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过刊目录

  • 2023年, 20卷, 第03期
    刊出日期：2024-06-19
      
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  • From landslide characterization to nature reserve management: The “Scialimata Grande di Torre Alfina” landslide Geosite(Central Apennines, Italy)
    Gianluca TRONTI, Francesca VERGARI, Irene Maria BOLLATI, Filippo BELISARIO, Maurizio DEL MONTE, Manuela PELFINI, Paola FREDI
    2023, 20(03): 585-606.
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    Italy is characterized by widespread geomorphological instability, among which landslides leave impressive marks on the landscape. Nevertheless, landslide bodies may represent key sites for thematic and educational itineraries, especially in protected areas, where their management becomes an important issue. Our study focuses on the "Monte Rufeno Nature Reserve"(Central Apennines, Italy), where iconic landslides are present. Here, the "Scialimata Grande di Torre Alfina" landslide(SGTA) is listed in the regional Geosite database. This work aims to propose a multiscale procedure for landslide analysis, in terms of both hazard sources but also educational and geoheritage enhancement opportunities in natural reserves. After performing a Landslide Susceptibility conditional Analysis(LSA) for the reserve territory, attention was focused on the SGTA, to define properly its features and morphodynamics. A multi-disciplinary approach was adopted, by applying both remote sensing(UAV structure from motion, Photointerpretation) and field survey(geomorphological and GPS monitoring). From the LSA, based on drainage density, curvature, and slope triggering factors, the road and trail susceptibility maps were derived, as base tools for future risk assessments and trail paths management within the reserve. At the SGTA scale, the monitoring showed a displacement of up to 23 m during the time interval between 2015 and 2018. The landslide dynamics seem to be driven by alternating dry and extremely wet periods; moreover, leaks from the aqueduct in the detachment area and piping effects through clays may have also decreased the substrate cohesion. The SGTA complex influence on the Paglia River valley geometry was also hypothesized, underlining the action of landslide through different spatial scales(on-site and off-site) and on different environment features(sediment connectivity, hydrology). Finally, the SGTA appears highly representative of the geomorphic dynamics within the Nature Reserve(i.e., scientific value) and it could be classified as an active geosite. Since the site was featured by a tourist trail, adequate management strategies must be adopted, considering the educational value and safety issues.
  • Distribution patterns of landslides triggered by the 2022 MS 6.8 Luding earthquake, Sichuan, China
    ZHANG Jian-qiang, YANG Zong-ji, MENG Qing-kai, WANG Jiao, HU Kai-heng, GE Yong-gang, SU Feng-huan, ZHAO Bo, ZHANG Bo, JIANG Ning, HUANG Yu, MING Zai-yang, ZHANG Yi-fan, LIU Zhen-xing, WU Chun-hao, ZHOU Wen-tao, LIANG Xin-yue, SUN Yu-qing, YANG Lian-bing, YAO Hong-kun, FENG Pei-hua, LIU Jia-li
    2023, 20(03): 607-623.
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    At 12:52 pm on September 5, 2022, an MS 6.8 earthquake occurred in Luding County, Sichuan Province, China. Based on high-resolution aerial photographs and satellite imageries obtained after the earthquake, as well as field investigation, a total of 8685 earthquake-triggered landslides(EQTLs) were interpreted. The landslides covered an area of 30.7km2, with a source area of 9.4 km2. These EQTLs were mainly distributed in areas with a seismic intensity of VIII and IX. Most of the landslides were small and medium in size, and their types included landslide,rockfall, and rock slump. Characteristic landslide distributions were found, EQTLs were distributed along the Xianshuihe fault, landslide area decreased gradually with an increased distance to the fault;EQTLs were distributed along the Daduhe River and roads; besides, landslide distribution was associated with ground deformation caused by the earthquake.EQTLs' characteristics indicated that, a large number of EQTLs were located near the foot of the slope; the full area of EQTLs and their source area followed a power function. This study concluded that Luding EQTLs were greater in number and area but relatively smaller in terms of affected area. Investigations on geo-hazards post-earthquake and risk assessment were proposed in the earthquake-stricken area to support the rehabilitation and reconstruction.
  • Coseismic landslide sediment increased by the “9.5” Luding earthquake,Sichuan, China
    XIONG Jiang, CHEN Hua-yong, ZENG Lu, SU Feng-huan, GONG Ling-feng, TANG Chen-xiao
    2023, 20(03): 624-636.
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    The "9.5" Luding earthquake(Ms 6.8),which occurred on September 5,2022,has triggered thousands of landslides,and caused coseismic landslide sediment in the mountain basin to increase significantly.After the Luding earthquake,landslide sediment may continue to divert to channels,and increase the activity of debris flows.Importantly,the formation of debris flows can pose a major threat to infrastructure,lives and property.To better understand the landslide sediment that increased by the "9.5" Luding earthquake and its impact on the activity of debris flows,we mapped the coseismic landslide database using satellite images.A total of9142 landslides with an area of 49.51 km~2,covering4.81% of the whole basin,were triggered by the Luding earthquake.The coseismic landslides induced by this earthquake are dominated by shallow landslides and are densely distributed in the combined zone of the Xianshuihe fault and the Daduhe fault.Approximately 333.31×10~6 m~3(error:111.43×10~6 m~3/-70.73×10~6 m~3) of coseismic landslide sediments were induced by the earthquake in the epicenter,and the landslide materials were concentrated downstream of the basins.In addition.more than 13986.45×10~4 m~3(error:4675.67×10~4 m~3/-2967.92×10~4 m~3) of landslide sediment may supply for debris flow occurrence.Simultaneously,the small basins that are distributed near Moxi,Detuo and the junction of the Xianshuihe fault and Daduhe fault are more susceptible to debris flows when rainstorms hit these regions.Therefore,prevention and mitigation measures,early warning,and land use planning should be adopted in advance in these regions.However,from the perspectives of landslide scale and the degree of landslide-channel coupling,the activity or active intensity of debris flows in the Luding earthquake area may be lower than that in the epicenter area of the 2008 Wenchuan earthquake.
  • Landslide displacement prediction based on optimized empirical mode decomposition and deep bidirectional long short-term memory network
    ZHANG Ming-yue, HAN Yang, YANG Ping, WANG Cong-ling
    2023, 20(03): 637-656.
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    There are two technical challenges in predicting slope deformation. The first one is the random displacement, which could not be decomposed and predicted by numerically resolving the observed accumulated displacement and time series of a landslide. The second one is the dynamic evolution of a landslide, which could not be feasibly simulated simply by traditional prediction models. In this paper, a dynamic model of displacement prediction is introduced for composite landslides based on a combination of empirical mode decomposition with soft screening stop criteria(SSSC-EMD) and deep bidirectional long short-term memory(DBi-LSTM) neural network. In the proposed model, the time series analysis and SSSC-EMD are used to decompose the observed accumulated displacements of a slope into three components, viz.trend displacement, periodic displacement, and random displacement. Then, by analyzing the evolution pattern of a landslide and its key factors triggering landslides, appropriate influencing factors are selected for each displacement component, and DBi-LSTM neural network to carry out multi-datadriven dynamic prediction for each displacement component. An accumulated displacement prediction has been obtained by a summation of each component. For accuracy verification and engineering practicability of the model, field observations from two known landslides in China, the Xintan landslide and the Bazimen landslide were collected for comparison and evaluation. The case study verified that the model proposed in this paper can better characterize the "stepwise" deformation characteristics of a slope. As compared with long short-term memory(LSTM) neural network, support vector machine(SVM), and autoregressive integrated moving average(ARIMA) model, DBi-LSTM neural network has higher accuracy in predicting the periodic displacement of slope deformation, with the mean absolute percentage error reduced by 3.063%,14.913%, and 13.960% respectively, and the root mean square error reduced by 1.951 mm, 8.954 mm and 7.790 mm respectively. Conclusively, this model not only has high prediction accuracy but also is more stable, which can provide new insight for practical landslide prevention and control engineering.
  • Application of logistic regression model for hazard assessment of landslides caused by the 2012 Yiliang Ms 5.7 earthquake in Yunnan Province, China
    JIN Jia-le, CUI Yu-long, XU Chong, ZHENG Jun, MIAO Hai-bo
    2023, 20(03): 657-669.
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    Accurate assessment of seismic landslides hazard is a prerequisite and foundation for postdisaster relief of earthquakes. An Ms 5.7 earthquake occurring on September 7, 2012, in Yiliang County,Yunnan Province, China, triggered hundreds of landslides. To explore the characteristics of coseismic landslides caused by this moderate-strong earthquake and their significance in predicting seismic landslides regionally, this study uses an artificial visual interpretation method based on a planet image with 5-m resolution to obtain the information of the coseismic landslides and establishes a coseismic landslide database containing data on 232 landslides.Nine influencing factors of landslides were selected for this study: elevation, relative elevation, slope angle, aspect, slope position, distance to river system,distance to faults, strata, and peak ground acceleration. The real probability of coseismic landslide occurrence is calculated by combining the Bayesian probability and logistic regression model.Based on the coseismic landslides, the probabilities of landslide occurrence under different peak ground acceleration are predicted using a logistic regression model. Finally, the model established in this paper is used to calculate the landslide probability of the Ludian Ms 6.5 earthquake that occurred in August 2014, 78.9 km away from the macro-epicenter of the Yiliang earthquake. The probability is verified by the real coseismic landslides of this earthquake, which confirms the reliability of the method presented in this paper. This study proves that the model established according to the seismic landslides triggered by one earthquake has a good effect on the seismic landslides hazard assessment of similar magnitude, and can provide a reference for seismic landslides prediction of moderate-strong earthquakes in this region.
  • Refined mathematical model for the breaching of concrete-face sand-gravel dams due to overtopping failure
    QIU Wen, LI Yan-long, WEN Li-feng, WANG Jing, YIN Qiao-gang
    2023, 20(03): 670-687.
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    Overtopping is one of the main reasons for the breaching of concrete-face sand-gravel dams(CFSGDs). In this study, a refined mathematical model was established based on the characteristics of the overtopping breaching of CFSGDs. The model characteristics were as follows:(1) Based on the Renormailzation Group(RNG) k-ε turbulence theory and volume of fluid(VOF) method, the turbulent characteristics of the dam-break flow were simulated,and the erosion surface of the water and soil was tracked;(2) In consideration of the influence of the change in the sediment content on the dam-break flow, the dam material transport equation, which could reflect the characteristics of particle settlement and entrainment motion, was used to simulate the erosion process of the sand gravels;(3) Based on the bending moment balance method, a failure equation of the concrete face slab under dead weight and water load was established. The proposed model was verified through a case study on the failure of the Gouhou CFSGD. The results showed that the proposed model could well simulate the erosion mode of the special vortex flow of the CFSGD scouring the support body of the concrete face slab inward and reflect the mutual coupling relationship between the dam-break flow, sand gravels, and concrete face slabs.Compared with the measured values, the relative errors of the peak discharge, final breach average width, dam breaching duration, and maximum failure length of the face slab calculated using the proposed model were all less than 12%, thus verifying the rationality of the model. The proposed model was demonstrated to perform better and provide more detailed results than three selected parametric models and three simplified mathematical models. The study results can aid in establishing the risk level and devising early warning strategies for CFSGDs.
  • Laboratory-scale investigation of the material distribution characteristics of landslide dams in U-shaped valleys
    JIAN Fu-xian, CAI Zheng-yin, GUO Wan-li
    2023, 20(03): 688-704.
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    Material distribution characteristics during sliding and depositing is particularly significative to investigate the internal structure and spatial variation of landslide dams, which are fundamentally determining the mechanical and hydraulic behavior and the susceptibility to cause dam failure. However, limited by longevity shortages and special geographic environments, the material distribution characteristics and their formation mechanisms are difficult to observe in the field.Therefore, an experimental apparatus modeling a landslide dam was developed in this paper, designing three sampling methods with two valley states. The internal deposit characteristics, void ratio variation and relative content of the particle size range(PSR)were analyzed, and the mechanics of deposit structure were also delicately ascertained. The results indicate that granular material deposited in valley shows a structure of inverse grain size accumulation in both vertical and horizontal directions, exhibiting spatial variability of particle gradation and void ratio. The characteristic PSR decreases from 22-30 mm in the two-dimensional state to 10-14 mm in the threedimensional state. Vibration excitation and vibration sieve are the intrinsic mechanisms of granular flow segregation, intrinsically inducing the formation of inverse grading deposit structures. Consequently,spatial variability in size is mainly trig gered by segregation, whereas coarse particle content and deposition boundaries merely exacerbate the difference degree.
  • Comprehensive isotopic characterization of the hydrological processes of the Indus river basin(IRB): A comparison between Upper Indus Basin(UIB) and Lower Indus Basin(LIB)
    Akhtar JAHAN, Tanveer DAR, Sudhir KUMAR, Nachiketa RAI
    2023, 20(03): 705-723.
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    The Indus river basin(IRB) is one of the most depleted water basins globally,having significant challenges for its water sector.Monitoring of stable isotope composition(δ~(18)O and δ~2H) across IRB is a critical aspect that can provide deeper insights for investigating complex hydrological processes.This work analyses the spatial pattern of the isotopic signature using a comprehensive compilation of available datasets of the Global Network of Isotopes in River(GNIR) and Global Network of Isotopes in Precipitation(GNIP),along with the previously published isotopic studies in the Indus basin.Additionally,this work provides a detailed comparison of the isotopic signature of the Upper Indus Basin(UIB),and Lower Indus Basin(LIB).The IRBs waterline was found to be δ~2H=7.89 × δ~(18)O+13.51,which shows a close similarity with the Global Meteoric Water Line(GMWL),indicating the meteoric origin of the water with insignificant secondary evaporation prevailing across the basin.The Main Indus Channel(MIC) river water line(δ~2H=8.88× δ~(18)O+26.05) indicates a major contribution from the meteoric origin(precipitation/rain) of water with minimal effect of evaporation processes.The water line for UIB samples,(δ~2H=7.88× δ~(18)O+11.94) was found to be moderately higher in slope than LIB samples(δ~2H=7.17× δ~(18)O+7.16).However,the slopes of both UIB and LIB river water lines closely approached the slope of GMWL and were consistent with the slope of IRB water line,which indicates similarity in contribution of water sources.The higher slope and intercept in UIB suggest that meteoric water sources contributed to streamflow viz.from snow/glacier with insignificant evapotranspiration,which is also validated by the scarce vegetation cover in the UIB.However,the lower slope and intercept in LIB suggest stream water contribution from significantly evaporated groundwater and precipitation with a complete homogenization of discharge coming from the UIB.Results substantiate that distinct isotopic signatures found in different stretches of the IRB and along the MIC are caused by variations in basin characteristics,hydro-meteorological processes,water mixing,and minor influence of anthropogenic variables.
  • Individual tree segmentation and biomass estimation based on UAV Digital aerial photograph
    SUN Zhao, WANG Yi-fu, DING Zhi-dan, LIANG Rui-ting, XIE Yun-hong, LI Rui, LI Hao-wei, PAN Lei, SUN Yu-jun
    2023, 20(03): 724-737.
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    Digital aerial photograph(DAP) data is processed based on Structure from Motion(Sf M)algorithm and regional net adjustment method to generate digital surface discrete point clouds similar to Light Detection and Ranging(LiDAR) and digital orthophoto mosaic(DOM) similar to optical remote sensing image. In this study, we obtained highresolution images of mature forests of Chinese fir by unmanned aerial vehicle(UAV) flying through crossroute flight, and then reconstructed the threedimensional point clouds in the UAV aerial area by SfM technique. The point cloud segmentation(PCS)algorithm was used for the individual tree segmentation, and the F-score of the three sample plots were 0.91, 0.94, and 0.94, respectively.Individual tree biomass modeling was conducted using 155 mature Chinese fir forests which were correctly segmented. The relative root mean squared error(rRMSE) values of random forest(RF), bagged tree(BT) and support vector regression(SVR) were 34.48%, 35.74% and 40.93 %, respectively. Our study demonstrated that DAP point clouds had great potential to extract forest vertical parameters and could be applied successfully in individual tree segmentation and individual tree biomass modeling.
  • Lakes in the Qinghai-Tibet Plateau are conducive to regional permafrost development
    XIE Chang-wei, YANG Gui-qian, WANG Wu, ZHANG Yu-xin, LIU Wen-hui, LIU Guang-yue, WU Ji-chun, PANG Qiang-qiang
    2023, 20(03): 738-749.
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    The Qinghai-Tibet Plateau(QTP)possesses the largest areas of permafrost in the midand low latitude regions on the earth and many large lakes in the permafrost area. Based on a comprehensive investigation around certain typical lakes, this study found that although the presence of lakes formed different ranges of unfrozen zones in permafrost, the heating effect of lake water on surrounding permafrost is limited to a small extent.The temperature of permafrost around the lake is closely related to the distance to the lake and the ice content of the permafrost. Around lakes are ice-rich permafrost zones and permafrost temperature in this area is significantly lower than that far away from the lake, which indicates that the existence of lakes in the QTP has special effect on the permafrost distribution.Based on the monitoring results, this study presents the typical distribution pattern of the permafrost around large lakes and discusses the reasons for the distribution pattern. Due to the huge area of lakes and the significant impact of lakes on permafrost distribution, it is suggested to re-estimate the total permafrost area and underground ice storage in the QTP.
  • Soil pH and dissolved organic carbon shape microbial communities in wetlands with two different vegetation types in Changdu area, Tibet
    ZOU Lan, BAI Yin-ping, HUANG Jing, XIAO De-rong, YANG Gang
    2023, 20(03): 750-764.
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    Soil microorganisms play pivotal roles in element biogeochemical cycling and ecological functions in wetland ecosystem, which may affect global climate change. Variations in biotic and abiotic factors are known to affect soil microbial diversity,community structure and the corresponding functions. However, the relative importance of these biotic and abiotic factors on wetland soil microbial diversity and community structure on the QinghaiTibet Plateau remains poorly understood. In this study, we explored soil bacterial and fungal diversity and composition of five wetlands under two vegetation types(herbs vs Hippophae thibetana) in Changdu area, Tibet, through Illumina high throughput sequencing analysis of 16S rRNA for bacteria and internal transcribed spacer(ITS) for fungi. Results showed that soil bacterial alpha diversity was higher in H. thibetana dominated wetlands and was significantly and positively correlated with soil pH. No difference was detected in the soil fungal alpha diversity among samples and between vegetation types. The dominant soil bacterial phyla were Proteobacteria,Actinobacteria,Acidobacteria, and Firmicutes. While Ascomycota,Basidiomycota and Mucoromycota were the dominant fungal phyla. Soil bacterial and fungal community structures were significantly distinct by vegetation types. In addition, redundancy analysis indicated that soil pH was the key factor shaping soil bacterial community structure. Nevertheless, soil p H showed no effect on fungal community. Instead, soil dissolved organic carbon was the major factor contributing to soil fungal community structure. This study emphasized that wetland soil microbial communities were distinct by vegetation types and the driving factors of microbial beta diversity between bacterial and fungal community were also different in wetlands in Changdu area.
  • Adaptive mechanisms of Ardisia crenata var. bicolor along an elevational gradient on Gaoligong Mountain, Southwest China
    AI Xing-mei, LI Yu, XIE Huan, ZHAO Cai-bao
    2023, 20(03): 765-778.
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    Plants overcome environmental stress by generating metabolic pathways. Thus, it is crucial to understand the physiological mechanisms of plant responses to changing environments. Ardisia crenata var. bicolor has an important ornamental and medicinal value. To reveal the impact of elevational gradient on the habitat soil and plant physiological attributes of this species, we collected root topsoil(0–20 cm) and subsoil(20–40 cm) samples and upper leaves at the initial blooming phase, in a survey of six elevations at 1,257 m, 1,538 m, 1,744 m, 1,970 m,2,135 m, and 2,376 m, with 18 block plots, and 5sampling points at each site. Temperature decreases with an increase in elevation, and soil variables, and enzymatic activities fluctuated in both the topsoil and subsoil, with all of them increasing with elevation and decreasing with soil depth. Redundancy analysis was conducted to explore the correlation between the distribution of A. crenata var. bicolor along the elevational gradient and soil nutrients and enzyme activities, the soil properties were mainly affected by p H at low elevations, and governed by total phosphorus(TP) and available nitrogen(AN) at high elevations. The levels of chlorophyll, carbohydrates,and enzymatic activity except for anthocyanin in this species showed significant variation depending on physiological attributes evaluated at the different collection elevations. The decline in chlorophyll a and b may be associated with the adaptive response to avoid environmental stress, while its higher soluble sugar and protein contents play important roles in escaping adverse climatic conditions, and the increases in activities of antioxidant enzymes except peroxidase(POD) reflect this species' higher capacity for reactive oxygen scavenging(ROS) at high elevations. This study provides supporting evidence that elevation significantly affects the physiological attributes of A. crenata var. bicolor on Gaoligong Mountain, which is helpful for understanding plant adaptation strategies and the plasticity of plant physiological traits along the elevational gradients.
  • Effects of long-term grazing exclusion on vegetation structure, soil water holding capacity, carbon and nitrogen sequestration capacity in an alpine meadow on the Tibetan Plateau
    YANG Yong-sheng, ZHANG Fa-wei, XIE Xian-rong, WANG Jun-bang, LI Ying-nian, HUANG Xiao-tao, LI Hui-ting, ZHOU Hua-kun
    2023, 20(03): 779-791.
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    Grazing exclusion is one of the primary management practices used to restore degraded grasslands on the Tibetan Plateau. However, to date,the effects of long-term grazing exclusion measures on the process of restoring degraded alpine meadows have not been evaluated. In this study, moderately degraded plots, in which the vegetation coverage was approximately 65% and the dominant plant species was Potentilla anserina L, with grazing exclusion for 2 to 23 years, were selected in alpine meadows of Haibei in Qinghai-Tibet Plateau. Plant coverage, plant height, biomass, soil bulk density, saturated water content, soil organic carbon(SOC) and total nitrogen(TN) were evaluated. The results were as follows:(1)With aboveground biomass and total saturated water content at 0-40 cm depth, the average SOC and TN contents in moderately degraded alpine meadows increased as a power function, and the plant height increased as a log function.(2) The average soil bulk density at 0-40 cm depth first decreased and then increased with increasing grazing exclusion duration,and the minimum value of 0.90 g·cm-3 was reached at 15.23 years. The plant coverage, total belowground biomass at 0-40 cm depth, total aboveground and belowground biomass first increased and then decreased, their maximum values(80.49%, 2452.92g·m~(-2), 2891.06 g·m~(-2)) were reached at 9.41, 9.46 and 10.25 years, respectively. Long-term grazing exclusion is apparently harmful for the sustainable restoration of degraded alpine meadows. The optimal duration of grazing exclusion for the restoration of moderately degraded alpine meadows was 10 years. This research suggests that moderate disturbance should be allowed in moderately degraded alpine meadows after 10years of grazing exclusion.
  • Abandoned land identification in karst mountain area based on time series SAR characteristics at geo-parcels scale
    ZHOU Zhong-fa, WANG Ling-yu, CHEN Quan, LUO Jian-cheng, ZHAO Xin, ZHANG Shu, ZHANG Wen-hui, LIAO Juan, LYU Zhi-jun
    2023, 20(03): 792-809.
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    Mapping abandoned land is very important for accurate agricultural management.However, in karst mountainous areas, continuous high-resolution optical images are difficult to obtain in rainy weather, and the land is fragmented, which poses a great challenge for remote sensing monitoring of agriculture activities. In this study, a new method for identifying abandoned land is proposed: firstly, a few Google Earth images are used to transform arable land into accurate vectorized geo-parcels; secondly, a time-series data set was constructed using Sentinel-1A Alpha parameters for 2020 on each farmland geoparcel; thirdly, the semi-variation function(SVF) was used to analyze the spatial-temporal characteristics,then identify abandoned land. The results show:(1)On the basis of accurate spatial information and boundary of farmland land, the SAR time-series dataset reflects the structure and time-series response.abandoned land with an accuracy of 80.25%. The problem of remote sensing monitoring in rainy regions and complex surface areas is well-resolved.(2) The spatial heterogeneity of abandoned land is more obvious than that of cultivated land within geoparcels. The step size for significant changes in the SVF of abandoned land is shorter than that of cultivated land.(3) The SVF time sequence curve presented a strong peak feature when farmland was abandoned. This reveals that the internal spatial structure of abandoned land is more disordered and complex. It showed that time-series variations of spatial structure within cultivated land have broader applications in remote sensing monitoring of agriculture in complex imaging environments.
  • Assessing anthropogenic pressure and threats on Paeonia emodi Wall. ex Royle habitats in Garhwal Himalaya
    Praveen JOSHI, Prem PRAKASH, Vijay Kant PUROHIT
    2023, 20(03): 810-820.
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    The Garhwal Himalaya is among the major repositories of immensely valuable wild edible plants and provides food security to the local population.Among the valuable plant species that grow in this region, Paeonia emodi(family Paeoniaceae) is an important wild edible species that found in temperate regions with an altitude range between 1800 and 2800 m. The species is facing a severe threat to its sustainability due to overharvesting, habitat disturbances, and a lack of effort regarding conservation. For the first time, this study investigated anthropogenic pressure, population decline perceptions in the natural habitat, and vulnerability assessment of P. emodi under selected study sites(n=23 villages). A semi structured questionnaire was used to interview approximately 45%of the local inhabitants, including herbal practitioners(Vaidhyas or Dais) of each village. On the basis of demographic characteristics, the perceptions and responses of 464 local people were documented regarding potential causes of deterioration and feasible options for sustainable utilization. Using the weight survey method, we estimated the actual amount of collection based on personal interaction and direct observation. In order to determine the threats status, a rapid vulnerability assessment(RVA)was performed and were used based on the current exploitation and usage. The present study revealed that leaf(100%) was the most frequently harvested part, followed by stem(95.65%), seed(26.09%), root(21.74%) and flower(13.04%). The village Triyuginarayan and Pothivasa recorded the highest collection scores while the purpose of the collection was mostly edible(100%), medicinal(100%), and least commercial(8.70%). According to the literature review and the present survey, the RVA(total = 21) is categorized as category II(intermediate side of the RVA index), indicating a degree of vulnerability. The study revealed that P. emodi faces extinction in the Garhwal Himalayas. Growing this species through agro-production techniques may alleviate the pressure on the existing population as a result of the availability of raw materials for commercial and household uses. These findings will provide an effective framework for conservation and management decisions and plans.
  • Impact of slope farmland use change on ecosystem services value in China, 2000-2020
    ZENG Jie, BIAN Jiao-jiao, CHEN Wan-xu
    2023, 20(03): 821-833.
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    Slope farmland is an important component of farmland resources in China. The utilization and change of slope farmland have significant effects on ecosystems, and understanding the impact of slope farmland change on ecosystem services(ESs) is critical for effective land utilization and ecosystem protection. This study aims to analyze slope farmland changes in China between 2000 and 2020 and quantify the impact of these changes on ESs by the use of a land use dynamic attitude study, and an ecosystem services value(ESV) equivalent. Results show that the area of slope farmland in China was mainly concentrated on slopes of 2°-6°, and exhibited a downward trend between 2000 and 2020. There were significant differences in the spatial distribution of the farmland, which was mainly located in the Taihang, Qinling, Wushan, and Xuefeng mountains.ESV increased by $179.235 million due to the conversion between slope farmland and forest,grassland, and construction land from 2000-2010.Conversely, from 2010 to 2020, ESV decreased by $2613.919 million due to the conversion of forest and grassland to slope farmland as well as the conversion of slope farmland to construction land.
  • Strength characteristics of rock anchored by NPR bolt with different preloads
    SUN Xiao-ming, CUI Li, ZHANG Yong, WANG Lei, JIANG Ming
    2023, 20(03): 834-844.
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    This study compares the strength characteristics of rocks anchored by NPR bolts and ordinary bolts with varied preloads, based on the mechanical properties of NPR bolts(with a negative Poisson's ratio). The results show that the uniaxial compressive stress-strain curve of ordinary anchored rocks exhibits noticeable abrupt changes. After reaching peak strength, the bolt breaks, whereas the stress-strain curve of NPR-anchored rocks is smoother. The NPR bolt enters the stage of continuous resistance after reaching maximal strength and does not break. As the preload increases,the strength of the anchored rock grows linearly. A calculation equation for the strength of the anchored rock is proposed based on the preload. The theoretical equation fits the test results well, and the fitted parameters show that NPR bolts can better increase the strength of the rock. The concept of dynamic toughness UC of anchored rock is proposed to reflect the comprehensive mechanical properties of anchored rock, including strength and plasticity. As the preload increases, the UC of ordinary anchored rock first decreases and then increases, while the UC of the NPR anchored rock does not change significantly with the preload when the strain is small, and the UC increases with the increase of the preload when the strain is large.
  • Shear behavior of two-order morphology in rock joints
    HUANG Man, CHEN Xuan-nan, HONG Chen-jie, LIU Dan, LUO Zhan-you, DU Shi-gui, WU Zao-sheng
    2023, 20(03): 845-858.
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    Two-order morphology of rock joints named as waviness and unevenness can be separated by morphology classification method, which plays a decisive role in the evolution of shear stress during the shear test. The joint morphology is obtained by using 3D printing and 3D laser scanning techniques and the joint model samples in two-order morphology are produced by cement mortar. Then, shear tests are performed under different normal loads. Results shows that the waviness is dominant in the total morphology during the shear test, and the shear contribution of unevenness mainly occurs in the climbing phase of shearing process. Comparing the failure modes of two-order morphology, waviness mainly embodies shear dilation characteristics and unevenness mainly shows shear wear characteristics.Based on this, a quantitative parameter is proposed to represent the ratio of the peak shear strength of the two-order morphology to that of total morphology.The functional relationship between the peak shear strength of total and two-order morphologies is determined, providing a theoretical method for further in-depth study on the shear strength of the interaction with two-order morphology of rock joints.
  • Multi-domain equivalent method for prediction of elastic modulus of complex fractured rock mass
    JIAO Feng-yu, WANG Hui-dong, LI Tuo, CHEN Yun, MA Guo-wei
    2023, 20(03): 859-872.
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    Reliable estimation of deformation and failure behaviors of fractured rock mass is important for practical engineering design. This study proposes a multi-domain equivalent method for fracture network to estimate the deformation properties of complex fractured rock mass. It comprehends both the advantages of the discrete fracture network model and the equivalent continuum model to capture the features of discontinuities explicitly while reducing computational intensity. The complex fracture network is stochastically split into a number of subfracture networks according to the domain, length or angle. An analytical solution is derived to infer theoretically the relationship between the elastic moduli of the original complex fractured rock mass and the split subfractured rock masses by introducing a correction term based on the deformation superposition principle. Numerical simulations are conducted to determine the elastic moduli of split subfractured rock masses using universal distinct element code(UDEC), while the elastic modulus of the original model is estimated based on the currently proposed analytical relationship. The results show that the estimation accuracy with the current domainbased splitting model is far superior compared to those with the other two splitting models. Thus, the estimation method of elastic modulus of complex fractured rock mass based on domain splitting mode of fracture network is identified as the multi-domain equivalent method proposed in this paper. The reliability of this method is evaluated, and its high computational efficiency is demonstrated through exemplification with regard to different geometric configurations for stochastically artificial discrete fracture network. The proposed multi-domain equivalent method constructs the theoretical framework except for the regression analysis hypothesis compared to the density-reduced model equivalent method.
  • Water infiltration and soil-water characteristics of compacted loess under applied vertical stress
    ZHANG Lin, LI Tong-lu, LI Ji-heng, LIANG Wei, CHEN Cun-li
    2023, 20(03): 873-885.
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    Additional stress formed by postconstruction buildings in loess-filling areas affects water infiltration in soil and causes soil deformation.To investigate this effect, under constant water head,vertical infiltration tests on compacted loess with two initial dry densities for different applied vertical stresses were developed using vertical stresscontrollable one-dimensional soil columns. The timehistory curves of vertical deformation, wetting front depth, cumulative infiltration depth, volumetric water content(VWC) and suction were measured, and the soil-water characteristic curves(SWCCs) were determined. The results showed that:(1) the infiltration ability of the soil column weakens with increasing applied vertical stress and initial dry density;(2) vertical deformation increases rapidly at first and then tends to be stable slowly at the consolidation and wetting-induced deformation stage,and is positively correlated with applied vertical stress and is negatively correlated with initial dry density.The stability time of wetting-induced deformation and the corresponding wetting front depth increase with the increase of applied vertical stress, while they decrease obviously when initial dry density increases;(3) the influence of applied vertical stress on soilwater characteristics in soil columns with various initial dry densities is related to the deformation depth of soil column. The VG(Van Genuchten) model is suitable for fitting the SWCCs at different monitoring positions. A normalized SWCC model introducing the applied vertical stress was proposed for each initial dry density using the mathematical relationship between the fitting parameters and the applied vertical stress.