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Abstract: The impacts of vegetation restoration on the soil erosion have been widely elucidated in the semi-arid regions. However, the magnitude of soil erosion on abandoned sloping farmland still remained unclear and their responses to vegetation succession were rarely addressed. The main objective of this study is to determine the magnitude of soil erosion along vegetation succession and explore the impact of vegetation succession on soil erosion from abandoned sloping farmland. Field observations were employed to monitor the rainfall, runoff, and soil erosion of seven sloping farmland plots with different abandoned ages and bare land from 2015 to 2019. The results indicated that the annual runoff depth and soil erosion modulus of vegetation types were in the range of 0.46 to 5.49 mm·a−1 and 1.3 to 24.5 t·km−2·a−1, respectively. The vegetation effectively reduced the annual surface runoff and soil erosion with reduction of 73.8% to 97.8% and 98.0% to 99.9% as opposed to bare land. However, there were no significant differences in runoff and soil erosion for different vegetation types along succession. The largest event of vegetation types contributed to 38.7%–44.1% of the annual runoff and 42.5%–66.3% of the annual soil erosion, respectively. Vegetation restoration considerably alleviated the contribution of largest erosive event to annual soil erosion. The relationships between soil erosion, runoff and rainfall factors could be fitted well by linear functions, and the performances of regression models in predicting runoff were more satisfactory compared to in predicting soil erosion. The Artemisia gmelinii (Agm) + Stipa bungeana (Sb) optimized the trade-off between sediment reduction and runoff maintenance, which should be selected as a suitable vegetation type to achieve the sustainability of socio-ecological systems. PubDate: 2022-05-11
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Abstract: Land cover change in the semi-arid environment of the eastern Hindu Kush region is driven by anthropogenic activities and environmental change impacts. Natural hazards, such as floods presumably influenced by climatic change, cause abrupt change of land cover. So far, little research has been conducted to investigate the spatiotemporal aspects of this abrupt change in the valleys. In order to explore the abrupt change in land cover and floods as its possible drivers in the eastern Hindu Kush, a semi-arid mountain region characterized by complex terrain, vegetation variation, and precipitation seasonality, we analyzed long-term Landsat image time series from 1988 to 2020 using Breaks For Additive Seasonal and Trend (BFAST). Overall, BFAST effectively detected abrupt change by using Landsat-derived Modified Soil Adjusted Vegetation Index (MSAVI). The results of our study indicate that approximately 95% of the study area experienced at least one abrupt change during 1988–2020. The years 1991, 1995, 1998, 2007, and 2016 were detected as the peak years, with the peaks occurring in different seasons. The annual trend of abrupt change is decreasing for the study area. The seasonality of abrupt change at the catchment level shows an increasing trend in the spring season for the southern catchments of Panjkora and Swat. The spatial distribution patterns show that abrupt change is primarily concentrated in the floodplains indicating that flooding is the primary driver of the land cover change in the region. We also demonstrated the accurate detection of past flood events (2015) based on the two case examples of Ayun, Rumbur, and Kalash valleys. The detection of the flood events was verified by fieldwork and historical high-resolution Google Earth imagery. Finally, our study provides an example of applying Landsat time series in a dry mountain region to detect abrupt changes in land cover and analyze impact of natural hazards such as floods. PubDate: 2022-05-11
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Abstract: This study highlights the influence of freezing-thawing processes on soil erosion in an alpine mine restoration area. Accordingly, a series of simulation experiments were conducted to investigate runoff, sediment, and nutrient losses, and potential influencing factors under freeze-thaw (FT) conditions. Three FT treatments (i.e., 0, 3, and 5 FT cycles), and two soil moisture contents (SMCs; i.e., 10% and 20% SMC on a gravimetric basis) were assessed. The runoff, sediment yield, ammonia nitrogen (AN), nitrate nitrogen (NN), total phosphorus (TP), and dissolved phosphorus (DP) losses from runoff were characterized under different rainfall durations. The fitting results indicated that the runoff rate and sediment rate, AN, NN, TP, and DP concentrations in runoff could be described by exponential functions. FT action increased the total runoff volume and sediment yield by 14.6%–26.0% and 8.8%–35.2%, respectively. The runoff rate and sediment rate increased rapidly with the increment of FT cycles before stabilizing. At 20% SMC, the total runoff volume and sediment yield were significantly higher than those at 10% SMC. The loss curves of AN and NN concentrations varied due to differences in their chemical properties. FT action and high SMC promoted AN and NN losses, whereas the FT cycles had little effect. FT action increased TP and DP losses by 60.2%–220.1% and 48.4%–129.8%, respectively, compared to cases with no FT action; the highest TP and DP losses were recorded at 20% SMC. This study provides a deep understanding of freezing-thawing mechanisms in the soils of alpine mine restoration areas and the influencing factors of these mechanisms on soil erosion, thereby supporting the development of erosion prevention and control measures in alpine mine restoration areas. PubDate: 2022-05-11
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Abstract: On August 30, 2020, a high-intensity storm that dropped 45.4 mm of rain in 5 hours hit the Heixiluo basin and triggered a landslide-generated debris flow event, causing fatalities and damage. The original source of the debris flow was a large slope collapse on a steep hillside. The fallen debris mass was enlarged through sediment entrainment and slope collapse and ultimately buried a bridge at the gully entrance. Approximately 6.9×105 m3 of material, including sediments and collapsed slope deposits in the gullies, was entrained, and the maximum erosion depth reached 17 m. A geomorphological analysis was initially performed based on a detailed field investigation to recognize the liquid and solid sources of the debris flow and the areas subjected to deposition and erosion. A map of the erosiondeposition distribution was obtained based on pre-and post-event DEMs. Using the rainfall estimated by the nearest rain gauge and the solid source estimated by the DEMs, runoff and debris flow propagation was simulated using a liquid-solid two-phase model that considers the effects of runoff and entrainment. The similarity between the estimated and simulated deposition-erosion volumes was satisfactory. The behaviour of debris flows captured in the simulation is broadly in line with the main features of the observed event. PubDate: 2022-05-11
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Abstract: The design of remediation works for the mitigation and prevention of the associated risk is needed where these geological hazards affect anthropized areas. Remedial measures for landslides commonly include slope reshaping, plumbing, drainage, retaining structures and internal slope reinforcement, while debris flow control works consist in open or closed control structures. The effectiveness of the remedial works implemented must be assessed by evaluating the reduction of the risk over time. The choice of the most appropriate and cost-effective intervention must consider the type of hazard and environmental issues, and selects, wherever possible, naturalistic engineering operations that are consequently implemented according to the environmental regulations or the design and specification standards imposed by the competent public administrations. The mitigation procedures consist of five basic steps: (a) acquisition of the knowledge of the hazard process; (b) risk assessment with identification of possible disaster scenarios; (c) planning and designing of specific remedial measures to reduce and/or eliminate the potential risk; (d) slope monitoring after application of remedial measures, (e) transfer of knowledge to the stakeholders. This paper presents two case studies describing the practice for the design of the mitigation measures adopted for debris flow and active landslide sites in North-Eastern Italy. The first case study is a debris flow site, for which, based on observation of past events and numerical simulations using the software FLOW-2D, the most suitable mitigation measures were found to be the construction of a debris basin, barriers and breakers. The second case study deals with an active landslide threatening a village. Based on the landslide kinematics and the results of numerical simulations performed with the code FLAC, hard engineering remedial works were planned to reduce the driving forces with benching and by increasing the available resisting forces using jet grout piles and deep drainage. PubDate: 2022-05-11
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Abstract: Environmental changes significantly alter the structure, diversity and activity of soil microbial communities during spring freezing-thawing period, leading to changes in the soil microbial nitrogen cycle. Changes in N2O fluxes after land use conversion from primary forest to secondary forest, Korean pine plantation and cropland in northeast China have not been quantified. Field experiments were conducted to measure soil N2O fluxes in a primary forest, two secondary forests, a Korean pine plantation, and one maize field in a temperate region in northeast China from 2017-03-06 to 2017-05-28. During the experimental period, the soil was exclusively a nitrogen source for all land uses. We found that N2O emissions ranged from 15.63 to 68.74 µg m−2 h−1, and cumulative N2O emissions ranged from 0.33 to 2.10 kg ha−1 during the period. Cumulative N2O emissions from the maize field were significantly higher than that from primary forest, Korean pine plantation, hardwood forest, and Betula platyphylla forest by 262.1% to 536.4%. Compared with other ecosystems in similar studies, the N2O emission rates of all ecosystem types in this study were low during the spring thaw period. Stepwise multiple linear regression indicated that there were significant correlations between N2O emissions and environmental factors (air temperature and soil temperature, soil water content, soil pH, NH4+−N, NO3−−N, and soil organic carbon). The results showed that conversion of land use from primary forest to hardwood forest, Korean pine plantation or maize field greatly increased soil N2O emissions during spring freezing-thawing period, and N2O emissions from primary forest were almost the same as those from Betula platyphylla forest. PubDate: 2022-05-11
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Abstract: Abstract This paper presents a generalized dilatancy angle equation of granular soil to cover not only the drained tests but also the undrained tests by introducing a generalized structure of soil: soil skeleton formed by soil particles and the fluid in soil voids, under the assumptions of the incompressibility of soil particles and the compressibility of the fluid in soil voids. For the drained tests, the generalized dilatancy angle equation of granular soil would be degenerated to its current dilatancy angle equation. However, for the undrained tests, the generalized dilatancy angle equation of granular soil was derived with a λ parameter that was related to the stress-strain state of soil and the nature of the fluid in soil voids. The λ parameter was determined by the initial dilatancy angles of granular soil at the onset of shearing on the same initial state of the soil in the drained and undrained tests. In addition, the generalized dilatancy angle equation of granular soil was verified for application in calculation of the dilatancy angles of sands in the drained and undrained tests. PubDate: 2022-05-01
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Abstract: Abstract Groundwater contamination has been on the rise in Afghanistan. It has become a major concern among the policy makers. This paper aims to propose practical options for the management of nitrate contamination in one of Afghanistan’s groundwater polluted provinces, Kabul. The management framework utilized Mann-Kendall and Sen Slope tests to detect nitrate trend and geostatistical analysis option in ArcGIS 10.5 to assess the nitrate change. To explore the impact of various management options, a number of legislative documents were reviewed. The results indicate a decline in the nitrate storage of Kabul aquifers from 108 mg/L in 2005 to 0.044 mg/L in 2010. Considering the whole period of the study, the results show that the nitrate volumes remain lower than the nitrate concentration range proposed by World Health Organization (50 mg/L). Groundwater dynamics in Kabul aquifers were influenced by nitrate derived from precipitation and nitrate input from root zones in agricultural areas. Finally, different management options for groundwater pollution from nitrate and corresponding authorities, incorporated urban, rural and agriculture, were proposed. It is expected that this study will help policy makers to better manage the nitrate storage of Kabul aquifers by implementing the proposed management options. PubDate: 2022-05-01
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Abstract: Abstract There is a strong link between vegetation and environmental factors. Therefore, to elucidate how the stoichiometric characteristics of plants respond to different habitats, we studied organic carbon (C) and total nitrogen (N) stoichiometry characteristics of plants in four different habitats of two different natural Korean pine forests. Three of the habitats (gaps, mounds, and pits) were formed via tree uprooting, whereas an undisturbed site (closed canopies) was used as a control. The followings were our main findings: (1) the organic carbon content of more than half of the 12 picked plants showed significant differences in different habitats. Most of the plants in pit-mound complexes exhibited lower organic carbon contents than plants in gaps and closed canopies; (2) there was no significant differences in the total nitrogen content in 13 of the 25 groups of plant samples; (3) interestingly, the C/N of the sample groups with significant differences in total nitrogen also showed significant differences; (4) there was no significant variations in the stoichiometric characteristics of plants that grew in gaps; however, the variations among plants that grew in pits and mounds were significant; (5) through redundancy analysis (RDA), we find that the main factors effecting the C and N stoichiometric characters of the plants were plants own regulation and the change of photosynthetically active radiation (PAR). In conclusion, the C and N stoichiometric characteristics of plants did not respond to gap formations, but they did strongly respond to pit-mound complex formations. Photosynthetically active radiation was the most important effective factor to plants in the four habitats. PubDate: 2022-05-01
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Abstract: Abstract Smallholder livelihoods in agricultural areas in Tibet Autonomous Region, China (Tibet for short) have traditionally been based on subsistence mixed crop-livestock systems. Like many parts of China and the developing world, rural Tibet is undergoing rapid change in agricultural development, boosted by links with the off-farm sector. However, the agricultural transition process in Tibet has not been linear, is affected by policies particular to the region, and varies significantly for different categories of rural actors. This paper analyses heterogeneity of household types in agricultural areas of southern Tibet and how household structures and characteristics result in different agricultural development pathways. Data is drawn from a stratified random survey of 144 households in three townships in southern Tibet and analysed through three methods: cluster analysis, bio-economic modelling, and analysis of household perceptions and attitudes to change. The analysis allows for the identification of three key household types — semi-subsistence, pluriactive and semi-commercial — organised along a continuum of intensification, commercialisation, specialisation and productivity. The study demonstrates the diversity of household farming systems in Tibet which in turn highlights the need for disaggregated analysis and tailored development policies and strategies. However, the analysis also reveals commonalities in development paths between groups, where all farm types are more interested in pursuing income and livelihood goals through an increase in productivity than through an increase in scale. Farmers in all systems choose to retain agriculture as a base from which to pursue livelihood strategies, especially through off-farm activities. Accounting for this household heterogeneity is important on several levels. First, it provides more granular detail on the process of development in rural areas of Tibet that have been very difficult to access in English literature especially in recent years. Second, the characteristics of the case study in agricultural areas of Tibet — especially the mixed agricultural-pastoral systems, high levels of seasonality, heavy state investment and increased integration with the other regions of China — may contribute to the broader agricultural development study. Third, policymakers in the central and local governments may be interested in how the household heterogeneity may affect — or be affected by — policies to increase agricultural productivity, intensify systems, change the composition of crop-livestock systems, promote rural-urban transformation and pursue environmental objectives, especially grassland degradation. PubDate: 2022-05-01
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Abstract: Abstract Despite the continuous advancements of engineering construction in high-intensity areas, many engineering landslides are still manufactured with huge thrust force, and double-row piles are effective to control such large landslides. In this study, large shaking table test were performed to test and obtain multi-attribute seismic data such as feature image, acceleration, and dynamic soil pressure. Through the feature image processing analysis, the deformation characteristics for the slope reinforced by double-row piles were revealed. By analyzing the acceleration and the dynamic soil pressure time domain, the spatial dynamic response characteristics were revealed. Using Fast Fourier Transform and half-power bandwidth, the damping ratio of acceleration and dynamic soil pressure was obtained. Following that, the Seism Signal was used to calculate the spectral displacement of the accelerations to obtain the regional differences of spectral displacement. The results showed that the overall deformation mechanism of the slope originates from tension failure in the soil mass. The platform at the back of the slope was caused by seismic subsidence, and the peak acceleration ratio was positively correlated with the relative pile heights. The dynamic soil pressure of the front row piles showed an inverted “K”-shaped distribution, but that of the back row piles showed an “S”-shaped distribution. The predominant frequency of acceleration was 2.16 Hz, and the main frequency band was 0.7–6.87 Hz; for dynamic soil pressure, the two parameters became 1.15 Hz and 0.5–6.59 Hz, respectively. In conclusion, dynamic soil pressure was more sensitive to dampening effects than acceleration. Besides, compared to acceleration, dynamic soil pressure exhibited larger loss factors and lower resonance peaks. Finally, back row pile heads were highly sensitive to spectral displacement compared to front row pile heads. These findings may be of reference value for future seismic designs of double-row piles. PubDate: 2022-05-01
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Abstract: Abstract Geochemical differentiation of soils has a series of consequences on plant and places pressure on the ecological environment. The quantitative evaluation of element migration in the Earth’s critical zone is a challenging task. In this study, two demonstration study areas of Scutellaria baicalensis Georgi were selected, and multiple chemical weathering indexes, chemical loss fraction, mass migration coefficients and biological enrichment coefficient method were used to assess the ecological and geochemical suitability. The results show that for the element of Fe, Zn, Se, Cu, Co, Ni, Mo and Ge, the degree of weathering and soil maturation, were greater in the rhyolitic tuff area than in the Plagioclase gneiss area. In both research sites, the heavy metal level of samples in Scutellaria baicalensis Georgi did not exceed the standard limits. The plagioclase gneiss region’s surface soil environment was more alkaline, and the content of soil organic matter was lower, resulting in a higher bioenrichment intensity of Ge, Co, Cu, and Se elements in Scutellaria baicalensis Georgi than in the rhyolite-tuff area. The elements of Cd, Nb, Mo, Pb and As are considerably enriched in the soil of the plagioclase gneiss area but lost by leaching in the soil of the rhyolite tuff area, which is connected to the interplay of elemental abundance and human impact in the parent materials. This study provides a good example of how to assess growth suitability of Chinese medicinal materials in the Earth’s critical zone. PubDate: 2022-05-01
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Abstract: Abstract Investigating the interrelation between snow and vegetation is essential to explain the response of alpine ecosystems to climate change. Based on the MOD10A1 daily cloud-free snow product and MOD13A1 NDVI (normalized difference vegetation index) data, this study analysed the spatial and temporal patterns of snow phenology including snow onset date, snow end date, snow cover days, and vegetation phenology including the start of growing season, the end of growing season and the length of growing season in the Chinese Tianshan Mountainous Region (CTMR) from 2002 to 2018, and then investigated the snow phenological effects on the vegetation phenology among different ecogeographic zones and diverse vegetation types. The results indicated that snow onset date was earlier at higher elevations and later at lower elevations, while snow end date showed opposite spatial distribution characteristics. The end of growing season occurred later on the northwest slope of the CTMR and the Yili Valley. The earliest end of growing season was in the middle part of the CTMR. A long growing season was mainly distributed along the northern slope and the Yili Valley, while a short growing season was concentrated in the middle part of the CTMR. The response of vegetation phenology to changes in snow phenology varied among vegetation types and ecogeographic zones. The effect of snow phenology on vegetation phenology was more significant in IID5 (Yili Valley) than in the other ecogeographic zones. A negative correlation was observed between the start of growing season and snow end date in nearly 54.78% of the study area, while a positive correlation was observed between the start of growing season and the snow end date in 66.85% of the study area. The sensitivity of vegetation phenology to changes in snow cover varied among different vegetation types. Snow onset date had the greatest effect on the start of growing season in the four vegetation cover types (alpine meadows, alpine steppes, shrubs, and alpine sparse vegetation), whereas the snow cover days had the least impact. Snow end date had the greatest impact on the end of growing season in the alpine steppes and shrub areas. The study results are helpful for understanding the vegetation dynamics under ongoing climate change, and can benefit vegetation management and pasture development in the CTMR. PubDate: 2022-05-01
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Abstract: Abstract Pyramid cut blasting is an essential form of inclined hole cut blasting, but the in-situ stress effect of pyramid cut blasting is rarely studied. Based on the research background of pyramid cut blasting in a deep rock mass, the size, volume, and fragment size distribution of the blasting cavity before and after uniaxial compression were analysed by a model test. Otherwise, the damage and effective stress of the pyramid cut blasting were analysed with LS-DYNA numerical simulation. The results show that the damage and fragmentation of pyramid cut blasting are not only affected by blasting stress wave and blasting gas, but also affected by uniaxial compression. Under the influence of uniaxial compression, the blasting stress wave and blasting gas are more likely to damage the rock mass parallel to the uniaxial compression direction near the connecting line of blasting hole, and make the volume of cavity larger and the fragment rate lower. Additionally, uniaxial compression has a prominent influence during the middle and late stages of blasting. PubDate: 2022-05-01
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Abstract: Abstract Atomizing rainfall caused by flood discharge of high dams poses a great threat to the safety of powerhouse and ecological environment. As an indispensable means, numerical calculation is widely used in the safety design of discharge structures. The distribution of rainfall intensity is closely related to the trajectory nappe shape, jet trajectory distances, the splashed water droplet diameter and its velocity, and the spatial distribution of downstream nappe wind. In this paper, an experimental result is used to verify the improved stochastic splash mathematical model under different bucket types and discharge conditions, and the sensitivity of downstream rainfall intensity distribution to the shape of trajectory nappe, discharge flow, spatial distribution of downstream nappe wind, and the corresponding relationship between the droplet diameter and its splashing velocity is analyzed. The results show that the calculation accuracy of downstream rainfall intensity distribution is significantly improved when the above factors are taken into consideration. It is found that the bucket type and flood discharge rate play the greatest role in the rainfall intensity distribution, followed by the downstream nappe wind distribution, and finally the corresponding relationship between the diameter and velocity of splash droplets. Therefore, these factors should be considered comprehensively when the rainfall intensity distribution of flood discharge atomization is calculated. This study can help us to understand the influence factors of flood discharge atomization more deeply and predict the distribution of flood discharge atomization rainfall intensity more accurately. PubDate: 2022-05-01
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Abstract: Abstract The Transantarctic Mountains are an important corridor between the East Antarctic Ice Sheet and the Western Ross Sea, where most current ice streams and outlet glaciers arise. We investigated Ricker Hills, the largest exposed mountainous region between Southern Victoria Land and Terra Nova Bay, and dated the glacial landforms using in-situ cosmogenic-nuclide 10Be surface exposure dating to reconstruct the paleo-glacial dynamics. The surface of the Hollingsworth glacier lowered since the middle of Marine Isotope Stage (MIS) 2 (22.1 ka); therefore, the Last Glacial Maximum (LGM) occurred before that period. Cosmogenic, geomorphic, and climatic records constrained the glacial surface slope to be between 5.4° and 6.8°. The ice was 270–320 m thicker at the LGM (MIS 2) than presently but did not override the top surface of the Benson Knob. Moreover, previous glacial periods such as the local LGM (MIS 4) or Penultimate Glacial Maximum (MIS 6) maintained thicker ice than the LGM (MIS 2). The Ross Ice Shelf opening during the mid-Holocene (∼6 ka) caused the rapid collapse of the terminal outlet glaciers and supplied notable snow accumulation upstream, which stagnated lowering. The greatest lowering and retreat occurred during the late Holocene (2.3 ∼ 0.8 ka), when elephant seal colonies thrived in the Ross Embayment. PubDate: 2022-05-01
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Abstract: Abstract To explore the water table and water inflow after tunnel excavation in a vertically stratified phreatic aquifer, approximate analytical solutions for the steady-state water table and water inflow of a drained tunnel in a vertically stratified phreatic aquifer were obtained based on the Dupuit assumptions and the integral method. By comparing the approximate analytical solutions with numerical solutions, it was found that the relative error of the approximate analytical solution for the water table elevation is less than 10%, and the relative error of the approximate analytical solution for the water inflow is approximately 25%. The sources of the above errors are as follows: ① At the lateral boundary of water replenishment, the water surface should be tangent to the horizontal line, but the water surface for the approximate analytical solutions has a gradient. ② At the vertical boundaries near the tunnel, the total head is variable, but the total head for the approximate analytical solutions is assumed to be constant. ③ The Dupuit assumptions are applied in the flow domain near the tunnel. Although the relative errors of the approximate analytical solutions for the water table elevation and water inflow are evident, the lowered water table is reflected in the approximate analytical solutions. PubDate: 2022-05-01
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Abstract: Abstract The development of erosive landforms such as rills, ditches, slits, and gullies depends on many environmental factors; thus, the rate of the development of each individual form differs. In this paper, the author presents a case study of two erosion rills located on a hiking trails (Holy Cross Mts.) resulting after 2 years of monitoring in which the process of their evolution was precisely analyzed. Once established, such landforms develop over time with variable rates and can represent multiple different stages. Moreover, the final result of the rill development hardly reminds their original form and does not allow for interpretation of the events that affected it in the recent past. Therefore, the main objective was to determine the volumetric changes of erosion rills created by the surface runoff on both sections, during two years of observation. Additional objectives included a description of the physical and meteorological parameters, important in the development process and a comparison of them to the volumetric changes of each period. Using the Structure-from-motion (SfM) photogrammetry technique, monitoring procedures have been performed quickly offering sufficient accuracy. For direct comparison, the digital elevation model of difference (DoD) method was used, enabling the calculation of volume. The results showed that the erosion to deposition ratio was more disproportionate during storm events or periods with higher depth of rainfall. Total erosion to deposition balance for the entire monitoring period was negative and equal to 1448.84 kg or 410 Mg/ha for the first erosion rill and 1059.5 kg or 300 Mg/ha for the second rill. Both erosion rills developed differently. The first erosion rill developed by linear cut into deeper and wider form, while the other, steeper rill, evolved from plunge pools merging together into deeper and wider form. PubDate: 2022-05-01
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Abstract: Abstract Climate is a key factor to determine the pattern of ecosystems; however, the latitudinal patterns of climatic variables in the arid and semi-arid areas remain largely unclear when compared to humid areas. The topography of the dry valleys of southwestern China plays an important role in the formation of climate. However, its impact on the climate remains qualitative. In this study, eight climatic variables from 12 meteorological stations were analyzed to explore their latitudinal patterns in the wet and dry seasons from 1961 to 2019. We also quantified the effects of local topography (RH10) on the climatic variables. The results were as follows: sunshine duration, total solar radiation, average temperature, and evaporation decreased significantly, and wind speed increased significantly with increasing latitude in the annual, wet, and dry seasons (P<0.001). Relative humidity and precipitation decreased significantly with increasing latitude in the wet season (P<0.001), and no obvious change pattern was observed in the dry season. Aridity index significantly decreased (toward dryness) with increasing latitude in the wet season and increased in the dry season (P<0.001). Wind speed had a significantly positive relationship with topography (RH10) (P<0.01), whereas precipitation and aridity index were negatively associated with topography in the wet season and positively associated with topography in the dry season. Dryness was positively associated with RH10 in the wet season, and negatively in the dry season. The results of our research could provide new perspectives for understanding the relationship between topography and drought in the dry valleys of southwestern China. PubDate: 2022-05-01
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Abstract: Abstract Since the first impoundment of the Three Gorges Reservoir (TGR) in China in 2003, more than 5000 landslides including potential landslides were identified. In this paper, a deep-seated active landslide in TGR area was analyzed. Fourteen years’ monitoring data and field investigations from 2006 to 2020 were used to analyze the deformation characteristics, influencing factors, and meteohydrological thresholds. The landslide showed a none-overall periodic movement pattern featuring acceleration during long-duration rainfall and rapid transition to constant creep after rainfall events. Two secondary sliding masses, No. 1 and No. 2, were defined via field investigation. The reservoir has no impact on the deformation whereas long-duration-low-intensity rainfall is the main factor. At present, the cumulative displacements of the main sliding mass range from 0.9 to 3.2 m, and the deformation during the rainy season is gradually increasing. The boundary of this landslide was formed, and the boundary of No. 2 sliding mass became obvious. The probability of the failure of sliding mass No. 2 is very high under the conditions of continuous rainfall. The 15-day antecedent rainfall combined with 4-day cumulative rainfall could be the rainfall threshold which could be associated with the groundwater level S1 of 294 m above sea level for forecasting large deformation of Tanjiawan landslide. PubDate: 2022-05-01
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