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过刊目录

  • 2021年, 18卷, 第09期
    刊出日期：2024-06-19
      
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  • Tourism management in national parks: ?umava and Bayerischer Wald(Bavarian Forest) in the Czech-German borderland
    Krzysztof KO?ODZIEJCZYK
    2021, 18(09): 2213-2239.
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    Along the Czech-German border there are four national parks, two Czech and two German, arranged in cross-border ‘pairs'. This article focuses on the southern ‘pair' formed by the parks of ?umava and Bayerischer Wald(Bavarian Forest). The aim is to evaluate and compare tourism organization in their areas, taking into account selected aspects of management: the network of hiking trails with its related infrastructure, transport accessibility, a typology of tourist centers, as well as directions and destinations of tourist movements. Based on the results, it can be concluded that the availability of geographical space for tourists is much greater in the German than in the Czech national park, and the tourism infrastructure is clearly more extensive there, including the network of tourist trails. This is mainly due to the longer and fairly uninterrupted development of tourism in this area. ?umava National Park can be identified as a model in terms of how to adjust the directions of tourist movements and the layout of the tourist trail network to the needs of natural environment. On the basis of observations in both national parks, it is possible to indicate various solutions that, after appropriate adaptation, may bring benefits to other protected areas.
  • Energy poverty in the mountainous town of Metsovo, Greece
    Anastasios BALASKAS, Lefkothea PAPADA, Nikolas KATSOULAKOS, Dimitris DAMIGOS, Dimitris KALIAMPAKOS
    2021, 18(09): 2240-2254.
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    In an attempt to enhance knowledge on the energy poverty phenomenon in mountainous areas, a primary social survey was conducted in a typical mountainous town of Greece, Metsovo in the Region of Epirus. The survey recorded quantitative data of energy expenses and incomes of households and it also captured qualitative indicators related to energy poverty. The findings showed that nine out of ten households in Metsovo are exposed to energy poverty, based on the objective 10% index. The subjective indicators revealed other interesting aspects of the problem. Over one-third of the local population live in houses that are inadequately heated and/or present damp problems. Almost two-thirds of the local population have been forced to restrict other basic needs, in order to respond to high energy costs. Studying the relationships between variables of the survey also revealed some notable issues. Households inadequately heated present statistical significant correlation with the heating system used. The inadequately heated houses are also correlated with houses that presented damp-mould problems, as well as households that report arrears in energy bills. Moreover, reduction in hours of heating system operation is correlated with health problems. Current energy policy in Greece does not include specific strategies for mountainous areas, apart from some differentiations in heating oil subsidies. The great extent of energy poverty in mountainous Greece, highlighted by the present representative(with respect to mountainous Greece) study, may have irreversible social impacts. Hence, a need for specific and effective action is necessary, whose main axes should be an extensive upgrade of buildings' energy efficiency in mountainous settlements and special fuel tariffs for mountainous areas.
  • Consumer attitudes towards the mountain product label: Implications for mountain development
    BASSI Ivana, CARZEDDA Matteo, GRASSETTI Luca, ISEPPI Luca, NASSIVERA Federico
    2021, 18(09): 2255-2272.
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    To protect and promote the originality and authenticity of mountain foodstuffs, the European Union set Regulation No 1151/2012 to create the optional quality term "mountain product". Our research aimed at exploring the attractiveness of the mountain product label for consumers, considering both attitude towards the label itself and purchase intentions. We propose a model to investigate relationships between four latent constructs-mountain attractiveness, mountain food attractiveness, attitude towards the mountain product label, and purchase intention-which have been tested, thus confirming the statistical relevance of the relationships. All 47 items selected for describing the latent constructs are suitable for this purpose. Ridge and LASSO results also show that 17 items of the first three constructs are relevant in explaining purchase intentions. Some contextual variables, such as age, income, geographical origin of consumers, and knowledge of mountain products and mountains for tourism purposes, can positively influence consumers' behavior. These findings could support the design of mountain development strategies, in particular marketing actions for both the product and the territory.
  • Cryotic climate conditions and their eventual implication in the high-mountain surface of the Nevado de Toluca volcano, Mexico
    SOTO Victor
    2021, 18(09): 2273-2286.
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    The state of the cryosphere in tropical regions is of great importance because the temperature around the glaciers, permafrost and snow cover always fluctuates near the melting point. These thermal conditions and their high sensitivity to climate change cause the accelerated disappearance of these elements; therefore, it is important to know the climatic factors that regulate them, as well as the physical characteristics of each cryospheric element. Unlike glaciers, permafrost and snow cover have not been widely studied. In recent decades, the study of the glacial and periglacial environment has been carried out in intertropical mountains. However, despite the altitude of their relief and the frequent occurrence of snowfall in tropical high mountains, the conditions that determine such events have been barely analyzed; and in the case of Mexico, the volume of snowfall and its thickness have not been quantified either, as well as their corresponding duration. Consequently, this work is aimed to analyze the temperature and precipitation conditions that determine the snowfall at the higher part of the Nevado de Toluca volcano; at the same time, the conditions of the cryotic climate and their possible implication on the surface are studied. The analysis of data from 1965 to 2016, using frequency statistics, allowed to realize that snowfall occurs with low intensity, its accumulation being less than 10 cm thick and 10 mm of snow water equivalent, which causes the snowpack to stay only a few weeks on average. At the same time, it was determined that there is a significant increase in the number of freeze-thaw cycles. Therefore, due to the climate conditions and their influence on the mountain surface, it is probable that the bedrock is subject to a greater gelifraction dynamics, and the unconsolidated soil surface increases; the combination of the above could cause a greater geomorphological dynamic over time, particularly due to debris flows, and by water and wind erosion of the surface. This work is intended to serve as a reference for the high mountain environment in the intertropical regions.
  • Future variation in mountainous discharge in arid northwestern China: A basin case study
    WU Lei, LI Chang-bin, XIE Xu-hong, LV Jia-nan, WEI Jian-mei, ZHOU Xuan, YANG Lin-shan
    2021, 18(09): 2287-2303.
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    To better understand the variation in mountainous discharge(MD) in the future, a basin case study was conducted in the upstream Taolai River Basin(UTRB) in arid northwestern China. The Blaney-Criddle(B-C) equation, Budyko framework, and water balance method were coupled for MD calculations. The outputs of 10 global climate models(GCMs) are synthesized to confirm the future changes in air temperature and precipitation under 3 selected Representative Concentration Pathway(RCP) scenarios. The climate elasticity(CE) method was used to determine the variation in MD, and the influence of climate factors on that was quantitatively analyzed. The results reveal that the coupling framework of the three methods is suitable for MD determination in the UTRB. The weight-based synthesis of the 10 GCM outputs shows overall increases in temperature(T) and precipitation(P) under the 3 scenarios during most of the time until 2099. The above climate change leads to an increase in MD. According to CE analysis, the positive effectiveness of precipitation is greater than the negative effectiveness of temperature on MD variation, and the increase in precipitation would induce more MD in the UTRB. Uncertainty analysis reveals that GCM outputs dominate in predicting precipitation, while the RCP scenarios influence temperature more. Overall, under the background of climate change, the risk of extreme floods during wet years might increase, and a water deficit will still occur during normal and dry years. The study provides a case example for better understanding MD responses to climate change in the upper reaches of inland river basins. Findings are helpful for reasonable water resource development and utilization in the middle and lower reaches of these basins in the future. As in the Taolai River Basin, considering the future water demand across the whole basin, the development of watersaving technologies and reasonable industrial structures is crucial for a sustainable future.
  • Identification and spatial pattern analysis of alpine timberline by remote sensing methods in Yarlung Zangpo Grand Canyon
    ZHU Bei, WANG Shi-yan, SU Wei, CHEN Kai-qi, LIU Chang, DU Yan-liang, WANG Liang, HAN Zhen, ZOU Jiang-xiang
    2021, 18(09): 2304-2314.
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    As an important ecotone, the alpine timberline is the boundary between closed-canopy montane forest and alpine vegetation, and is highly sensitive to global and regional climate changes. We provided a way to identify and extract the alpine timberline in Yarlung Zangpo Grand Canyon Nature Reserve by using remote sensing data and spatial analysis based on land use/land cover classification and NDVI distribution characteristics. Combining DEM data, the influence of slope and aspect on the distribution of alpine timberline was explored. The results showed that the alpine timberline in Yarlung Zangpo Grand Canyon is transitional timberline, with the upper boundary approximately distributed at the elevation of 3422-4373 m, the lower boundary at approximately 3270-4164 m, with a width of about 110-280 m. Alpine timberline was mainly distributed on steep and very steep slopes ranging from 25° to 45°. The maximum elevation of both the upper and lower boundaries occurred on steep slopes. The distribution of alpine timberline varies with aspects, with sunny slopes having a higher boundary than shady slopes.
  • Tree community composition, structure and diversity along an elevational gradient in an Andean forest of Northern Ecuador
    JIMéNEZ-PAZ Rosa, WORTHY Samantha J, VALENCIA Renato, PéREZ álvaro J, REYNOLDS Alex, BARONE John A, BURGESS Kevin S
    2021, 18(09): 2315-2327.
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    The Andean forests of northern Ecuador are known for their high levels of plant diversity relative to the area they occupy. Typically, these forests grow on steep slopes that lead to dramatic habitat gradients across short distances. These extreme habitat gradients make the Andean forest ecosystem an excellent natural laboratory for understanding the effect of elevation on forest community diversity, structure and composition. We established 31 plots(50 m × 5 m) which are divided between two elevational transects in the cloud forest of the Siempre Verde Reserve in the western foothills of the Andes Mountains of northern Ecuador. All trees and tree ferns with a diameter at breast height(dbh) ≥ 5 cm were measured and identified. We examined changes in community composition, structure, and diversity along and between the elevational transects and three elevational zones: low(2437–2700 m), middle(2756–3052 m), and high(3163–3334 m). We found four main trends associated with the elevational gradients at this site:(1) community composition differed between the two transects and among the three elevational zones according to N-MDS, ANOSIM, and percentage of shared species, with some species having limited distributions,(2) metrics of community structure showed opposite relationships with elevation, depending on the transect, with the only significant relationship(negative) found between basal area and elevation in the open trail transect,(3) alpha diversity, in general, peaked at mid-elevations, and(4) beta diversity consistently increased with distance between plots along elevation. The complexity of changes in community composition, structure, and alpha diversity along elevation may be related to the heterogeneity of the environment on a local scale, such as topography, soil composition, and even human impact, or to dispersal limitation and should be investigated further. These changes in community composition and the relatively high beta diversity found at this site exemplify the biological complexity of montane forest, reinforcing arguments from other studies on the importance of their conservation.
  • Effects of soil shrinkage in permanent gullies formation: The case of Benggang erosion in the granite area of southern China
    HUANG Wan-xia, DENG Yu-song, CAI Chong-fa, JIANG Dai-hua
    2021, 18(09): 2328-2344.
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    Soil shrinkage is an important factor in slope destabilization in granitic areas, which is also one of the most important conditions for the formation of permanent gullies. This study explored the effect of soil shrinkage on permanent gullies, and Benggang erosion in granitic areas in southeastern China was used as an example. Three types of Benggang in granitic area were selected to examine the soil shrinkage of three soil layers(the lateritic, transitional and sandy layers) and their effect on the development of Benggang erosion was studied. The results show that the maximum values of COLEH and COLEV(coefficient of linear extensibility in horizontal and vertical directions, respectively) are 3.09% and 1.60% in the laterite layers, 2.71% and 2.13% in transition layers, and 1.10% and 1.82% in sandy layers, indicating that the shrinkage potential of the soil layers exhibits the following order, from highest to lowest: the laterite layer, transition layer, and sandy layer. With a decreasing volumetric water content, the linear shrinkage ratio increases gradually and eventually stabilizes, and in the laterite, transition and sandy layers, the average values of the maximum linear shrinkage are 1.50%, 2.09%, and 1.74%, respectively. Axial shrinkage is most obvious in the transition layers, in which the volume change in the form of subsidence is greater than that in other layers. The soil shrinkage curves fit the trilinear model(R2>0.9), and the soil shrinkage characteristic curves were divided into structural, basic, and residual sections. The correlation analysis shows that the soil shrinkage rate is positively correlated with clay and Fe_2 O_3 content and negatively correlated with sand content. Clay and sand contents are the most important factors influencing soil shrinkage. Soil oxides can influence soil shrinkage by affecting the particle composition of the soil, so soil shrinkage is closely related to soil clay minerals. Our findings can provide a theoretical basis for revealing the mechanism of Benggang erosion and its control.
  • Transport patterns and numerical simulation of heavy metal pollutants in soils of lead–zinc ore mines
    CAO Jie, XIE Cheng-yu, HOU Zhi-ru
    2021, 18(09): 2345-2356.
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    Exploring transport patterns of soil contaminants is essential for solving the problem of heavy metal contamination in mine soils. In this study, contamination of Pb, Zn, and Cd in the mountain soils of the lead–zinc ore mines in Ganxi Township, Hengdong County, Hunan Province, China was investigated, and their transport patterns were further explored using a soil-column model and numerical simulation techniques. In total, 111 mine soil samples were collected and placed into six experimental soil columns. By controlling the water flow, a control soil column group(CK), two mixed soil columns X_1 with daily water flows of 1 and 5 L, and three mixed soil columns X_3 with daily water flows of 2, 3, and 4 L were evaluated. The results showed that the residual fraction of Pb accounted for 71.93 % of the content on average, whereas the exchangeable fractions of Zn, Cd, and Fe-Mn oxide-bound fractions of Zn and Cd accounted for 28.60%, 31.07%, and 43.2% and 53.54% of the content, respectively. Pb, Zn, and Cd in the soils of the CK, X_1, and X_3 groups mainly were accumulated at a depth from approximately 0 to 20 cm, and the content at this depth accounted for 60.09% of that at a 0～40 cm depth. The soil at a depth range of 0～10 cm was most seriously contaminated, and the proportion of content was 32.39% of that at a 0～40 cm depth. Numerical simulation showed that on the 5 th day, the pollutant transport range was 0～24 cm, and on the 9 th day, the pollutant transport range exceeded 40 cm. On the 15 th day, the transport capacity of pollutants at depths of 0～40 cm was close to the stable state, but the soil at a depth of 0～10 cm was still heavily polluted. These results reflect the transport pattern of heavy metal pollutants in the soil of lead–zinc ore mines and may provide a reliable scientific support for the prevention of heavy metal contamination in mine environments.
  • Relationship between niche breadth and range shifts of Rhinopoma muscatellum(Chiroptera: Rhinopomatidae) in climate change scenarios in arid and semiarid mountainous region of Iran
    Sasan KAFAEI, Peyman KARAMI, Robab MEHDIZADEH, Vahid AKMALI
    2021, 18(09): 2357-2376.
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    Rapid climate change has provided the opportunity for many species to learn to adapt fast enough to modify their range distribution. The positive and negative responses of the species in terms of distribution are related to parameters such as kind of species, degree of specialization, size and movement skills, and such factors. Moving to high elevations and transitions to higher latitudes are among the strategies proposed as a solution to the negative effects of climate change. Therefore, predicting how different species respond to climate change can help predict the conservation program for them. Species distribution models(SDMs) are widely used to predict the geographical distribution of habitat suitability and species occurrence. Rhinopoma muscatellum is one of the three mousetailed bats(Rhinopomatidae) inhabiting the southeastern, southern, and southwestern parts of Iran and its distribution range to the interior and northern parts of Iran has been limited by the Elburz and Zagros Mountain. To study the effect of climate change on this species, range shifts and coverage of protected regions, 74 presence points and environmental variables(climate, topography, anthropogenic, and vegetation) in MaxEnt software were used. Before the implementation of the model, the autocorrelation of the presence points was reduced and the selection of pseudo absent points was limited by using the bias grid. Climate variables were prepared for Mid-Holocene, Current, Climate Current, and Future scenarios in 2070(RCP2.6, RCP4.5, RCP6, and RCP8.5). In order to evaluate the overlap of ecological niche, the Schoener's D and I statistic metrics were used. Also, to measure the breadth of the niches, B1(inverse concentration) and B2(uncertainty) metrics in ENMTOOLS software were employed. TSS statistics were used as a threshold. Species distribution trend changes in climatic scenarios were performed by the Mann Kendall(MK) test. Based on the results, the AUC values for current and future climate models were calculated to be 0.89 and 0.85, respectively. The distance from settlement, soil organic carbon, and altitude variables have the greatest impact on the current distribution of the species; and among the climatic variables, Isothermality(Bio3), Temperature Seasonality(Bio4), and Max Temperature of Warmest Month(Bio5) had the greatest impact on species distribution. The results showed that in climate change scenarios by 2070, the distribution range and breadth of climatic niche of Rhinopoma muscatellum will be significantly increased(P-value <0.05), habitat fragmentation will be reduced, and in RCP8.5 scenario it will reach the maximum distribution(39.38% of total Iran). This increase will cover the Elburz and Zagros mountain ranges, and a large part of the country will be suitable for the species. In response to current climate change, migration to higher latitudes was identified in this study. Among the main different classes of protected regions in Iran(National parks, Wildlife refuges, and Protected areas), protected areas in all scenarios had the most coverage of the suitable species habitat.
  • Changes in soil organic carbon, nitrogen and sulphur along a slope gradient in apple orchard soils of Kashmir Himalaya
    Javaid M DAD, Lotfollah ABDOLLAHI
    2021, 18(09): 2377-2387.
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    Accumulation and losses of soil organic carbon(SOC), total nitrogen(TN) and sulphur(S) influence food security and global warming. Therefore, their spatial distribution and variability at regional scale, and their relation to topographical variables are of great interest. In this study, the variability of SOC, TN and S content was evaluated in apple orchard soils of Kashmir region, at three depths(D1: 0-10, D2: 10-20, and D3: 20-30 cm) on slope gradient i.e.: flat, medium, and high. With an increase in slope, a significant decrease of SOC and TN was observed, with concentration of SOC and TN recorded highest(14.3±2.06 g kg~(-1) & 0.97±0.35 g kg~(-1)) in flat slope orchards and lowest(9.6±2.07 g kg~(-1) & 0.84±0.41 g kg~(-1)) in high slope orchards. On stock basis, the values recorded for flat, medium, and high slope orchards, for SOC and TN were 54.62±4.24 Mg ha~(-1) & 0.38±0.06 Mg ha~(-1), 44.13±5.11 Mg ha~(-1) & 0.32±0.09 Mg ha~(-1), and 38.73± 5.94 Mg ha~(-1) & 0.28±0.10, respectively. The differences for S concentration and stocks were modest, with flat(0.21±0.15 mg kg~(-1) & 0.09±0.0.003 Mg ha~(-1)) > high(0.16±0.07 mg kg~(-1) & 0.06±0.007 Mg ha~(-1)) > medium(0.12±0.04 mg kg~(-1) & 0.075±0.009 Mg ha~(-1)). Across slopes, SOC, TN and S decreased with increasing soil depth, suggesting clear downward trend. Overall, SOC and TN increased with the increase of altitude, precipitation and clay content while its relationship with soil acidity and soil bulk density was negative. The findings may provide scientific basis to structure agricultural development plans or prioritize regions for soil conservation efforts.
  • Combining Landsat-8 spectral bands with ancillary variables for land cover classification in mountainous terrains of northern Pakistan
    Arif UR REHMAN, Sami ULLAH, Muhammad SHAFIQUE, Muhammad Sadiq KHAN, Muhammad Tariq BADSHAH, LIU Qi-jing
    2021, 18(09): 2388-2401.
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    Landsat-8 spectral values have been used to map the earth's surface information for decades. However, forest types and other land-use/land-cover(LULC) in the mountain terrains exist on different altitudes and climatic conditions. Hence, spectral information alone cannot be sufficient to accurately classify the forest types and other LULC, especially in high mountain complex. In this study, the suitability of Landsat-8 spectral bands and ancillary variables to discriminate forest types, and other LULC, using random forest(RF) classification algorithm for the Hindu Kush mountain ranges of northern Pakistan, was discussed. After prior-examination(multicollinearity) of spectral bands and ancillary variables, three out of six spectral bands and five out of eight ancillary variables were selected with threshold correlation coefficients r2<0.7. The selected datasets were stepwise stacked together and six Input Datasets(ID) were created. The first ID-1 includes only the Surface Reflectance(SR) of spectral bands, and then in each ID, the extra one ancillary variable including Normalized Difference Vegetation Index(NDVI), Normalized Difference Water Index(NDWI), Normalized Difference Snow Index(NDSI), Land Surface Temperature(LST), and Digital Elevation Model(DEM) was added. We found an overall accuracy(OA) = 72.8% and kappa coefficient(KC) =61.9% for the classification of forest types, and other LULC classes by using the only SR bands of Landsat-8. The OA = 81.5% and KC=73.7% was improved by the addition of NDVI, NDWI, and NDSI to the spectral bands of Landsat-8. However, the addition of LST and DEM further increased the OA, and Kappa coefficient(KC) by 87.5% and 82.6%, respectively. This indicates that ancillary variables play an important role in the classification, especially in the mountain terrain, and should be adopted in addition to spectral bands. The output of the study will be useful for the protection and conservation, analysis, climate change research, and other mountains forest-related management information.
  • Mapping of geomorphic dynamic parameters for analysis of landslide hazards: A case of Yangbi river basin on the upper Lancang-Mekong of China
    GU Zhen-kui, YAO Xin, YAO Chuang-chuang, LI Cheng-gang
    2021, 18(09): 2402-2411.
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    Landslides are common hazards in orogenic belt areas. However, it is difficult to quantitatively express the driving effects of tectonic uplift and stream erosion on the occurrence of landslides on large spatial scales by conducting field investigations. In this study, we analyzed a relatively large region that extends over the Yangbi River basin on the upper Lancang-Mekong in China. A series of quantitative indices, including kernel density of the landslide(KDL), hypsometric integral(HI), steepness index(ksn), stream power(?), and stream power gradient(ω) were used to explore the promoting effects of tectonic uplift and stream action intensity on landslides by mapping geomorphic dynamic parameters combined with actual landslide data. The analysis showed that the HI value in the highest landslide risk area was approximately 0.47, and that the KDL in the region can be expressed as a function of steepness or stream power gradient of the channel network, namely, KDL = 0.0127 Ln ksn-0.0167(R~2 = 0.72, P < 0.001) and KDL = 0.0219 Ln ω-0.0558(R~2 = 0.21, P < 0.02). Therefore, the lower reach of the Yangbi River basin, with higher steepness and stream power gradient, usually has a high uplifting rate and stream incision that drives landslides and causes the entire river network system to be in a stage of longterm active erosion. Furthermore, the results suggest that sediments were being rapidly discharged from the steep tributary channels to the mainstream. This practical situation highlights that the downstream area of the river basin is a high-risk area for landslide hazards, especially in association with heavy rainfall and earthquakes.
  • Trigger mechanism of loess-mudstone landslides inferred from ring shear tests and numerical simulation
    WANG Xin-gang, LIAN Bao-qin, Liu Kai, Luo Li
    2021, 18(09): 2412-2426.
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    Whereas loess-mudstone landslides are widely distributed and frequently occurred at the loess Plateau, this type of landslides is hard to detect due to its particularity, and easily generates serious losses. To clarify the shear characteristics and formation mechanism of loess-mudstone landslides, field investigations, ring shear tests and numerical simulation analyses were performed on the loess specimens collected from the Dingjiagou landslide in Yan'an city, China. The test results showed that both the peak strength and residual strength of slip zone soils have a decreasing tendency with moisture content, while the increasing of normal stress caused an increase in the shear strength. These phenomena indicate that the rise in the moisture content induced by precipitation or the decreasing of normal stress due to excavation activities would result in the weakening of slip zone soils. Numerical simulations of the evolution process of slope failure using the finite element method were conducted based on the Mohr–Coulomb criterion. It was found that the heavy precipitation played a more important role in the slope instability compared with the excavation. In addition, the field investigation showed that loess soils with well-developed cracks and underlying mudstone soils provide material base for the formation of loess-mudstone landslides. Finally, the formation mechanism of this type of landslides was divided into three stages, namely, the local deformation stage, the penetration stage, the creeping-sliding stage. This study may provide a basis for understanding the sliding process of loess-mudstone landslides, as well as guidelines for the prevention and mitigation of loess-mudstone landslides.
  • Geomorphic effect of debris-flow sediments on the Min River, Wenchuan Earthquake region, western China
    HU Xu-dong, ZHOU Li-qin, LIU Wei-ming, WANG Hao, CUI Lei
    2021, 18(09): 2427-2440.
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    Coseismic landslides and subsequent mobilization of sediment greatly aggravated the landscape evolution and river sedimentation after the Wenchuan earthquake. The debris-flow alluvial fan and river morphological index was combined to describe quantitatively the effects of debris-flow sediment on the river characteristics in Longmen Mountains. The section of the Min River from the urban area of the Wenchuan county to the epicenter, the Yingxiu town in this county, was selected as the study area. We identified 27 river-blocking debrisflows(5 partial-, 7 semi-, 7 over semi-, and 5 fullyblocking degrees) in the study area via remote sensing interpretation and field survey. Based on this, the response of river longitudinal profile and curvature to debris-flow sediment was qualitatively and quantitatively analyzed. The results show that the channel gradient has decreased due to debris-flow aggradation, while two marked peaks in the river steepness index(ksn, represents the relative steepness degree of the channel) changed from 585 m0.9 to 732 m0.9 in zone 1, from 362 m0.9 to 513 m0.9 in zone 2. Moreover, the main channel has undergone substantial lateral migration with channel width decreased and river curvature increased. The temporal and spatial variation between river morphological characteristics and debris-flow sediments in short-term provides insights into the internal dynamic role of mass wasting processes in river morphology, which could be served as useful information for natural hazards management to prevent the river from being blocked by episodically debris flows after the earthquake.
  • CRWS-mountain Project: Coordinate remediation techniques and devices for water-soil pollution in mountain areas in China
    SONG Ling, LI Lei, ZHANG Chao-jie, HUANG Li, GUO Jin-song, ZHU Bo, ZHOU Ming-hua
    2021, 18(09): 2441-2446.
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    Rural environmental governance is an important strategy to achieve the goal of building "green liveable villages" in China. However, studies on technology and devices for pollution remediation focus mainly on urban areas; in this regard, few studies have focused on rural areas, especially mountainous or hilly areas with interflow. Coordinate remediation techniques and devices for water-soil restoration in mountain areas(CRWS-mountain), a subproject of the "environmental monitoring and remediation in rural areas" project(ERM-rural project), was undertaken to develop techniques and devices for coordinating the restoration of water and soil in rural mountainous and hilly areas with interflow. The CRWS-mountain project will attempt to explore the mechanisms of pollutant transportation and transformation in the interflow-soil-surface water system, establish in-situ and heterotopic remediation systems in landfill, towns and surrounding areas, and construct a comprehensive system for "polluted soilinterflow-surface water" by integrating all the technologies and devices at Yanting, a typical rural mountainous hilly area in Sichuan, Southwest China. We expect that after using this comprehensive system, the water quality will meet the requirements for local water function zoning. The operation cost is 10% lower than that of the existing urban equipment.
  • Influence of mountain-valley morphology on in-situ stress distribution
    ZHANG Chuan-qing, CUI Guo-jian, ZHOU Hui, YANG Fan-jie, LU Jing-jing
    2021, 18(09): 2447-2459.
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    The in-situ stress field is a key factor controlling the successful construction of a large number of underground structures in mountainous areas, and is intensively affected by the mountainvalley topography. The effects of mountain-valley morphology(the width of the mountain top platform, mountain height, slope angle, and width of the valley bottom) on the distribution of the in-situ stress field were analyzed and interpreted using numerical modeling techniques, where the spatial distribution and maximum values of the horizontal and vertical stresses were analyzed. The results showed that there existed a critical value of the topographic influence depth, where the in-situ stress distribution varied significantly as mountain-valley morphology, after which the influence diminishes. Tectonic action has a more remarkable influence on the in-situ stress distribution than gravitational action under the same mountain-valley morphology. Moreover, the relationships between the magnitudes of these stress components and the morphology variables are described using empirical formulas, which can be directly applied to different topographies to rapidly achieve a rational estimation. The findings of this study can be very useful for quickly understanding the in-situ stress distribution and as stress measurement guidelines.
  • An isolated similarity design method for shaking table tests on reinforced slopes
    WANG Zhi-jia, FAN Gang, CAO Li-cong, CHANG Jin-yuan
    2021, 18(09): 2460-2474.
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    Physical model test is an effective way to unveil the dynamic response of a slope under seismic condition. The similarity design is the key of physical model test. An isolated similarity design method for shaking table tests was proposed and verified in this work. In this method, the relevant physical quantities were divided into several subsystems and subcharacteristic equations for each subsystem were then established based on the Buckingham similarity theory. Large-scale shaking table tests on a reinforced slope were adopted herein to illustrate the application of the proposed isolated similarity design method. The similarity system for the studied slope was divided into four parts in the process of similarity design. The geometrical dimension L, density ρ and gravity g were selected as fundamental quantities for the similarity design, and four subcharacteristic equations were established for each subsystem. The dynamic responses of the recorded acceleration and axis force show that the seismic waves propagate well in the model slope. The proposed isolated similarity design method solves the conflict between the similarity requirement for all relevant physical quantities and the difficulty of test model fabrication to satisfy all similarity relations.
  • Seismic responses of slopes with different angles in coral sand
    ZHANG Yan-ling, DING Xuan-ming, CHEN Zhi-xiong, WU Qi, WANG Cheng-long
    2021, 18(09): 2475-2485.
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    This paper investigates the seismic responses of slopes in coral sand taken from a reef island in the South China Sea. A series of shaking table model tests were conducted to explore the responses of soil acceleration, excess pore pressure, and slope displacement for three slope angles(5°, 10°, and 15°). The results show that the excess pore pressure ratio of the slope decreases due to an increase in the initial shear stress when the slope angle increases. The acceleration response of the soil increases with the increase of the slope angle. The slope displacement presents substantial increments as the excess pore pressure ratio increases. In addition, the lateral movement, and slope settlement present substantial increments as the slope angle increases. No liquefaction is observed under a dynamic excitation of 0.2 g in the coral sand site. Under a dynamic excitation of 0.4 g, the site liquefies quickly, the acceleration amplification factor decreases, and the lateral movement and the settlement of the slope surface both increase compared with that under 0.2 g excitation. For the slope with an angle of 15° at 0.4 g, the flow distance of the sand strip increase by 289.47% compared with that in the 5° case. The lateral movement of the slope surface near the water level line is substantially larger than that away from the water line. The largest settlement is observed near the middle section of the slope(below the water level) under a dynamic excitation of 0.2 g. In contrast, the largest settlement under a dynamic excitation of 0.4 g occurs at the top of the slope.
  • Effect of stress paths on failure mechanism and progressive damage of hard-brittle rock
    CHEN Zi-quan, HE Chuan, HU Xiong-yu, MA Chun-chi
    2021, 18(09): 2486-2502.
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    During deep buried hard-brittle rock tunnel excavation, the surrounding rock experiences a complicated stress path and stress adjustment process. Once the adjusted stress exceeds the ultimate bearing capacity of rockmass, a rock failure mode defined as stress-cracking type will occur. In order to investigate the effect of stress paths on failure mechanism and progressive damage of deep-buried rockmass, the cyclic loading-unloading, loading-unloading, uniaxial, conventional and unloading triaxial compression tests on samples of hard-brittle sandstone were conducted. According to the experimental results, increase in the confining pressure was beneficial to improve the mechanical parameters of rock, but it will reduce the brittle failure features. Compared with conventional triaxial compression, the sandstone under unloading state had more remarkable stress drop and unstable failure characteristics. Meanwhile, it was found that the energy dissipation and energy release in the whole process of rock deformation were the internal power of driven rock progressive damage. With the increase of confining pressure, the energy hardening and energy accumulation features of rock were weakened, while the progressive damage evolution characteristics could be enhanced. In unloading state, more energy could be converted into elastic energy in the energy softening phase(σeb-σP), so that the prepeak damage rate of rock was lower than that of conventional triaxial compression state. Thus, the energy dissipation rate of rock after peak strength decreased linearly with the increase of confining pressure under conventional triaxial compression state, while in unloading state it showed the opposite law.