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过刊目录

  • 2022年, 19卷, 第04期
    刊出日期：2024-06-19
      
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  • Tourist boom and rural revival-Case study of K?odzko Region(SW Poland)
    SZMYTKIE Robert, LATOCHA Agnieszka, SIKORSKI Dominik, TOMCZAK Przemys?aw, KAJDANEK Katarzyna, MIODO?SKA Paulina
    2022, 19(04): 909-924.
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    Rural areas in the K?odzko Region were subject to a long-term depopulation, marginalization,and long-lasting socio-economic decline since the 19th century. In recent years, however, the study area has been subject to a shift in socio-economic trends that show rural revival. The main goal of the research is to assess the actual role of tourism in socio-economic revival of rural areas in the K?odzko Region. To determine the dynamics of the tourism function development, statistical data were used and an inventory of tourism beds in accommodation facilities was conducted. The results show that there was a substantial development of the tourism function in the study area and its most intense scale was noted in the depopulating villages, as evidenced by the increase in the numbers of tourism facilities and numbers of tourism beds. Therefore, it can be concluded that the development of tourism contributed to the limitation of negative socioeconomic processes in the area and, in the case of some villages, even to the reversal of these trends,which might testify to the rural revival. Moreover, the improvement of the socio-economic situation is visible also in the villages that do not have significant tourist values but are in the neighbourhood of tourism hotspots. This observation might be important for forecasting future development and planning of rural areas.
  • Spatially-explicit quantitative relationship for a potential PES mechanism:Cascade hydropower development in Yarlung Zangbo River Basin, China
    ZHU Xiao-kang, FU Bin, Ramon Felipe BICUDO DA SILVA, GUO Ying-man, QIN Chan-yuan, FENG Ting, YU Hai-bing, XIAO Kuang
    2022, 19(04): 925-944.
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    Payment for ecosystem services(PES) is of great importance for the sustainable development of mountain areas, key hotspot regions for the provisioning of ecosystem services. At present, PES researches mainly focus on forest protection, carbon sink trading, and water protection. As an important industry in mountainous areas, cascade hydropower development has generated substantial economic benefits accompanied by social and ecological impacts. However, efficient PES mechanisms to deal with hydropower generation in mountain areas are still unavailable. Therefore, the lacking of PES in mountain systems limits the development of those areas, and compromise the sustainability of hydropower development. The critical reason lies in the lack of a scientific method that can quantitatively analyze the relationship of hydropower stations with a geographical scope at county level(i.e., quantifying the water yield service provided by each county within the cascade hydropower development basin), and with different hydropower enterprises. We use the Yarlung Zangbo River Basin of China as case study area, one of the major hydropower development basins in China. First, we used Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model to map water yield service. Then, we calculated the value of water yield service by relating the water yield to the gross output value of hydropower stations. We revealed the relationship(e.g., hydropower stations and identified counties) between the payers and the payees of ecosystem services through mapping and quantifying the provisioning regions in the supply of water yield service and the users(hydropower enterprises). Finally, we discussed the current situation of benefit distribution in cascade hydropower development basin based on the supply and use of the water yield service. The results showed that 1) the spatial distribution of the value of water yield service is uneven: the upper reaches are highvalue areas; the eastern region is higher than the western region; and the maximum value(USD 119.2$/km2) is 34 times higher than the minimum value(USD 3.5 $/km2). 2) We found that four state-owned enterprises are the direct beneficiaries of water yield service, and 37 counties are suppliers, among which Gongbogyamda, Lhari and Damxung are the first level of supply. 3) Each hydropower station is provided with water yield service by several counties, and the value of water yield service varies greatly in each county, showing spatial differences. 4) Most counties are only partially involved in the process of water yield service being used by hydropower stations(i.e.,the boundary of water yield service is inconsistent with the administrative boundary). 5) Huaneng Tibet Yarlung Zangbo River Hydropower Development and Investment Co., Ltd. gets the greatest value(USD 1.8million $) from the use of water yield service, while China Energy Tibet Electric Power Co., Ltd. gets the smallest(USD 389.1 thousand $). 6) Counties near the lower reaches have gained more economic benefits, while the water yield service they provide have the lowest contribution to hydropower production. Our approach linked water yield ecosystem service and hydropower development effectively, and revealed their complex eco-economic relationship between producers and beneficiaries of ecosystem services, which provides key insights for the designing of a potential PES mechanism.
  • Effects of conservation measures on crop diversity and their implications for climate-resilient livelihoods: the case of Rupa Lake Watershed in Nepal
    BAI Yun-li, FU Chao, THAPA Balaram, RANA Ram Bahadur, ZHANG Lin-xiu
    2022, 19(04): 945-957.
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    Agrobiodiversity conservation is vital for achieving sustainability, but empirical studies on the effects of different practices or measures on crop diversity are rare. This study aims to estimate the effects of raising conservation awareness(RCA),building diversity blocks(BDB), and their combination on crop diversity among 240 randomly selected households surrounding the Rupa Lake Watershed in Nepal. Based on descriptive analysis and multiple regression models, the results indicate that the two single measures had no significant effect on the numbers of crop species and varieties grown by households in 2018. However, the combination of RCA and BDB had a significantly positive effect on the number of crop varieties, especially for grain and vegetable crops. Considering that these crops are essential in the daily lives of local people, the results indicate that a strategy that combines both awareness raising and on-farm conservation measures can generate higher crop diversity and better serve the climate-resilient livelihoods of people in mountainous areas.
  • Influence of social capital on the livelihood strategies of farmers under China's rural revitalization strategy in poor mountain areas: A case study of the Liangshan Yi autonomous prefecture
    HE Ren-wei, GUO Shi-li, DENG Xian, ZHOU Kui
    2022, 19(04): 958-973.
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    Social capital in the form of social resources or social networks is one of the most important livelihood capital of farmers, which can increase the labor productivity of poor households and increase income. It is important to explore the reasons underlying the livelihood strategy choices of farmers from the perspective of social capital under China's rural revitalization strategy. In this study, the Liangshan Yi Autonomous Prefecture, a povertystricken mountainous area in southwestern China, was selected as the case study area, and multivariable linear regression models were constructed to analyze the influence of social capital on livelihood strategies.The results are as follows:(1) Individual social capital had a positive effect on non-agricultural livelihood strategies. On average, with a one-unit increase in individual social capital, the ratio of farmers' nonagricultural income to total productive income(Income＿Rto) increased by 0.002% and 0.062%,respectively. Collective social capital, with the Peasant Economic Cooperation Organization(PECO) as the carrier, had a negative effect on the non-agricultural livelihood strategies of farmers; on average, with a oneunit increase in PECO, Income＿Rto decreased by approximately 0.053%. However, this effect was only significant in the river valley area.(2) The income differences among the different livelihood strategy types were explained by the livelihood strategy choices of farmers. As non-agricultural work can bring more benefits, the labor force exhibited one-way migration from villages to cities, resulting in a lack of the subject of rural revitalization. It is necessary to implement effective measures to highlight the role of PECO in increasing agricultural income for farmers. Finally,based on the above conclusions,policy recommendations with respect to livelihood transformation of farmers and rural sustainable development are discussed.
  • Effect of the Grain for Green Project on freshwater ecosystem services under drought stress
    HAN Hui-qing, YANG Jian-qiang, LIU Yue, ZHANG Ying-jia, WANG Jun-wen
    2022, 19(04): 974-986.
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    The Grain for Green Project(GGP) is an important measure for the prevention of sloping farmland and the restoration of natural vegetation.This project has been critical to the restoration of ecological environments in western China. However,the effect of the GGP on freshwater ecosystem services under extreme climates remains unclear. Thus, taking the middle and upper reaches of the Wujiang River Basin in western China as an example, this study assessed the variation of three freshwater ecosystem services(e.g., water yield, soil retention and nutrient retention) impacted by the GGP under drought stress by employing the Integrated Valuation of Ecosystem Services and Tradeoffs(In VEST) model. In addition,the trade-off/synergistic relationship between three freshwater ecosystem services was analyzed based on the Pearson correlation coefficient. As revealed from the results, the effect of the GGP on the water yield and nutrient retention under drought stress was significantly higher than that on the soil retention.With the increase in the drought degree, the variation rate of the water yield and nutrient retention impacted by the GGP increased, whereas that of the soil retention decreased. The GGP in droughts of different seasons resulted in a significant heterogeneity in the changes of three freshwater ecosystem services. The correlation coefficients between the water yield and soil retention as well as that between the water yield and the nutrient retention increased, and the correlation coefficients declined between soil and nutrient retention under different drought degrees following the GGP. Unlike for the summer drought case, there were no significant changes in the correlation coefficients between three freshwater ecosystem services in spring, autumn and winter droughts. The results suggest that the amount of farmland converted to shrubland should be regulated to reduce the trade-off intensity between freshwater ecosystem services. In addition, food security and ecological environment protection should be balanced during the implementation of the GGP, and the most concentrated distribution region of farmland-to-forest conversion will be the key area of ecological management in the future.
  • GIS-based spatial differentiation of ethnic minority villages in Guizhou Province, China
    ZHENG Guang-hui, JIANG Di-fei, LUAN Yong-fei, YAO Yao
    2022, 19(04): 987-1000.
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    The protection and development problems in ethnic minority villages have received great attention from the Chinese government. This study aims to systematically identify the spatial differentiation characteristics of ethnic minority villages and their influencing factors in Guizhou Province. Applying ArcGIS and GeoDa, a total of 1,014 ethnic minority villages in the four batches announced by the Ethnic and Religious Affairs Commission of Guizhou Province(272in the first batch, 240 in the second batch, 255 in the third batch, and 247 in the fourth batch) served as the research objects. Utilizing the economic development data in Guizhou Statistical Yearbook 2018-2020 for analysis, the coupling calculation of the spatial layout and economic development level of ethnic minority villages was conducted. The results indicate that the number of ethnic minority village points varies in spatial distribution with remarkable agglomeration. The spatial equilibrium distribution of ethnic minority villages in the province is imbalanced. The kernel density is characterized by independent single kernel centers with sporadic distributions of subcenters and an echelon distribution whole. The spatial complexity distribution indicates that ethnic minority villages in Guizhou possess unequal characteristics, and the fractal of the system structure is more complicated. The findings reveal that the spatial distribution of ethnic minority characteristic villages in Guizhou is highly consistent with that of ethnic minorities in Guizhou. The distribution is the combined results of geographical factors and socialeconomic factors. Most ethnic minority characteristic villages in Guizhou Province are located in areas with complex terrain, inconvenient transportation, and relatively backward economic development. Based on the current geospatial distribution of ethnic minority villages,the present study will provide remarkable implications for the Chinese government to implement the Rural Revitalization Strategy from several key aspects. The Chinese government should establish a protection and development mechanism in ethnic minority villages and strive to enhance the characteristics of ethnic cultural industries. Meanwhile, the "integration of culture and tourism" should be taken as the development strategy while the industry should support rural economic development and help eliminate poverty. This is of crucial practical significance to national unity and rural revitalization in China.
  • Depth-resolved numerical model of dam break mud flows with Herschel-Bulkley rheology
    TANG Jin-bo, LIN Peng-zhi, CUI Peng
    2022, 19(04): 1001-1017.
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    Mud flows are common phenomena in mountainous areas, which can threaten human safety and cause property losses under certain extreme circumstances. Studying the dynamic characteristics of mud flows, especially in the vertical direction, is helpful for risk reduction and hazard mitigation. In this study, a 2D depth-resolved numerical model based on Herschel-Bulkley rheology was developed to study the vertical structures of unsteady mud flows with a free-surface. The numerical model was solved by the projection method, and the free surface of mud flows was captured through the VOF method. To fully validate this new model, a series of laboratory experiments involving dam break mud flows were conducted, and the mud flow heights, bottom pressures and envelopes of mud residuum were measured. The numerical model proposed in this study was first validated by the steady-state solution for uniform flows of Herschel-Bulkley fluid on an inclined plane. Additionally, the simulated and measured mud flow heights, bottom pressures at different x locations and envelopes with different bed slopes showed good agreement. Furthermore, the numerical results for a Herschel-Bulkley fluid dam break flow were used to validate the proposed model,which further revealed good agreements. After that,the scenarios in which mud flows impact on a structure were numerically studied, and the vertical profiles of the front velocity and impact pressure on the structure were analyzed and discussed. The results show that a plug layer was formed in the mud flow under unsteady and nonuniform flow conditions,and the impact pressure on the structure was dominated by the dynamic pressure. In addition, the vertical position with the maximum impact pressure acting on the structure was not at the bottom or the surface of the mud flows, and the normalized vertical position rose as the yield stress and consistency coefficient increase for Herschel-Bulkley fluids.
  • Landslide susceptibility mapping using the infinite slope, SHALSTAB,SINMAP, and TRIGRS models in Serra do Mar, Brazil
    Thiago Machado do PINHO, Oswaldo AUGUSTO FILHO
    2022, 19(04): 1018-1036.
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    Slope failure triggered by heavy rainfall is very common in tropical and subtropical regions and a cause of major social and economic damage.Landslide susceptibility maps can be generated using geographical information systems(GIS) and limit equilibrium slope stability models coupled or not to hydrological equations. This study investigated the efficacy of four models used for slope stability analysis in predicting landslide-susceptible areas in a GIS environment. The selected models are the infinite slope, the shallow slope stability model(SHALSTAB),the stability index mapping(SINMAP), and the transient rainfall infiltration and grid-based regional slope-stability(TRIGRS). For comparisons, the authors(a) included the infinite slope equation in all models,(b) clearly defined input parameters and failure triggering mechanisms for each simulation(soil depth, water table height, rainfall intensity),(c)determined appropriate values for each model to obtain stability levels that represented similar hydrogeotechnical conditions, and(d) considered upper-third areas of landslide scars to estimate the reliability of susceptibility maps using validation indices. An intense rainfall event occurred in Serra do Mar, Brazil in January 2014 triggered hundreds of landslides and was used for back analysis and evaluation of the slope stability analysis models.When rainfall intensity is not considered, the four models produced very similar results. The most reliable landslide susceptibility map was generated using TRIGRS and considering the granite residual granite soils geological-geotechnical unit, subjected to a rainfall intensity of 210 mm for 2 h under unsaturated conditions.
  • Model test study on the formation and development of underground erosion ground fissures in the Kenya Rift Valley
    LIU Yang, PENG Jian-bing, JIANG Fu-qiang, LU Quan-zhong, ZHU Feng-ji, Xu Qiang
    2022, 19(04): 1037-1050.
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    The Kenya Rift Valley is relatively prone to underground erosion ground fissures and associated disasters, which gravely hinder local engineering construction and economic development. In this research, we performed field and experimental studies on ground fissures in the Kenya Rift Valley area, and determined the structural characteristics of underground erosion fissures. Based on a geological survey of the area, we generalized a geological model for typical ground fissures and reproduced the intermediate process of ground fissure propagation using a large-scale physical model test. Further, the development process of underground erosion fissures were categorized into four stages: uniform infiltration,preferential infiltration, cavity expansion, and collapse formation stages. During the development of underground erosion fissures, water content was distributed symmetrically along the fissures, and these fissures acted as the primary infiltration paths of water. When the ground collapsed, the increase in negative pore water pressure was greater, whereas the increase in positive pore water pressure was less in the shallow soil; moreover, in the deep soil, the increase in positive pore water pressure was greater than that of negative pore water pressure.Additionally, the earth pressure increment initially increased and then decreased with the development of erosion. During underground erosion collapse, the water content and pore water pressure appeared to increase and decrease rapidly. These results can be employed to predict the occurrence of underground erosion ground fissures and the resulting soil collapse.
  • Numerical investigation of rock dynamic fragmentation during rockslides using a coupled 3D FEM-DEM method
    LIU Yang, WENG Lei, CHU Zhao-fei
    2022, 19(04): 1051-1069.
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    Rockslides are one of the most common geological hazards in mountainous areas and can pose significant threats to the safety of human lives and infrastructures. Studying the dynamic fragmentation process, and fragment characteristics of rock blocks during rockslides is of great significance. In this study,the influences of the slope angle on the dynamic fragmentation process, damage and energy evolution,and the fragments' flying velocity and flying angle were systematically investigated using a coupled 3D FEM-DEM method. An improved fragment search algorithm was first proposed to more effectively extract the information of the fragments after impacting. The input parameters in the numerical modeling were carefully calibrated based on the quasi-static uniaxial compression tests and the rockimpact tests. The complex fragmentation process of rock block sliding along an inclined slope was simulated. The results indicate that the fragmentation intensity gradually increases with increasing the slope angle, and the fragmentation intensity of the front region of the rock block is always higher than that of the rear region. Additionally, the slope angle can significantly affect the damage ratio, energy dissipation, and the ratio of tensile crack to shear crack during the rockslides. The number of the fragments having higher flying velocities and larger flying angles increases with increasing the slope angle,which contributes to a larger spreading distance and a wider deposition area.
  • Reconstructed annual glacier surface mass balance in the ányêmaqên Mountains, Yellow River source, based on snow line altitude
    LI Kai-ji, CAO Bo, GUAN Wei-jin, PAN Bao-tian, SHANGGUAN Dong-hui
    2022, 19(04): 1070-1081.
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    Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources. In this study, we analyzed the changes in glacier area, snow line altitude(SLA) and surface elevation in the ányêmaqên Mountain region using multisource remote sensing data. Then, the annual mass balance of two glaciers was reconstructed by using SLA-mass-balance gradient method. The results showed that the glacier area in the ányêmaqên Mountains decreased by 29.4 km2from 1985 to 2017. The average SLAs of the Halong Glacier and Yehelong Glacier were approximately 5290 m and 5188 m, respectively. The glacier mass balance for the two glaciers from 1990 to 2020 was-0.71 m w.e. a-1 and-0.63 m w.e. a-1, respectively. Our results indicate that SLA is an important indicator of glacier changes, and a long sequence of SLAs can more accurately reconstruct the glacier mass balance of the glacier. The mean annual glacial meltwater-fed streamflow is 1.45 × 10~7 m~3 and 1.12 × 10~7 m~3,respectively. Sensitivity analysis indicates that summer air temperature plays a leading role in regard to the influential climatic factors of glacial retreat in the ányêmaqên Mountains. This highlights the potential of the methodology for application on reconstructing annual glacier surface mass balance at larger scales without direct measurements.
  • Comparative analysis of the mass elevation effect and its implication for the treeline between the Tibetan and Bolivian plateaus based on solar radiation
    YAO Yong-hui, SUO Nan-dong-zhu, ZHANG Yi-chi
    2022, 19(04): 1082-1094.
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    As one of the main non-zonal factors, the mass elevation effect(MEE) has significant impacts on both regional climates and mountain ecological patterns. In recent years, with the development of quantitative techniques and methods, quantitative studies on the MEE and its implication on mountain altitudinal belts have developed rapidly. However,some issues have not been solved yet, such as high errors in spatial temperature estimations and difficulties in the definition and extraction of intramountain base elevation. Moreover, there is still a lack of comparative studies on the MEE and its influence on treelines and snowlines as most studies were conducted on specific mountains or plateaus. To compare the MEE magnitudes of the Tibetan Plateau(TP) and the Bolivian Plateau(BP), we estimated the correspondent air temperatures and simulated the solar radiations based on MODIS surface temperature,station observation, and treeline data. Then, we analyzed the elevation of the 10°C isotherms on the two plateaus, the temperatures at the same elevation,and the solar radiations. According to the mechanism of the MEE and the relationship of solar radiation and treeline, we constructed treeline models for the two plateaus through a stepwise regression analysis by considering several influencing factors of the MEE(e.g., air temperature and precipitation) and using solar radiation as its proxy. The results showed that:(1) the MEE magnitude on the TP is equivalent to that on the BP although the former is slightly higher than the latter;(2) the MEE strongly influences the highest treelines in the northern and southern hemispheres,which both occur on the two plateaus. Notably, the treeline distribution models based on solar radiation had higher accuracies than those models with parameters of temperature and precipitation(the adjusted R2 values were 0.76 for the TP and 0.936 for the BP), indicating that solar radiation can be used to quantify the MEE and its implications on treelines.Overall, the results of this study can serve as a basis for subsequent analyses on the MEE's impact factors.
  • Morphologic changes of simple star dunes during the growth process in Dunhuang, China
    AN Zhi-shan, ZHANG Ke-cun, TAN Li-hai, NIU Qing-he, LIU Ben-li, NIU Bai-cheng
    2022, 19(04): 1095-1106.
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    Star dune is one typical kind of aeolian geomorphology in global sand seas. It has attracted scholars in various research fields for years because of its unique morphologic features like Egyptian pyramid.The landform pattern of star dune is mainly dominated by factors such as regional wind regime, sand availability, and local topography. Star dunes grow vertically as they accumulate sand brought in from different directions; however, little is known regarding morphologic changes during this process. The stability of star dunes based on quantitative data is another unsolved question due to the limitation in measuring equipment or other factors. And whether the star dune can grow into star sand hills is another scientific problem which needs to be discussed. In this paper, the heightening development process and morphological changes of star dunes were monitored in Mingsha Mountain of Dunhuang with the 3D laser scanner.Results show that the star dunes in Mingsha Mountain were formed by a group of relatively steady winds,which were northwest, northeast and south winds. With the increase of the height of the star dunes, the morphological parameters of the dune, such as the volume and bottom area, did not show regular changes.The surface erosion of both Dune 1 and Dune 2 during the observation period was closely related to the regional wind conditions. During the growth of the star dunes, the overall trend of the dunes was relatively steady and the dune shape maintained its stability although the aspect and slope of the sand dunes changed, indicating that the stability of star dune was not complete and was dynamic. Moreover, the variation range of the dune slope was proportional to the volume change of the dune.
  • Atmospheric deposition fluxes and health risk assessment of potentially toxic elements in Caohai Lake(Guizhou Province, China)
    LIN Shao-xia, ZHANG Zhuan-ling, XIAO Zhi-qiang, LIU Xiao-lan, ZHANG Qing-hai
    2022, 19(04): 1107-1118.
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    In this study, the sources of potentially toxic elements(PTEs) from atmospheric deposition in the waters of Guizhou's Caohai Lake were investigated in addition to the potential risks to human health.Moss bags were used to enrich PTEs from atmospheric deposition, and eight monitoring sites that best represented geographic variation were established around Caohai Lake. Moss bags were collected and examined at every 3 months to identify spatiotemporal patterns of dry and wet atmospheric deposition of PTEs. Zn was the most abundant metal identified from deposition in Caohai(72.07%–95.94%), followed by Pb and Cd, while Hg was the least abundant(0.008%–0.354%). The contributions of wet deposition of PTEs were greater than those of dry deposition, and deposition during the heating season from December to April was greater than that between April to July. Hg was mainly derived from atmospheric dry deposition(65.38%–84.44%).Spatial distribution analysis indicated that atmospheric deposition was associated with the intensity of human activities and heating emissions.Exposure via hand-to-mouth contact accounted for over 99% of the total exposure risk although overall exposure was lower than threshold acceptable levels for carcinogenic and non-carcinogenic metals,indicating an overall lack of risk towards human health. Nevertheless, the health risk from atmospheric deposition of PTEs in Caohai Lake may be reduced by focusing on Zn, Pb, and Cd deposition in rainfall and minimizing the hazards associated with hand-to-mouth exposure to PTEs.
  • Assessing sediment connectivity and its spatial response on land use using two flow direction algorithms in the catchment on the Chinese Loess Plateau
    YAN Xi-qin, JIAO Ju-ying, TANG Bing-zhe, LIANG Yue, WANG Zhi-jie
    2022, 19(04): 1119-1138.
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    Severe soil and water loss have led to widespread land degradation on the Loess Plateau in China. Exploring the relationship between land use and sediment connectivity can be beneficial to control soil erosion. In this study, three catchments in the Yanhe River Basin on the Loess Plateau were selected to analyse the relationship between land use and sediment connectivity using grey correlation method.Index of connectivity(IC) was employed to quantify sediment connectivity, including two flow direction algorithms(D8 and D-infinity) and two final targets of sediment transport(outlet and main channel of catchment). Then, 11 landscape metrics were used to evaluate the land use spatial patterns of catchments.By comparing the IC value ranges, histograms and classes, and their relationship with remote sensing images of the two flow direction algorithms, we find that the D8 algorithm is more suitable for this study area. The results showed that the three catchments are characterized by high sediment connectivity in the grassland and forest close to the channel. In addition,the roads and bare land close to the channel also have high or medium sediment connectivity. Grey correlation analysis showed that landscape division index(DIVISION), fractal dimension index(FRACMN), aggregation index(AI), total class area, patch cohesion index(COHESION), and largest patch index(LPI) indices were the main factors that affect sediment connectivity at the class scale. At the landscape scale, the landscape shape index(LSI),Shannon's diversity index(SHDI), and gully density have an essential effect on sediment connectivity. This condition provides a way to control the sediment connectivity in the watershed by transforming land use type or changing its spatial pattern, but specific adjustment measures have to be further explored.
  • Effect of altitude and climatic parameters on shrub-meadow community composition and diversity in the dry valley region of the eastern Hengduan Mountains, China
    ZONG Hua, SUN Jia-rui, ZHOU Lu, BAO Fang, ZHENG Xian-zhu
    2022, 19(04): 1139-1155.
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    Because of the “foehn effect”, deeply incised gorges of major rivers in the Hengduan Mountains(commonly called dry valleys) have semiarid or arid climate. Harsh environment and difficult access have so far obstructed the systematic inventory and documentation of the flora of these dry valleys. This is particularly problematic for efforts towards the conservation of endemic and valuable plant species. Therefore, 102 shrub-meadow community survey plots were set up along four dry valleys in Ganzi prefecture, located in the eastern Hengduan Mountains, China. The compositions,richness, diversity of these communities were calculated and assessed using sample plot survey and phytosociological approach. Overall, 244 plant species were recorded, consisting of subtropical(48.77%) and temperate(38.83%) species, 47.13% of which were endemic to southwest China. Obvious differences in species composition and structure along the altitude gradient were observed. The variations of richness,diversity, and evenness followed a bimodal-hump shaped pattern with increasing altitude, with peak occurring at mid-level altitude(3501–4000 m) and valley occurring at 2501–3000 m altitude. The regions at 2501–3000 m altitudes were more sensitive to global climate change and biological interference, and were found to have the highest protection value. The impacts of altitude gradients and climatic parameters on the features of this shrubmeadow community were also evaluated using principal component and multiple linear stepwise regression analysis methods.Altitude and temperature-related variables were the most important drivers of both species richness and cover.Species α-diversity here only depended on the precipitation frequency. This founding could help to understand the impact of the very harsh environment and altitude gradient on plant-plant interactions in a variety of natural systems.
  • Short-term effects of yak and Tibetan sheep urine deposition on soil carbon and nitrogen concentrations in an alpine steppe of the northern Tibetan Plateau, China
    DU Zi-yin, WANG Xiao-dan, CAI Yan-jiang
    2022, 19(04): 1156-1167.
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    Yak(Bos grunniens) and Tibetan sheep urine deposited onto the alpine grasslands of the Qinghai-Tibetan Plateau is an important pathway for nutrient return, and it is closely related to soil fertility and alpine grassland productivity. However, hitherto, few studies have reported the effects of yak and Tibetan sheep urine deposition on soil carbon(C) and nitrogen(N) concentrations and the possible functional mechanisms under field conditions in alpine grasslands. To explore the status of soil C and N responding to the immediate N addition from livestock urine, we conducted a 28-d field experiment with three treatments, which include the application of yak urine(YU) and Tibetan sheep urine(TSU) application, and the control(CK, no application of urine). The results showed that YU treatment increased the soil moisture content and p H at 0-10 cm across the 28-day experimental period. Urine application resulted in the fluctuation of soil organic C(SOC) and increased topsoil SOC concentration during the middle and later periods of the experiment. Application of YU evidently increased the soil total N(TN) concentration in the 0-10 cm layer, while it did not affect the SOC concentrations in the 10-20 and 20-30 cm layers. Compared with the control, YU treatment significantly(P<0.05) increased the 0-10 and 10-20 cm soil ammonium-N(NH_4~+-N) concentration throughout the 28 days, while the TSU treatment significantly(P<0.05) increased the 0-10 and 10-20 cm soil nitrate-N(NO_3~--N) concentration. Urine N input changed soil physicochemical properties, nitrification, denitrification, and N leaching processes, and therefore affected the availability of N accumulation and consumption in soil. Under these conditions, the trade-off between soil NH_4~+-N and NO_3~--N under the influence of yak and Tibetan sheep urine application would change the form and concentration of available N, thereby altering the plant N uptake and utilization strategy of alpine grassland. The conclusions of this study could provide theoretical references for exploring the change characteristics of soil nutrient under the deposition of urine and optimizing the management strategies of livestock urine in the alpine grassland ecosystem.
  • Unraveling the distribution patterns of near-surface temperature lapse rates in the Northwestern Kunlun Mountains
    SUN Cong-jian, CHEN Wei, SHEN Yan-jun
    2022, 19(04): 1168-1181.
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    The near-surface temperature lapse rates for the core area of the Kunlun Mountains remain critically unresolved due to data scarcity. Here, we revealed the spatial and temporal patterns of nearsurface temperature lapse rate in the Kunlun Mountain regions based on both long-term meteorological records(1961-2017) and field surveys measured data(2012-2017). The results showed that(1) The near-surface temperature lapse rates(β_(local))has spatiotemporal distribution patterns on the Northwestern Kunlun Mountains(NWKM), and in complex terrain areas the complexity of the temperature-elevation relationship cannot be explained by the constant environmental temperature lapse rate(0.65°C/100 m) throughout alone.(2) The β_(local) for the daily mean, minimum, and maximum temperature on the north slopes in the Kunlun mountain area are 0.41, 0.47, and 0.37°C/100 m and on the Tiznafu River(TR) basin are 0.51, 0.47 and 0.53°C/100 m, respectively.(3) The variations of β_(local) for daily maximum and minimum temperature of the two regions exhibit similar monthly characteristics,which are lower in the winter and spring months than in other months. A greatest variability of β_(local) for the daily mean, minimum, and maximum temperature appears in winter and a light variability of β_(local) occurs in spring. The seasonal variability of β_(local) for daily maximum temperature is greater than that for daily minimum temperature, and the seasonal variability of β_(local) for daily average temperature has the smallest variability.(4) There is no significant trend of change occurred in the β_(local) of NWKM.(5) The spatial and temporal variations of β_(local) for the NWKM are linked to the geographic differences and climate factors. The results of Grey Relational Analysis showed that the β_(local) distribution is mainly influenced by the wind speed and relative humidity of the NWKM.
  • Two-and three-dimensional stability analysis of underground storage caverns in soft rock(Cappadocia, Turkey) by finite element method
    SARI Mehmet
    2022, 19(04): 1182-1202.
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    Engineering design in soft rocks and its stability analysis exerts many challenges to rock engineers. Many engineering works in Turkey's Cappadocia region must face and tackle the existing sites covered by the soft rocks. This study is aimed to examine the stability condition of a typical underground storage cavern(USC) excavated in a soft rock in this region. For this purpose, two-and threedimensional stability analyses of the USCs were performed using the finite element method(FEM).Because of the inherent difficulty in characterizing soft/weak rock masses in the region using traditional classification systems, the stability of a typical USC was evaluated by representing the rock mass condition with two distinct scenarios in FEM analysis.While these structures were unstable according to the 2D analysis conducted in RS2 software in the worstcase scenario, they were stable in the 3D analysis using RS3 software in both scenarios. Besides,feasible cover depths were examined to assess their possible effects on the factor of safety and deformation measurements. It was found that 15 m seems to be an optimal depth for excavating a typical USC in the soft rocks exposed in the region. The 3D FEM results provide valuable information to optimize the future planning and preliminary design of USCs.
  • An evaluation method for internal erosion potential of gravelly soil based on particle size distribution
    ZHU Qin, SU Li-jun, LIU Zhen-yu, WANG Bin
    2022, 19(04): 1203-1214.
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    Internal erosion occurs when fine particles escape from the soil driven by seepage flow, which is considered to be the crucial factor causing the failure of earth structures filled with gravelly soil. The objective of this paper is to suggest an appropriate method to assess internal erosion potential of gravelly soil. By analyzing the sensitivity of soil material to internal erosion, the variable(Dc15/df85)max and the content of coarse particles(Pc) are selected as the evaluation indexes(Dc15 and df85 are the diameters of 15% mass passing in the coarse component and 85%mass passing in the fine component, respectively). A series of gravelly soils with different particle size distributions are tested for internal erosion by the self-made permeameter. Based on the test results, an evaluation method for the internal erosion of gravelly soil is proposed. Gravelly soil is prone to internal erosion when 60% ≤ Pc < 95% and(Dc15/df85)max ≥ 9.5.The proposed method shows good accuracy in evaluating the internal erosion of 36 soil samples from other studies, which confirms the reliability of the method. The proposed method makes it possible to accurately assess internal erosion of gravelly soil,and an alternative method is provided for engineers to determine whether there is a risk of internal erosion in earth structures consisting of gravelly soil.