain size. The primary aim of this work is to evaluate the response of the bed sediment texture in the recipient channel induced by ten tributaries of the ?erná Ostravice stream and find reach-scale and catchment-scale parameters that would be able to predict this response. The research was based on collecting information on the grain size distributions at sites adjacent to confluence zones. A significant change in sediment texture occurred in the vicinity of five confluences. Considering the other factors contributing to grain size variability(e.g., local channel geometry, lithology, and lateral sediment sources), it was assumed that only four of them were associated with a sufficient bedload influx to alter the sediment calibre below the junction. Moreover, a significant morphological effect in the form of a large confluence bar was observed in one case. These tributaries had several common features:(i) they had a larger relative catchment area than that of nonsignificant tributaries;(ii) they were characterized by different bed grain sizes, with some exceptions; and(iii) they had a higher unit stream power close to the confluence in relation to that of the mainstream. These characteristics were represented by the proposed relative parameters, including the relative unit stream power and bed material texture, which allowed the best classification of significant and nonsignificant tributaries. In their simplified form, the parameters described the transport capacity and grain size distribution, which were generally considered to be primary factors responsible for a redefinition of the sediment texture in the recipient channel. However, it should be noted that these results are subject to some degree of uncertainty due to the relatively small sample size of only 10 tributaries.
  • Soil conservation assessment via climate change and vegetation growth scenarios in the Nile River basin
    LIU Hua, LIU Yan-xu, ZHAO Wen-wu, PENG Da
    2021, 18(04): 863-877.
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    Soil conservation by vegetation can mitigate soil erosion hazard and prevent reductions in food productivity. However, previous research applies little consideration to the interaction between vegetation and climate change in the estimation of future soil conservation change. Therefore, based on the Revised Universal Soil Loss Equation(RUSLE), Representative Concentration Pathways(RCPs, specifically RCP4.5 and RCP8.5), and the vegetation index and precipitation datasets, we built a multivariate regression equation that considers changes in vegetation growth under climate change scenarios in the context of soil conservation. Using the Nile River basin as a case study, via our established methods, we modelled and projected the impact of vegetation and climate change on future soil conservation between 2020 and 2100, where three main results were obtained:(1) under the scenarios of RCP4.5 and RCP8.5 from 2020 to 2100, soil conservation in the Nile Basin will first increase and then decrease, with its highest value in the years 2060, at 117.72(t ha-1 y-1), and 2070, at 134.39(t ha-1 y-1).(2) Soil conservation under RCP4.5 is lower than that under the RCP8.5 scenario, with a maximum difference of 27(t ha-1 y-1) in 2040 and a minimum difference of 0.2(t ha-1 y-1) in 2100.(3) The vegetation and climate change models in 2100 had soil conservation values of 110.77(t ha-1 y-1) under RCP4.5 and 38.70(t ha-1 y-1) under RCP8.5. In conclusion, although vegetation growth can increase soil conservation in the Nile River basin, the change in precipitation can offset the soil conservation enhanced by vegetation growth.
  • Carbon isotope variations of modern soils in the eastern margin of the Tibetan Plateau and their controlling factors
    QI Lin, QIAO Yan-song, LIU Zong-xiu, PENG Sha-sha, CHENG Yu, WANG Yan, ZHANG Xu-jiao, TIAN Ming-zhong, YANG Shuai-bin, BAI Wen-bin
    2021, 18(04): 878-890.
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    The marginal areas of the Tibetan Plateau have great vertical altitude gradient and abundant vegetation, they are therefore the ideal places for investigating the relationships among carbon isotope composition(δ~(13)C) of modern soils, vegetation and environmental factors, which would be very useful for the reconstructions of both paleovegetation and paleoclimate. In this paper, modern soil samples collected in different vegetation vertical zones along 4km elevation gradient in the eastern margin of the Tibetan Plateau were analyzed for their carbon isotope composition. The results show that the modern soils in different vegetation vertical zones show apparent difference of δ~(13)C values, which get heavier in the sequence of mixed evergreen and deciduous broad-leaved forest(-27.28‰ on average), evergreen broad-leaved forest(-27.25‰), subalpine shrub-meadow(-25.81‰), subalpine coniferous forest(-25.81‰), alpine bush-meadow(-25.16‰), and drought-enduring shrub(-24.07‰). 1800 m and 3500 m are two critical points for the δ~(13)C values with respect to altitude. Specifically, the δ~(13)C values decrease with increasing altitude below both points while increasing with increasing altitude above both points. Further analyses indicate that the declining δ~(13)C values are mainly controlled by the decreasing proportion of C4 plants with elevation and the increasing δ~(13)C values are attributed to the plant physic-morphological adaptation to the alpine environment. In the absence of drought stress, temperature is the main controlling factor for the carbon isotopic variations with altitude gradient.
  • Spatio-temporal variation of Fraction of Photosynthetically Active Radiation absorbed by vegetation in the Hengduan Mountains, China
    YANG Zheng-lan, ZHANG Ting-bin, YI Gui-hua, LI Jing-ji, QIN Yan-bin, CHEN Yang
    2021, 18(04): 891-906.
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    The Fraction of Absorbed Photosynthetically Active Radiation(FPAR) is an important indicator of the primary productivity of vegetation. FPAR is often used to estimate the assimilation of carbon dioxide in vegetation. Based on MOD15 A2 H/FPAR data product, the temporal and spatial variation characteristics and variation trend of FPAR in different vegetation types in 2001 to 2018 were analyzed in the Hengduan Mountains. The response of FPAR to climate change was investigated by using Pearson correlation analytical method and partial least squares regression analysis. Results showed that the FPAR in Hengduan Mountains presented an increasing trend with time. Spatially, it was high in the south and low in the north, and it also showed obvious vertical zonality by elevation gradient.The vegetation FPAR was found to be positively correlated with air temperature and sunshine duration but negatively correlated with precipitation. Partial least squares regression analysis showed that the influence of sunshine duration on vegetation FPAR in Hengduan Mountains was stronger than that of air temperature and precipitation.
  • Impacts of native vegetation on the hydraulic properties of the concentrated flows in bank gullies
    SU Zheng-an, HE Zhou-yao, ZHOU Tao, WANG Jun-jie, WANG Xiao-yi, WANG Li-juan, FANG Hai-dong, SHI Liang-tao, LIU Yi-han, WU Zuo
    2021, 18(04): 907-922.
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    To quantify the impacts of native vegetation on the spatial and temporal variations in hydraulic properties of bank gully concentrated flows, a series of in situ flume experiments in the bank gully were performed at the Yuanmou Gully Erosion and Collapse Experimental Station in the dry-hot valley region of the Jinsha River, Southwest China. This experiment involved upstream catchment areas withone-and two-year native grass(Heteropogon contortus) and bare land drained to bare gully headcuts, i.e., Gullies 1, 2 and 3. In Gully 4, Heteropogon contortus and Agave sisalana were planted in the upstream catchment area and gully bed, respectively. Among these experiments, the sediment concentration in runoff in Gully 3 was the highest and that in Gully 2 was the lowest, clearly indicating that the sediment concentration in runoff obviously decreased and the deposition of sediment obviously increased as the vegetation cover increased. The concentrated flows were turbulent in response to the flow discharge. The concentrated flows in the gully zones with native grass and bare land were sub-and supercritical, respectively. The flow rate and shear stress in Gully 3 upstream catchment area were highest among the four upstream catchment areas, while the flow rate and shear stress in the gully bed of Gully 4 were lowest among the four gully beds, indicating that native grass notably decreased the bank gully flow rate and shear stress. The Darcy–Weisbach friction factor(resistance f) and flow energy consumption in the gully bed of Gully 4 were notably higher than those in the other three gully beds, clearly indicating that native grass increased the bank gully surface resistance and flow energy consumption. The Reynolds number(Re), flow rate, shear stress, resistance f, and flow energy consumption in the gully beds and upstream areas increased over time, while the sediment concentration in runoff and Froude number(Fr) decreased. Overall, increasing vegetation cover in upstream catchment areas and downstream gully beds of the bank gully is essential for gully erosion mitigation.
  • arcPycor: an open-source automated GIS tool to co-register elevation datasets
    WANG Yu-zhe, YE Qing-hua
    2021, 18(04): 923-931.
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    Subtraction of elevation datasets(e.g. digital elevation models(DEMs) and non-continuous elevation points) acquired at different times is a useful method to monitor landform surface change. Due to heavy post-processing of these elevation datasets, multi-source errors are introduced into the resulting elevation data products. To improve the estimation of elevation change, co-registration of elevation datasets is a prerequisite. This paper presents an open-source automated GIS tool(arc Pycor) for co-registering elevation datasets. arc Pycor is coded in Python 2.7 and is run via Arc GIS for Desktop. The performances of arc Pycor have been evaluated using a series of experiments. In benchmark tests, the resolved co-registration vectors of arc Pycor are compared to the predefined shift vectors obtained by artificially misaligning the slave DEMs from the master elevation datasets. Results show that arc Pycor is able to co-register DEMs with relative high accuracy and can well align slave DEMs to non-continuous elevation points, which indicates its robustness in co-registering of elevation datasets. arc Pycor is also able to co-register multi-sourced DEMs of different resolutions in mountain areas.
  • Activity evolution of landslides and debris flows after the Wenchuan earthquake in the Qipan catchment, Southwest China
    SHI Qing-yun, TANG Chuan, GONG Ling-feng, CHEN Ming, LI Ning, ZHOU Wei, XIONG Jiang, TANG Hai, WANG Xiao-di, LI Ming-wei
    2021, 18(04): 932-951.
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    The Wenchuan earthquake that occurred on 12 May 2008 induced numerous landslides. Loose landslide materials were deposited on hillslopes, and deep channels were easily remobilized and transformed into debris flows by extreme rainstorms. Twelve years after the Wenchuan earthquake, debris flows were still active in the Qipangou Ravine in the quake-hit area. In this paper, we continuously tracked the spatiotemporal evolution of the landslides and vegetation restoration and evaluated the evolution of debris flow activity in the Qipan catchment with the aid of a GIS platform and field investigations from 2008 to 2019. We observed that the area with active landslides increased sharply immediately following the earthquake, and then decreased with time; however, the total area of landslides continued to increase from 6.93 km2 in 2008 to 10.55 km2 in 2019. The active landslides shifted towards lower angles and higher elevations after 2013. Since 2009, the vegetation coverage has been gradually increasing and approaching the coverage present before the earthquake as of 2019. The landslide activity was high and the vegetation recovery rates were rapidly rising during the first five years after the earthquake; the recovery rates then slowed over time. Therefore, we divided the evolution that occurred during the post landslide period into an active period(2008-2013), a self-adjustment period(2013-2026) and a stable period(after 2026). We then proposed a quantitative model to determine the trends of landslide activity rates and NDVI values in the catchment, which indicated that the landslide activities and postseismic vegetation restoration rates in this catchment will return to preseismic levels within approximately two decades. We also analysed the runout volumes of the debris flows after the earthquakes(Diexi and Wenchuan) and the standard deviation of the vegetation coverage and predicted that the debris flow activities will last for an additional 50 years or more.
  • Spatiotemporal patterns of burned areas, fire drivers, and fire probability across the equatorial Andes
    Xavier ZAPATA-RíOS, Carmen LOPEZ-FABARA, Abigail NAVARRETE, Sandra TORRES-PAGUAY, Miguel FLORES
    2021, 18(04): 952-972.
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    Field-based fire studies in the equatorial Andes indicate that fires are strongly associated with biophysical and anthropogenic variables. However, fire controls and fire regimes at the regional scale remain undocumented. Therefore, this paper describes spatial and temporal burned-area patterns, identifies biophysical and anthropogenic fire drivers, and quantifies fire probability across 6° of latitude and 3° of longitude in the equatorial Andes. The spatial and temporal burned-area analysis was carried out based on 18 years(2001-2018) of the MCD64 A1 MODIS burned-area product. Climate, topography, vegetation, and anthropogenic variables were integrated in a logistic regression model to identify the significance of explanatory variables and determine fire occurrence probability. A total of 5779 fire events were registered during the 18 years of this study, located primarily along the western cordillera of the Andes and spreading from North to South. Eighty-eight percent of these fires took place within two fire hotspots located in the northwestern and southwestern corners of the study area. Ninety-nine percent occurred during the second part of the year, between June and December. The largest density of fires was primarily located on herbaceous vegetation and shrublands. Results show that mean monthly temperature, precipitation and NDVI during the prefire season, the location of land cover classes such as forest and agriculture, distance to roads and urban areas, slope, and aspect were the most important determinants of spatial and temporal fire distribution. The logistic regression model achieved a good accuracy in predicting fire probability(80%). Probability was higher in the southwestern and northern corners of the study area, and lower towards the north in the western and eastern piedmonts of the Andes. This analysis contributes to the understanding of fires in mountains within the tropics. The results here presented have the potential to contribute to fire management and control in the region.
  • Robust design of self-starting drains using Random Forest
    GE Qi, LIU Zhong-qiang, SUN Hong-yue, LANG Dominik, SHUAI Fei-xiang, SHANG Yue-quan, ZHANG Ying-qiu
    2021, 18(04): 973-989.
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    Groundwater lowering is one of the most important countermeasures to avoid the risk of rainfall-triggered landslides. However, the long-term reliability of many drainage methods is often a matter of concern since the drains may easily get clogged. A new hydraulic-driven self-starting drainage method is presented in this paper. In the proposed Random Forest(RF) based robust design approach for the selfstarting drains, the datasets are generated using an automatically controlled numerical modeling technology. The deterministic analysis is carried out based on uncertain soil parameters and the specific designs selected using Uniform Design(UD). The ensemble of RF models is applied in the design process to improve computing efficiency. Safety requirements, design robustness, and cost efficiency are simultaneously considered utilizing multiobjective optimization. A straightforward and efficient framework that focuses on difficulties caused by an enormous design space is established for the robust design of the self-starting drains, and improved computation efficiency is achieved. The effectiveness of the proposed approach is illustrated with a case study, the Qili landslide in Zhejiang Province, China.
  • Simulation of the dynamic disturbance characteristics of the soft sediment in the Diexi ancient dammed lake, China
    WANG Xiao-qun, WEI Jie, ZHAO Jia-kang, ZHOU Zhou, HUANG Xin
    2021, 18(04): 990-1002.
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    In an earlier study of the Diexi ancient dammed lake along the Minjiang River in Southwest China, 10 disturbed layers with envelope and flame structures were found in more than 240 m of lacustrine sediments. In this paper, the soft-sediment disturbances caused by earthquakes in the Diexi ancient dammed lake were studied based on field investigations and laboratory core observations. A two-to three-degree-of-freedom spring-type earthquake simulation vibration table was used to carry out disturbance tests on lacustrine sediments under different dynamic conditions. The results support the following conclusions:(1) The disturbance layers in the lacustrine sediments were caused by strong earthquakes in the region.(2) The characteristics of the disturbance layers are related to the seismic parameters and the degree of sediment consolidation.(3) The greater the earthquake intensity is, the greater the disturbance amplitude is; moreover, the lower the consolidation degree is, the greater the disturbance amplitude.(4) The simulation tests verify that the disturbance layers in the sediments of the Diexi ancient dammed lake correspond to strong earthquakes in the region. These results are valuable for ongoing palaeoseismic research in the region.
  • Calculation of landslide occurrence probability in Taiwan region under different ground motion conditions
    SHAO Xiao-yi, XU Chong, MA Si-yuan, XU Xi-wei, J.BRUCE H.Shyu, ZHOU Qing
    2021, 18(04): 1003-1012.
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    In this study, Bayesian probability method and machine learning model are used to study the real occurrence probability of earthquake-induced landslide risk in Taiwan region. The analyses were based on the 1999 Taiwan Chi-Chi Earthquake, the largest earthquake in the history in this Region in a hundred years, thus can provide better control on the prediction accuracy of the model. This seismic event has detailed and complete seismic landslide inventories identified by polygons, including 9272 seismic landslide records. Taking into account the real earthquake landslide occurrence area, the difference in landslide area and the non-sliding/sliding sample ratios and other factors, a total of 13,656,000 model training samples were selected. We also considered other seismic landslide influencing factors, including elevation, slope, aspect, topographic wetness index, lithology, distance to fault, peak ground acceleration and rainfall. Bayesian probability method and machine learning model were combined to establish the multi-factor influence of earthquake landslide occurrence model. The model is then applied to the whole Taiwan region using different ground motion peak accelerations(from 0.1 g to 1.0 g with 0.1 g intervals) as a triggering factor to complete the real probability of earthquake landslide map in Taiwan under different peak ground accelerations, and the functional relationship between different Peak Ground Acceleration and their predicted area is obtained.
  • Mechanism of colluvial landslide induction by rainfall and slope construction: A case study
    ZHOU Zhou, SHEN Jun-hui, LI Ying, DUAN Wei-feng, YANG Ri-chang, SHU Jun-cheng, LI He-wei, TAO Sheng-yu, ZHENG Sheng-zhe
    2021, 18(04): 1013-1033.
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    The landslide hazards occurring in the complex geological genesis accumulation body are usually controlled by the coupling action of many internal and external factors. Therefore, this paper takes the dam-front Danbo accumulation body landslide of Yangfanggou hydropower station on the Yalong River as the geological prototype, and discusses the process and mechanism of slope stability degradation under the combined action of rainfall and slope construction. Based on the detailed understanding of the basic characteristics of the accumulation body, the development characteristics of the landslide and the construction situation of the slope engineering, the study conducted correlation analysis between rainfall and landslide displacement, the physical and mechanical tests of all types of rocksoil masses, and the numerical simulation testing of seepage field variation of the landslide section. It is found that the special slope structure and material composition of the old landslide accumulation layer on the upper part of the Danbo accumulation body are the internal factors for the occurrence of thrust loadinduced landslide, and the construction of the slope engineering not only creates free space conditions for sliding, but also provides channels for the infiltration of rainfall into the slope after confluence, which is an external factor that caused the mechanical properties of the sliding zone soil to gradually weaken from the trailing edge to the leading edge. The geomechanical model of such landslide is that the active section of the trailing edge produces the "source of force", the transition section of the middle section affects the occurrence of sliding, and the anti-sliding section of the leading edge controls the occurrence of landslide hazards. The results of this research provide not only a useful supplement to the theory of landslide formation mechanisms but also a scientific basis for guiding the prevention and control of similar hazards.
  • Dynamic process analysis of the Niumiangou landslide triggered by the Wenchuan earthquake using the finite difference method and a modified discontinuous deformation analysis
    HUANG Da, MENG Qiu-jie, SONG Yi-xiang, CUI Sheng-hua, CEN Duo-feng
    2021, 18(04): 1034-1048.
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    The Niumiangou landslide was the largest landslide triggered by the 2008 Wenchuan earthquake, which was significantly affected by the amplification effect of seismic acceleration. The ringshear experiments indicated that the materials in the source area of the Niumiangou landslide were subjected to friction degradation under a big shear displacement, which may result in rapid movement of the landslide. In order to better understand the landslide movement and study the effect of the friction degradation on movement mechanisms, the dynamic process of Niumiangou landslide was simulated with a new numerical method, which combines the finite difference method(FDM) and the discontinuous deformation analysis(DDA). First, the FDM was used to study the initiation time, amplification effect and velocity of the landslide. Afterwards, these initiation velocities were applied to the blocks in the DDA model by corresponding coordination in the FDM model. A displacementdependent friction model of the sliding surface was incorporated into DDA code to further understand the kinetic behavior of the landslide. The results show that the displacement-dependent friction strongly decreases the friction coefficient of sliding surface under a big displacement, which can obviously promote the run-out and velocity of landslide. The model output well matches the topographic map formed by the landslide. This implies that the proposed model can be applied to the simulation of earthquake-induced landslides with amplification effect, and the friction degradation model is important to clarify the movement mechanism of high-speed and long-distance landslides.
  • A multi-source data fusion modeling method for debris flow prevention engineering
    XU Qing-yang, YE Jian, LYU Yi-jie
    2021, 18(04): 1049-1061.
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    The Digital Elevation Model(DEM) data of debris flow prevention engineering are the boundary of a debris flow prevention simulation, which provides accurate and reliable DEM data and is a key consideration in debris flow prevention simulations. Thus, this paper proposes a multi-source data fusion method. First, we constructed 3D models of debris flow prevention using virtual reality technology according to the relevant specifications. The 3D spatial data generated by 3D modeling were converted into DEM data for debris flow prevention engineering. Then, the accuracy and applicability of the DEM data were verified by the error analysis testing and fusion testing of the debris flow prevention simulation. Finally, we propose the Levels of Detail algorithm based on the quadtree structure to realize the visualization of a large-scale disaster prevention scene. The test results reveal that the data fusion method controlled the error rate of the DEM data of the debris flow prevention engineering within an allowable range and generated 3D volume data(obj format) to compensate for the deficiency of the DEM data whereby the 3D internal entity space is not expressed. Additionally, the levels of detailed method can dispatch the data of a large-scale debris flow hazard scene in real time to ensure a realistic 3D visualization. In summary, the proposed methods can be applied to the planning of debris flow prevention engineering and to the simulation of the debris flow prevention process.
  • The untapped potential of scenic routes for geotourism: case studies of Lasocki Grzbiet and Pasmo Lesistej(Western and Central Sudeten Mountains, SW Poland)
    Dagmara CHYLI?SKA, Krzysztof KO?ODZIEJCZYK
    2021, 18(04): 1062-1092.
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    A view is often more than just a piece of landscape, framed by the gaze and evoking emotion. Without diminishing these obvious ‘tourismimportant' advantages of a view, it is noteworthy that in itself it might play the role of an interpretative tool, especially for large-scale phenomena, the knowledge and understanding of which is the goal of geotourism. In this paper, we analyze the importance of scenic drives and trails for tourism, particularly geotourism, focusing on their ability to create conditions for experiencing the dynamically changing landscapes in which lies knowledge of the natural processes shaping the Earth's surface and the methods and degree of its resource exploitation. The issues are found in both wider and local contexts. A more detailed insight has been conducted on the basis of two, although in some sense peripheral, tourism regions from the Sudeten Mountains(southwestern Poland): Lasocki Grzbiet(a ridge) and Pasmo Lesistej(a small range). The subjects of the investigation were complex: the geotourism potential of selected viewpoints located on the most scenic routes(mostly paths and forest tracks) as well as the problems of maintenance, conservation, and protection of their educational value. Our work is based on desk and field research supported by results of GIS visibility analyses(conducted in the QGIS program).
  • Spatial-temporal pattern and formation mechanism of county urbanization on the Chinese Loess Plateau
    SONG Yong-yong, MA Bei-bei, DAI Lan-hai, XUE Dong-Qian, XIA Si-you, WANG Peng-tao
    2021, 18(04): 1093-1111.
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    Urbanization is a comprehensive and complex socioeconomic phenomenon that plays an influential role in promoting global socioeconomic development. The Loess Plateau region is an important part of the China's ecological security pattern, and occupies an important position in the implementation of China's new-type urbanization strategy and the realization of the urban dream. The characteristics of the staged changes and regional differentiation of urbanization in the area from 1990 to 2018 were studied with focus on regions and subregions by selecting 341 county-level administrative units on the Chinese Loess Plateau as the research area, and employing partition analysis and geographic detector methods. This revealed the formation mechanism of the spatial differentiation pattern of urbanization on the Loess Plateau. We found that the urbanization of the Loess Plateau,previously in a slow growth phase, entered the accelerated development phase, presenting a macro pattern of high rates of urbanization in central and eastern areas and low rates in western areas. The formation of the regional differentiation patterns of urbanization on the Loess Plateau were the combined results of natural geographical and socioeconomic factors. Among these factors, the interaction of any two factors had a stronger impact on regional urbanization patterns than a single factor, which was specifically manifested as nonlinear or bi-factor enhancement effects. The findings of this paper may provide a theoretical reference and scientific basis for the scientific promotion of healthy urbanization on the Chinese Loess Plateau and the ecologically fragile areas of developing countries around the world.
  • Multiscale characteristics of the wetting deformation of Malan loess in the Yan'an area, China
    NAN Jing-jing, PENG Jian-bing, ZHU Feng-ji, ZHAO Jun-yan, LENG Yan-qiu
    2021, 18(04): 1112-1130.
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    Loess is prone to collapse upon wetting due to its open metastable structure, which poses a considerable threat to the environment, construction processes and human life. In this study, double oedometer tests and scanning electron microscopy and mercury intrusion porosimetry analyses were conducted on loess from Yan'an to study the macroscopic and microscopic characteristics of loess wetting deformation and the underlying mechanism. The wetting collapse of loess under loading depends on the changes in different microstructure levels and elements. This collapse chain reaction is manifested by the dissipation, scattering and recombination of the cementation, deformation and reorganization of the particles, blocking of the pore channels, decrease in the dominant size and volume of unstable macropores(>14 μm) and abundant mesopores(2.5-14 μm), increase in the volume of small pores(0.05–2.5 μm), and volume contraction at the macroscale. This process is dependent on the initial water content,stress level and wetting degree. These findings can facilitate collapsible loess hazard prevention and geological engineering construction.