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过刊目录

  • 2021年, 18卷, 第12期
    刊出日期：2024-06-19
      
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  • Alpine ecotone in the Siberian Mountains: vegetation response to warming
    KHARUK Viacheslav I., IM Sergei T., PETROV Il'ya A.
    2021, 18(12): 3099-3108.
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    Birch(Betula tortuosa) is one of the treeline forming species within the Siberian Mountains. We analysed the area dynamics of birch stands and the upslope climb of birch treeline based on the Landsat time series scenes and on-ground data. We found that since the warming onset(1970 th) birch area increased by 10%, birch stands and treeline boundary were moving upslope with a rate of 1.4 m/yr and 4.0 m/yr. Birch upslope shift correlated with air temperatures at the beginning(May-June) and the end(August-October) of the growth period. Meanwhile, no correlation was found between birch upslope migration and precipitation. Winds negatively influenced both birch area growth and birch upslope climb during spring, fall, and wintertime. In the windy habitats, birch, together with larch and Siberian pine, formed clusters(hedges) which mitigated the influence of adverse winds. These clusters are the adaptive pattern for trees' upslope climb within windward slopes. The other adaptation to the harsh alpine ecotone habitat is non-leaf(bark) photosynthesis which supports tree survival. Thereby, Betula tortuosa upslope climb depends on the wind impact and warming in spring and fall that extended growth period. With ongoing warming and observed wind speed decrease on the background of sufficientprecipitation, it is expected to further birch advance into alpine tundra in the Siberian Mountains.
  • Geochemistry of cryoconite and soils in the Central Caucasus region and its environmental implications
    Ivan KUSHNOV, Evgeny ABAKUMOV, Rustam TEMBOTOV, Vyacheslav POLYAKOV
    2021, 18(12): 3109-3124.
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    Climate change and deglaciation are active processes in current changing environments. In the Central Caucasus region rapid degradation of glaciers is caused often by the formation of superficial blackcolored sediments – cryoconite. Cryoconite plays a crucial role in changing ecosystems and may contribute to the formation of primary soils after glacier retreat.Over the past 20 years, the frequency of mudflows and other dangerous mountain events have increased in the Central Caucasus, which is associated with the glacial retreats. Intensification of tourism results in increasing of traffic, recreational activity and environment contamination. Determination of the cryoconites geochemical properties in comparison with other types of sediments and local soils is crucial for investigation of geochemistry and contamination state of superficial glacial sediments. This environmental aspect is important in terms of the Central Caucasus settlements safety under conditions of deglaciation and anthropogenic influence. The sediments studied(cryoconite, mudflow, moraine) were sampled at Garabashi and Skhelda glaciers as well as some local soils at the Baksan gorge. Sampled materials were investigated in terms of physicochemical and agrochemical parameters. The concentrations of trace elements(Cu, Pb, Zn, Ni, Cd) were also determined and contamination indices(geoaccumulation index – I_(geo),contamination factor-CF and degree of contamination – C_(degree)) were used to evaluate the pollution status of studied material. Data obtained shows much higher content of organic carbon in soils(up to 7.82%) in comparison with cryoconite(max. 1.63%) due to presence of vegetation, however, the basal respiration values in some cases were similar between сryoconite and soils, indicating high rates of microbial activity in a cryoconite holes. It was found that almost all materials studied have sandy structure. Cryoconite sediments on both of the glaciers are enriched with phosphorus, high values of K2 O(max. 298 mg·kg~(-1)) and N-NH4(max. 247 mg·kg~(-1)) are identified at Garabashi glacier which could be influenced by long-distant transfer but mostly a result of local anthropogenic activity. In case of trace elements, the highest content is identified for Zn(62 mg·kg-1 for cryoconite and 60.5 mg·kg-1 for soils) and the most contaminated materials are cryoconite from Garabashi glacier and Entisols, up to moderate level,which is mostly associated with local anthropogenic activity.
  • A township-level assessment of forest fragmentation using morphological spatial pattern analysis in Qujing, Yunnan Province, China
    HUANG Xiao-yuan, YE Yuan-hui, ZHANG Zhuo-ya, YE Jiang-xia, GAO Jie, Marc BOGONOVICH, ZHANG Xing
    2021, 18(12): 3125-3137.
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    Forest fragmentation is an integral part of global change. Understanding forest fragmentation patterns and dynamics are of great significance for maintaining ecosystem stability. There are great differences in the interference of natural and human factors on forests in different towns of mountainous cities, and the characteristics of forest fragmentation are also obviously different. Forest fragmentation has been broadly studied, yet, it remains poorly understood at the township-scale within mountainous cities. In this study, the spatial form of forest landscape and forest fragmentation modes of towns were examined in Qujing City, Yunnan Province,China for the years of 2006 and 2016, relying heavily on the morphological spatial pattern analysis(MSPA)and K-means clustering algorithm. Results in 2016 showed that the forest landscape morphology of Qujing could be divided into seven classes: core,perforation, islet, bridge, edge, branch and ring; with landscape areas of 41.94%, 1.22%, 7.04%, 11.12%,23.26%, 11.74% and 3.68% respectively. Compared with 2006, the changes of landscape area were 1.71%,0.02%, 0.30%, 1.65%, 0.20%, 0.19% and 0.05%respectively. The townships in Qujing varied significantly in their landscape fragmentation patterns, and these patterns were spatially dependent.Different forest landscape forms have positive spatial correlations and differences. The forest fragmentation modes of towns can be divided into four types: Low anthropogenic towns, high anthropogenic towns,complex terrain towns and gentle terrain towns.Different ways of human activities play a decisive role in forest landscape fragmentation. The expansion of construction land and agricultural land intensifies forest fragmentation; however, man-made orderly and planned ecological restoration will greatly improve the forest coverage and improve the spatial form of urban forest landscape.
  • Long-term changes of water acidity in an intact forested watershed in south China
    LIU Xiao-dong, FENG Ying-jie, MO Qi-feng, CHU Guo-wei, LI Yue-lin, ZHANG Qian-mei, ZHANG Wei-qiang, GAN Xian-hua, ZHOU Qing
    2021, 18(12): 3138-3146.
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    Acid rain is a global environmental issue and causes serious adverse impacts on natural ecosystems and human health. The acid rain and its subsequent impacts have been extensively studied in temperate regions and in big cities globally, but the monitoring of acid rain in non-urban areas in subtropical region is still limited. Here, we analyze 18 years of water acidity observations from a non-urban site in western Pearl River Delta region, south China.From 2000 to 2018, annual mean precipitation pH values in the study site showed a marked increase(P<0.0001) from 4.96 in 2000 to 6.88 in 2018. This 18-year dataset of precipitation acidity shows a clear recovery from acid deposition over the annual period,dry seasons and wet seasons. Within a year,precipitation p H was relatively lower in dry seasons(5.46±0.95) than in wet seasons(5.80±0.89) during the whole study period, and the seasonal pattern of precipitation pH was amplified during drier years as a strong dilution effect was detected between precipitation amount and its acidity. The pH of surface runoff water(4.74±0.70) was significantly lower than that of precipitation as a result of the regulating effects of the highly acidified soil and the rich humus on the forest floor. The groundwater pH(6.32±0.63) was significantly higher than the precipitation pH especially during dry seasons. The results of the present study indicated that the groundwater has a strong acid buffer and neutralizing effects and thus plays an important role in supplies of clean water.
  • Impact of forcing data and land surface properties on snow simulation in a regional climate model: a case study over the Tianshan Mountains, Central Asia
    LI Qian, YANG Tao, LI Lan-hai
    2021, 18(12): 3147-3164.
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    Snow is a key variable that influences hydrological and climatic cycles. Land surface models employing snow physics-modules can simulate the snow accumulation and ablation processes. However,there are still uncertainties in modeling snow resources over complex terrain such as mountains.This study employed the National Center for Atmospheric Research's Weather Research and Forecasting(WRF) model coupled with the NoahMultiparameterization(Noah-MP) land surface model to run one-year simulations to assess its ability to simulate snow across the Tianshan Mountains. Six tests were conducted based on different reanalysis forcing datasets and different land surface properties.The results indicated that the snow dynamics were reproduced in a snow hydrological year by the WRF/Noah-MP model for all of the tests. The model produced a low bias in snow depth and snow water equivalent(SWE) regardless of the forcing datasets.Additionally, the underestimation of snow depth and SWE could be relatively alleviated by modifying the land cover and vegetation parameters. However, no significant improvement in accuracy was found in the date of snow depth maximum and melt rate. The best performance was achieved using ERA5 with modified land cover and vegetation parameters(mean bias =-4.03 mm and-1.441 mm for snow depth and SWE,respectively). This study highlights the importance of selecting forcing data for snow simulation over the Tianshan Mountains.
  • Runoff variation and its response to climate change in Huolin River catchment, Northeast China
    DAN Dan, CHUN Xi, SHI Lei, XIA Ying-ying, ZHOU Hai-jun, WAN Zhi-qiang
    2021, 18(12): 3165-3178.
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    The Huolin River catchment(HRC) is located in the semi-arid region of Northeast China,which is very sensitive to climate change. The runoff in HRC is closely related to the recovery of local vegetation in the Greater Khingan Mountains and the survival of downstream wetlands. Dramatic runoff fluctuations and increasing no-flow days confirmed the water crisis in this area. Hence, it is extremely urgent to study the current situation and characteristics of runoff. In this study, hydrological and meteorological data of HRC during 1956-2018 were analyzed to elucidate the processes,characteristics, trends of the river runoff and revealed its response to climate change. The Mann-Kendall test and linear regression method showed that runoff in the HRC demonstrated a downward trend over the study period with a marked annual variation. The runoff in the high flow years was 100 times that of the low flow years, showing a typical continental climatic river characteristic. There are two runoff peak flows in the intra-annual runoff distribution in March and July, whereas two runoff valleys occurred around May and September to February. The runoff positively correlates with precipitation in summer and temperature in early spring. Snowmelt influenced by rising temperatures in April and precipitation in July is the main driving factor for the two peaks flow.Evaporation rose with precipitation decline and temperature increased, which may influence the runoff decrease. The annual runoff is well synchronized with the annual precipitation, and precipitation change is the main driving factor of variation and abrupt change points of annual runoff in the catchment. This study would be beneficial for water resource management in developing adaptation strategies to offset the negative impact of climate change in HRC.
  • Influences of environmental factors on the modern ~(14)C reservoir effects in Qinghai-Tibet Plateau lakes
    DU Ding-ding, LI Zhi-wen, HU Hai-ping, BAI Yong-hui, LI Wen, MUGHAL Muhammad Saleem, QIAN Hai-Yan
    2021, 18(12): 3179-3189.
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    The establishment of reliable age in the lake sediment profile mainly depends on the AMS ~(14)C dating technique. However, the presence of the ~(14)C lake reservoir effects(LREs) restricted for using radiocarbon dating in lake sediment, especially in dry and cold areas with a scarce plant cover in the Qinghai-Tibet Plateau. Hence, the discussion of influence factors of LREs is crucial. This paper selected 15 lakes(17 sediment and 3 plant samples) in the Qinghai-Tibet Plateau to examine the distribution characteristics of the modern LREs and their main influencing factors. In our study area, 14 lakes were all affected by the LREs. The minimum ~(14)C year is 5900 a BP towards the deep water area, whereas the maximum ~(14)C year is up to 7185 a BP in the margins of Lake Heihai. The maximum ~(14)C year is up to 7750 a BP, and the minimum ~(14)C year is present-day carbon in the 15 lakes. One further study indicated that the LRE differences in individual lake are mostly owing to the contribution of exogenous carbonate. The results displayed that the LREs tended to increase with the increase of the salinity, moreover, the LREs of saltwater lakes or salt lakes were significantly larger than freshwater lakes due to the possible supply of old total dissolved inorganic carbon with a long residence time in the lakes. Moreover, the contribution of calcite played a significant role on the LREs. Additionally,the LREs differences are affected by the source of organic matter. The lake with groundwater supply shows large LRE due to likely being influenced by crustal and ancient CO2 uprising.
  • Nitrogen absorption by alpine forage species based on ~(15)N tracer technique in a hydroponic culture
    LIU Yan-fang, WANG Wen-ying, MA Xiao-lin, LIU pan, ZHOU Hua-kun, CHEN Zhe, YANG Chong, GUAN Jin-hong
    2021, 18(12): 3190-3199.
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    Based on 15 N tracer technique, absorption of different concentrations of ammonium nitrogen(N-NH4+), nitrate nitrogen(N-NO3-) and glycine(NGly) by root of six species of alpine forage(Puccinellia tenuiflora, Poa crymophila, Festuca sinensis, Elymus nutans, Elymus sibiricus and Bromus inermis) was studied in a hydroponic culture. The uptake kinetic parameter was analyzed according to MichaelisMenten equation. The Michaelis-Menten equation represents the velocity equation for the relationship between the initial rate of an enzymatic reaction and the substrate concentration. The result showed that the absorption range of ammonium nitrogen, nitrate nitrogen and glycine by root of six species of alpine plant were 1.1-20.9 μmol·g~(-1)·h~(-1), 0.4-3.4 μmol·g~(-1)·h~(-1) and 0.1-3.7 μmol·g~(-1)·h~(-1), which accounts for 68.8%-74.7%, 12.0%-27.0% and 4.3%~(-1)3.4% of total absorptivity, respectively. The six kinds of P.tenuiflora, P. crymophila, F. sinensis, E. nutans, E.sibiricus and B. inermis showed significant difference in nitrogen absorption. At the same concentration, the absorption of nitrogen in different forms of the same herbage is different. The absorptive amount of ammonium nitrogen was the highest among them,then the glycine, the nitrate nitrogen was least absorbed. The results could provide a theoretical basis for nitrogen utilization in alpine forages. For example,P. tenuiflora showed a much higher ability of absorbing nitrogen nutrition in a high salt environment and could be a more suitable herbage to be planted in saline-alkali soil in the Qinghai-Tibet Plateau as compared with E. nutans.
  • New application of open source data and Rock Engineering System for debris flow susceptibility analysis
    Sabrina BONETTO, Pietro MOSCA, Federico VAGNON, Davide VIANELLO
    2021, 18(12): 3200-3217.
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    This research describes a quantitative, rapid,and low-cost methodology for debris flow susceptibility evaluation at the basin scale using open-access data and geodatabases. The proposed approach can aid decision makers in land management and territorial planning, by first screening for areas with a higher debris flow susceptibility. Five environmental predisposing factors,namely, bedrock lithology, fracture network, quaternary deposits, slope inclination, and hydrographic network,were selected as independent parameters and their mutual interactions were described and quantified using the Rock Engineering System(RES) methodology. For each parameter, specific indexes were proposed, aiming to provide a final synthetic and representative index of debris flow susceptibility at the basin scale. The methodology was tested in four basins located in the Upper Susa Valley(NW Italian Alps) where debris flow events are the predominant natural hazard. The proposed matrix can represent a useful standardized tool,universally applicable, since it is independent of type and characteristic of the basin.
  • Characteristics of loess landslides triggered by different factors in the Chinese Loess Plateau
    MENG Zhen-jiang, MA Peng-hui, PENG Jian-bing
    2021, 18(12): 3218-3229.
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    Loess landslides are one of the most serious geological disasters in the Chinese Loess Plateau. Research has revealed that earthquake,rainfall, and human activities are common triggers for loess landslides. In order to study the relationship and characteristics of these landslides triggered by different factors, the paper uses historic landslide data to expound the basic motion indices of landslides triggered by different factors. More than half of loess landslides occurred on concave surface slopes, while nearly 40% of the loess landslides occurred on convex surface slopes. Human activities have a great effect on the occurrence of landslides, and the distribution density of landslides on residential land was almost five times that of bare land. Additionally, earthquakeinduced loess landslides had the largest sliding volume, whereas the excavation-induced loess landslide had the smallest sliding volume. The sliding volume of irrigation-induced and rainfall-induced loess landslides were between earthquake-induced loess landslides and excavation-induced loess landslide. Many of loess landslides were induced by a combination of these factors, such as rainfall and excavation, irrigation and excavation. Then a model that described the impact of these factors on the loess landslides was proposed.
  • Field investigations and numerical modeling of a giant landslide in the region of Eastern Himalayan Syntaxis: Jiaobunong landslide
    DU Guo-liang, ZHANG Yong-shuang, YAO Xin, YANG Zhi-hua, YUAN Ying
    2021, 18(12): 3230-3246.
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    Eastern Himalayan Syntaxis(EHS) is a tectonically active region that undergoes continuous geomorphic changes.Large landslides are predominant in this region. A giant landslide called Jiaobunong landslide on the northwestern flank of the EHS were studied and simulated to investigate the formation mechanism, evolutionary process, and failure mechanism of the landside, so that we could better understand the large complex ancient landslides in this region. Field investigation,geological background analyses, and numerical modeling were conducted to reveal the natural and seismic characteristics, as well as dynamic process of the landslide. The results show that the Jiaobunong landslide was the result of long-term geological and geomorphic evolution. Uplift, river incision,weathering, fault creep, glaciation, and earthquakes play key roles in the formation of landslides. Given the huge landslide volume, strong seismicity of the study area, proximity to an active fault, and the need for extra forces to induce landsliding, the Jiaobunong landslide was triggered by a paleo-earthquake. Using numerical simulation based on the discrete element method, the slope dynamic response of the earthquake as well as the mass movement and accumulation process was reproduced. Simulation results showed that the landslide movement experienced four stages: initiation phase(0-5 s),acceleration phase(5-35 s), deceleration phase(35-95 s), and the compaction and self-stabilization stage(after 95 s). The rock mass was disintegrated and experienced strong collisions during the movement.The dammed lake gradually disappeared because of long-term river incision by the overtopping river water. These processes play a vital role in the evolution of landforms in the region of EHS.
  • A combined survey to evaluate the thermal behavior of loess for a landslide-prone slope on the Heifangtai terrace in Northwest China
    ZHANG Hao, ZHANG De-xuan
    2021, 18(12): 3247-3260.
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    A combined survey including infrared thermography(IRT) and field-laboratory tests were conducted to analyze the thermal responses and thermal properties of loess on a landslide-prone loess slope in the Heifangtai terrace in Northwest China aiming at preliminarily demonstrating the potential of IRT as a complementary technique to the investigation of irrigation-induced loess landslides.Multitemporal thermographic surveys corresponding to various solar radiation intensities during the afternoon were carried out on the landslide-prone loess slope. Accordingly, the spatiotemporal distribution of the thermal responses within the observed slope surface was analyzed qualitatively and quantitatively. Meanwhile, field and laboratory investigations were also performed on the thermal properties of different landslide materials. The results indicate that loess, a landslide-prone deposit that usually has a relatively high water content, exhibits different thermal properties and anomalies, including a lower surface temperature and greater thermal inertia, compared to surrounding zones without landslides. The groundwater table and corresponding seepage line could also be obtained by determining the potential boundary between the thermal response distribution of landslide scarps and that of saturated deposits in the presence of landslides. The results of these investigations are expected to provide insight for future endeavors combining infrared thermography with other efficient survey methodologies(e.g., InSAR, which can monitor the active displacement of a loess slope) to evaluate the activity of this kind of excessive irrigation-induced loess landslide.
  • Identification of hidden faults using determining velocity structure profile by spatial autocorrelation method in the west of Mashhad plain(Northeast of Iran)
    Seyedeh Fatemeh NEMATI, Naser HAFEZI MOGHADAS, Gholam Reza LASHKARIPOUR, Hosein SADEGHI
    2021, 18(12): 3261-3274.
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    Characterizing the subsurface structure is an important parameter for the improvement of seismic hazard assessment. Due to the tectonic complexity of the earth, some deep fractures do not reach the earth's surface and are not detectable with visual analysis. Therefore, the lack of knowledge of faults and fractures can result in disasters, especially in urban planning. Many geophysical methods can be used to estimate subsurface structure characterization.However, a more reliable method is required to assess seismic hazards and reduce potential damage in metropolitan areas without destroying buildings and structures. This paper aims to identify hidden faults and structures using shear wave velocity sections. To do this, surface wave dispersion curve was extracted from the vertical component of microtremor array recording using the spatial autocorrelation(SPAC)method in two profiles and 13 array stations(perpendicular to the altitudes) to obtain shear wave velocity structure(Vs) in the west of Mashhad,northeast of Iran. The results of shear wave velocity profiles(Vs) indicate sudden changes in the thickness of sediments. This can be related to the displacement of a normal fault in this area causing the bottom rock to fall and an increase in the alluvial thickness in the central part of the plain. The velocity in the floor rock is 2000 meters per second in this area. According to the surface outcrops and water wells data, its material is slate and Phyllite metamorphic rocks that are exposed in the adjacent heights. Besides, the seismic profile results were well consistent with electrical resistance data and well logs indicating that the tool array method is flexible, non-invasive, relatively fast,and effective for urban areas with satisfactory accuracy.
  • Impact of an artificial chute cutoff on the river morphology and flow structure in Sipaikou area of the Upper Yellow River
    QIAO Qiao, Li Chun-guang, JING He-fang, HUANG Ling-xiao, YANG Cheng
    2021, 18(12): 3275-3290.
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    Artificial chute cutoff can fundamentally eliminate the threat of flood caused by the meandering river, but it significantly changes its morphodynamic characteristics. Channel adjustments after cutoff are rapid, which makes it difficult to study the interaction between river morphology and flow structure only through field measurement. However,numerical simulations can provide insights into the hydrodynamic characteristics after artificial chute cutoffs. In this study, both field measurement and numerical simulation are employed to investigate the flow structure and bed morphology caused by an artificial chute cutoff in Sipaikou area of the Upper Yellow River in 2018. The measured hydrological data provide boundary conditions and initial values for the numerical model. The field measurement results reveal that the concave bank of the study area is severely scoured up to 270 m after the artificial cutoff,and a 20 m deep scour hole and a 2.26 km long pool are formed at the entrance and near the left bank of the chute channel. The numerical simulation results of velocity at typical cross-sections are in good agreement with the measurement results. Flow separation and stagnation zones are observed near the right bank during the low flow conditions(discharge of at least 902 m3/s), but this phenomenon is not seen during larger flow conditions(discharge exceeds 2000 m3/s). Interestingly, flow recirculation zones are also found near the left and right banks of the scour hole. Further, a long flux belt is formed at the scour hole and the pool. Consequently, the impact of the bed topography on the hydrodynamic characteristics is relatively prominent when the discharge is small, while the impact on the river banks and river bed is more noticeable when the water discharge is large. In addition, high shear stress is observed near the left bank at the downstream of the studied area, which indicates that the left bank at the downstream is still being scoured. These results suggest that bank protection measures along the left bank are required to maintain the effectiveness of the artificial chute cutoff.
  • Spatial modeling of solar photovoltaic power plant in Kabul, Afghanistan
    NASERI Mohammad, HUSSAINI Mohammad Salem, IQBAL Mohammad Wasim, JAWADI Hussain Ali, PUYA Marzia
    2021, 18(12): 3291-3305.
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    Energy planning and solar plant site selections are vital strategic decisions and one of the most complex executive challenges in the interconnected procedures. It is essential to study the potential renewable energy sources in Afghanistan to select the most sustainable sites for solar power production in populated cities. This study is based on the combination of a Geographic Information System,Remote sensing, and multi-criteria decision-making technique to evaluate the optimal placement of photovoltaic solar power plants in the Kabul province,capital of Afghanistan. Two models, Analytical Hierarchy Process(AHP) and Analytical Network Process(ANP), were used to select suitable areas for establishing a solar power plant. The application of the proposed model has been made possible by integrating four constraints such as climate,environmental, topography, and economical which comprised twelve criteria: solar radiation, yearly average rainfall, land slope, aspect, land use, dust,geology and proximity to faults, main roads,Normalized difference vegetation index, urban areas river and water bodies. The findings indicate that there is no considerable difference between the results of both models since both models identified more than 20% of the total area of Kabul province in suitable classes. Outputs maps conclude that northern and southern parts of Kabul city and the eastern part of Kabul province came to the range of suitable areas.It can be concluded that Kabul province is a source of sufficient potential for producing solar electricity.The results of this study can support the plans of the Afghanistan government in solar energy production and the implementation of photovoltaic power plants.
  • Women and youths participation in agroforestry: What counts and what doesn't around Mount Elgon, Uganda?
    GALABUZI Charles, AGABA Hillary, OKIA Clement Akias, ODOUL Judith, MUTHURI Catherine
    2021, 18(12): 3306-3320.
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    The increase in global climate change incidents is a glaring indication that more pragmatic and direct approaches to tree and forest management are urgently needed. A study was conducted around Mount Elgon Uganda between June 2018 and December 2019. The objectives were to: i) determine the socio-economic characteristics of women and youth farmers engaged in agroforestry, ii) determine the relationship between women and youth farmers' characteristics in adoption of tree technologies and related decisions, and iii) assess the incentives,challenges and strategies for promoting agroforestry technologies' adoption in the region. Data were collected from 250 women and youths using focus group discussions, semi-structured, and key informant interviews.Results showed that engagements in agroforestry practices attracted largely(82%) of uneducated women and youths and basic methods and tools were used to farm. Up to 70%of women and youth relied on crop farming as a major source of income, earning about USD$ 250 perannum. Farm and family size were positively(P>0.0001) related to tree adoption decisions while farmer capacity building activities(such as training,farmer guided field tours, and participatory farmer trial's establishments) and access to low-cost tree seedlings motivated their involvement in tree planting.Land scarcity, soil, water, and tree conservation issues and shortage of desired tree species affected the extent of tree growing in both women and youth-led households. The suggested strategies comprised strengthening farmer capacity-building programs and upholding soil and water conservation technologies.Agroforestry has the potential to address the challenges related to land scarcity and shortage of desired tree products in women and youth-led households around Mount Elgon. However, the women and youths involved in farming activities were generally poor, illiterate and faced issues of land insecurity. These factors, limited their full potential and interest in agroforestry. A significant increase in tree adoption rates by women and youths will be achieved with increased training on tree seed collection and pre-treatment, reforestation programs as well as tree pest and disease control.
  • Integrated landscape approaches to building resilience and multifunctionality in the Kailash Sacred Landscape, China
    SHI Pei-li, DUAN Cheng, WANG Li, WU Ning, Rajan KOTRU, Janita GURUNG
    2021, 18(12): 3321-3335.
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    Climate warming-induced rangeland degradation in arid and semiarid steppe imposes substantial threats to the livelihoods of people. But this dilemma can be solved by combining all sectors of agriculture, animal husbandry and tourism through their complementarity, i.e. by adopting integrated landscape ecosystem-based approaches. A number of experiences and lessons have been achieved in a specific sector for its successful development, but not in the multiple social, economic, and ecological systems. In this study, we use the perspective of integrated ecosystem management to strengthen crop-livestock integration and innovative livelihoods,and propose a multifunctional Kailash Landscape to activate the inter-linkage among agriculture, animal husbandry, and heritage pilgrimage/tourism in order to achieve multiple functions of the socio-ecological system. A case study of Kailash Sacred Landscape Conservation and Development Initiative in China was quantitatively and qualitatively analyzed by land use and land cover change and their consequences on multiple ecosystem services. Integrated landscape management was found to be effective in building resilience of socio-ecosystems by reducing the vulnerability of traditional agriculture in terms of improving crop production and animal husbandry. A multifunctional landscape is expected to be integrated and build a resilient sector complementarity including farming, pastorism, environmental and socioeconomic function. The analyses show that integrated landscape approaches provide an effective perspective for sustainable socio-economic development in this sacred landscape. The findings highlight the importance of landscape-scale ecosystem-based adaptation to environment change.
  • Comparison of seismic stability for slopes with tensile strength cut-off and cracks
    ZHANG Ying-bin, LIU Yan, YUAN Ran, HE Yi
    2021, 18(12): 3336-3347.
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    The strength of geomaterials is typically predicted by the Mohr-Coulomb yield criterion in slope stability analysis. The tensile strength of soils in this yield criterion, which is an extrapolation of the triaxial compression test results, is usually overestimated. Generally, the influences of tensile stresses in slopes are evaluated by two approaches: 1)introducing cracks to eliminate the tensile stresses in slopes, and 2) truncating the strength envelope to reduce the tensile strength of the soils. However,comparative analyses of the two approaches have not been fully implemented, especially under dynamic conditions. In this study, three slope failure mechanisms corresponding to the predictions of slope stability by the mentioned two approaches subjected to seismic loadings are systematically evaluated. The stability factor considering the pre-existing crack,crack formation, and tension cut-off are compared one another. The most unfavorable crack locations corresponding to the different mechanisms are evaluated. The influence of tensile strength on the factor of safety of slopes is estimated as well. Further,the critical acceleration and the permanent displacement of slopes with pre-existing crack, and tension cut-off are derived in the framework of the kinematic theorem of limit analysis. The vertical effects of seismic coefficient on critical acceleration and permanent displacement are discussed.Conclusions can be drawn that the consideration of tension zone effects can sharply reduce the stability factor of slopes, especially for steep slopes and large horizontal seismic loads; different from the static condition, the slope with pre-existing crack is not always the most vulnerable to collapse, the tension cut-off mechanism in steep slopes may predict the lowest stability factor. In addition, the calculation shows that an evidently increase in the slope displacement is induced by the increasing downward vertical loads, while a decrease occurs if the vertical loads are upward.
  • Numerical investigation on the fatigue failure characteristics of waterbearing sandstone under cyclic loading
    ZHU Chun, HE Man-chao, JIANG Bei, QIN Xin-zhan, YIN Qian, ZHOU Yu
    2021, 18(12): 3348-3365.
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    The strength of sandstone decreases significantly with higher water content attributing to softening effects. This scenario can pose a severe threat to the stability of reservoirs of pumped storage power stations developed from abandoned mines,especially when subjected to the cyclic loading condition caused by the repeated drainage and storage of water(fatigue damage). Based on this, it is essential to focus on the fatigue failure characteristics.In this study, the mineral composition of the used sandstone of Ruineng coal mine in Shanxi Province,China, was first tested to elucidate the rock softening mechanism after absorbing water. Next, a numerical model for replicating the mechanical behavior of water-bearing sandstone was established using twodimensional particle flow code(PFC2 D) with a novel contact model. Then, 16 uniaxial cyclic loading simulations with distinct loading parameters related to reservoir conditions(loading frequency, amplitude level, and maximum stress level) and different water contents were conducted. The numerical results show that all these three loading parameters affect the failure characteristics of sandstone, including irreversible strain, damage evolution, strain behavior,and fatigue life. The influence degree of these three parameters on failure behavior increases in the order of maximum stress level, loading frequency, and amplitude level. However, for the samples with different water contents, their failure characteristics are similar under the same loading conditions.Furthermore, the failure mode is almost unaffected by the loading parameters, while the water content plays a significant role and causing the transformation from the tensile splitting with low water content to the shear failure with higher water content.
  • Individual and combined influences of main loading parameters on granite damage development under ultrasonic vibration
    ZHANG Cheng, ZHAO Da-jun, ZHANG Shu-lei, ZHOU Yu
    2021, 18(12): 3366-3379.
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    Ultrasonic vibration technology has great potential to weaken hard rocks. Understanding the effect of ultrasonic vibration loading parameters is essential to accelerate the application of this technology in practical rock engineering. In the present work, three-factor mixed-level orthogonal ultrasonic vibration rock breaking tests were conducted to investigate the influence of the main loading parameters, including confining pressure,vibration frequency, and static force, on the damage of granite specimens. The individual and combined influences were analyzed according to the porosity increase and P-wave decrease of granite specimens using the variance analysis method. The results show that the combined effect of the static force and vibration frequency mainly promotes fatigue damage of specimens, that the confining pressure determines the damage behaviour and failure mode of specimens under ultrasonic vibration, and that the confining pressure and vibration frequency are the main factors that cause the fracture concentration in the upper part of specimens, an effect mechanistically driven by the obvious load energy attenuation. The research results provide theoretical guidance for the application of ultrasonic vibration technology.