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Assessment of SoilGrids data for soil erosion estimation at watershed scale: A case study in northern Thailand

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Pedosphere 2024年第4期34卷 797-813页

作者： Chike Onyeka mADUEkE Dhruba Pikha shrestha Panagiotis NYkTAS Department of Natural Resources Faculty of Geo-information Science and Earth Observation(ITC)University of TwenteEnschede 7500 AEthe Netherlands Department of Applied Earth Sciences Faculty of Geo-information Science and Earth Observation(ITC)University of TwenteEnschede 7500 AEthe Netherlands Department of Soil Science and Land Resources management Nnamdi Azikiwe UniversityP.M.B.5025AwkaAnambra State 420110Nigeria

Soil erosion has been identified as one of the most destructive forms of land degradation,posing a threat to the sustainability of global economic,social and environmental *** underscores the need for sustainable land management that takes erosion control and prevention into *** requires the use of state-of-the-art erosion prediction *** models often require extensive input of detailed spatial and temporal data,some of which are not readily available in many developing countries,particularly detailed soil *** soil dataset Global Gridded Soil Information(SoilGrids)could potentially fill the data ***,its value and accuracy for soil erosion modelling in the humid tropics is still unknown,necessitating the need to assess its value vis-à-vis field-based *** major objective of this study was to conduct a comparative assessment of the value of SoilGrids and field-based soil data for estimating soil *** samples were collected from five physiographic positions(summit,shoulder,back slope,foot slope,and toe slope)using the soil catena *** were collected using a 5-cm steel sample ring(undisturbed)and a spade(disturbed).Data of the landform,predominant vegetation types,canopy cover,average plant height,land use,soil depth,shear strength,and soil color were recorded for each *** soil samples were subjected to laboratory analysis for saturated hydraulic conductivity,bulk density,particle size distribution,and organic matter *** functions were applied on the SoilGrids and field-based data to generate soil hydrological *** resultant field-based data were compared with the SoilGrids data for corresponding points/areas to determine the potential similarities of the two *** datasets were then used as inputs for soil erosion assessment using the revised morgan-morgan-Finney *** results from both datasets were again compared to determine the degree of *** r

关键词： hillslope modelling pedotransfer function similarity assessment soil erosion modelling soil loss soil survey

Investigating low dispersion isotope dissolution Lu-Hf garnet dates via in situ Lu-Hf geochronology,kanchenjunga Himal

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Geoscience Frontiers 2024年第3期15卷 137-145页

作者： kyle P.Larson John m.Cottle mark Button Brendan Dyck Iva Lihter Sudip shrestha Department of Earth Environmental and Geographic SciencesUniversity of British ColumbiaOkanaganKelownaCanada Department of Earth Science University of CaliforniaSanta BarbaraUSA Fipke Laboratory for Trace Element Research University of British ColumbiaOkanaganKelownaCanada

Re-examination of three specimens from the kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth *** analyses from grain cores in two specimens define Paleozoic regressions whereas analyses from grain rims in the same specimens define low-precision regressions consistent with the timing of Himalayan *** dates contrast with previously published low dispersion,ca.290 ma isotope dissolution(ID)Lu-Hf garnet dates for the same *** of Lu and spot age distribution in representative grains from the specimens examined yields calculated dates that approximate the Permian-age regressions through the original ID *** findings demonstrate that it is possible to generate low dispersion ID Lu-Hf data from multigenerational garnet with significantly different-age growth events when approximately equal proportions of the different age reservoirs are included in multi-component aliquots.

关键词： Lu-Hf geochronology In situ Lu-Hf geochronology kanchenjunga Himal

Impacts of road on plant invasions in the middle mountain region of central Nepal

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Journal of mountain Science 2024年第2期21卷 619-632页

作者： Ananda ADHIkARI Adarsha SUBEDI Achyut TIWARI Bharat Babu shrestha Central Department of Botany Tribhuvan UniversityKirtipur 44618Nepal

Biological invasion is triggered by human development activities such as the construction and expansion of road *** verges serve as important habitats and corridors for the distribution of invasive alien plant species(IAPS)between geographically distant ***,the trajectory of plant invasion and the data regarding the impact of roads on IAPS distribution are relatively poor in ***,we surveyed two road types(main roads and feeder road)in the middle mountain region of central Nepal in order to investigate how different road types are driving the dispersal of IAPS along road verges and the adjacent natural *** sampling was conducted at ca 2.5 km intervals along the *** each sampling site,paired plots(25 m×4 m)were sampled:one adjacent to and along the road,and another 20 m away and parallel to it in the interior *** results revealed that the main road verges had a higher cover(33%)and a larger number of IAPS(14 species)than the feeder road(25%;10 species).The IAPS cover and richness were significantly higher along verges than in the adjacent interior habitats for both road types,indicating that roads are contributing as corridors for the dispersal of IAPS in the middle mountain areas of central ***,elevation,tree canopy,and disturbances(grazing/mowing/trampling)were found to be the key factors that determine spatial distribution of IAPS along road *** emphasize that regular monitoring of vegetation along the road verges can help with the early detection and control of potential IAPS in the region before they become problematic.

关键词： Biological invasions Dispersal corridor Invasive alien plants Transport infrastructure Himalayan mountains

Aging Coefficient, Creep Coefficient and Extrapolating Aging Coefficient from Short Term Test for Sealed Concrete

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Journal of Wuhan University of Technology(materials Science) 2011年第1期26卷 154-159页

作者： shrestha k m College of Civil Engineering Fuzhou University

Aging coefficient and creep coefficient are important parameters for creep analysis of any structure. With the aim to obtain those parameters, an experimental investigation is carried out on sealed concrete. Altogether ten specimens were tested, out of which four were for creep, two for shrinkage and remaining four for relaxation test. A year of relaxation test and two years of creep test results were analyzed to compute aging coefficient and creep coefficient. From regression analysis of observed and calculated aging coefficient using formula of Bazant and kim, modification for aging coefficient is performed and extrapolation equations are generated. Instead of ACI model, B3 model has been used to obtain compliance function as the parameters of B3 model seems more relevant to creep mechanism of concrete compared to that of ACI model.

关键词： stress strength ratio creep test experimental study B3 model regression analysis

Quantifying Creep of Concrete Filled Steel Tubes

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Journal of Donghua University(English Edition) 2010年第6期27卷 796-805页

作者：陈宝春 shrestha k m College of Civil Engineering Fuzhou University

Using age adjusted effective modulus(AAEm)method,creep of concrete filled steel tube(CFST)member was formulated considering of creep coefficient and aging *** CFST specimens were tested including eight for creep and two for *** experimental result was compared with the computed result using AAEm in which the creep coefficient was taken from calibration of ACI model based on experimental result on sealed concrete,and aging coefficient was supplied from relaxation test on sealed concrete ***,the creep of CFST member was analyzed using author's own subroutine to input concrete properties through user programmable feature(UPF)in ANSYS *** was made on authors' own experimental database,some existing experimental results,and results from AAEm and numerical ***,the conditions of applicability of AAEm method are put forward,and numerical approach to compute creep of CFST specimen is delineated.

关键词： age adjusted effective modulus(AAEm) concrete filled steel tube(CFST) creep test user programmable feature(UPF) subroutine numerical analysis

Topography and human disturbances are major controlling factors in treeline pattern at Barun and manang area in the Nepal Himalaya

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Journal of mountain Science 2017年第1期14卷 119-127页

作者： Parveen k.CHHETRI krishna B.shrestha David m.CAIRNS Department of Geography Texas A&M University College Station TX 77840 USA UiB Global Jekteviksbakken 31 PO Box 7800 5020 Bergen Norway

The alpine treeline ecotone is an important component of mountain ecosystems of the Nepal Himalaya; it plays a vital role in the livelihood of indigenous people,and provides ecosystem services. However,the region faces a problem of paucity of data on treeline characteristics at the regional and landscape scales. Therefore,we used Remote Sensing(RS),and Geographic Information Science(GIS) approaches to investigate cross-scale interactions in the treeline ecotone. Additionally,European Space Agency land cover map,International Center for Integrated mountain Development(ICImOD) land cover map,ecological map of Nepal,and United States Geological Survey Shuttle Radar Topography mission-Digital Elevation model were used to analyze treeline pattern at the regional scale. Digital Globe high-resolution satellite imagery of Barun(eastern Nepal) and manang(central Nepal) were used to study treeline patterns at the landscape scale. Treeline elevation ranges from 3300-4300 m above sea level. Abies spectabilis,Betula utilis,and Pinus wallichiana are the main treeline-forming species in the Nepal Himalaya. There is an east to west treeline elevationgradient at the regional scale. No slope exposure is observed at the regional scale; however,at the landscape scale,slope exposure is present only in a disturbed area(manang). Topography and human disturbance are the main treeline controlling factor in Barun and manang respectively.

关键词： Alpine Treeline mountain ecosystem Himalaya Remote Sensing(RS) Geographic Information Science(GIS)

Factors associated with crash severities in built-up areas along rural highways of Nevada:A case study of 11 towns

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Journal of Traffic and Transportation Engineering(English Edition) 2017年第1期4卷 96-102页

作者： Pramen P.shrestha k.Joseph shrestha Department of Civil and Environmental Engineering and Construction University of Nevada Las VegasLas VegasNV 89154USA Department of Engineering Technology Surveyingand Digital MediaEast Tennessee State UniversityJohnson CityTN 37614USA

In 2014, 32,675 deaths were recorded in vehicle crashes within the United States. Out of these, 51% of the fatalities occurred in rural highways compared to 49% in urban highways. No specific crash data are available for the built-up areas along rural highways. Due to high fatalities in rural highways, it is important to identify the factors that cause the vehicle crashes. The main objective of this study is to determine the factors associated with se- verities of crashes that occurred in built-up areas along the rural highways of Nevada. Those factors could aid in making informed decisions while setting up speed zones in these built-up areas. Using descriptive statistics and binary logistic regression model, 337 crashes that occurred in 11 towns along the rural highways from 2002 to 2010 were analyzed. The results showed that more crashes occurred during favorable driving conditions, e.g., 87% crashes on dry roads and 70% crashes in clear weather. The binary logistic regression model showed that crashes occurred from midnight until 4 a.m. were 58.3% likely to be injury crashes rather than property damage only crashes, when other factors were kept at their mean values. Crashes on weekdays were three times more likely to be injury crashes than that occurred on weekends. When other factors were kept at their mean value, crashes involving motorcycles had an 80.2% probability of being injury crashes. Speeding was found to be 17 times more responsible for injury crashes than mechanical defects of the vehicle. As a result of this study, the Nevada Department of Transportation now can take various steps to improve public safety, including steps to reduce speeding and encourage the use of helmets for motorcycle riders.

关键词： Speed-zone guideline Crash severity Binary logistic regression model Rural highway Nevada department of transportation

How does the stand structure of treeline-forming species shape the treeline ecotone in different regions of the Nepal Himalayas?

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Journal of mountain Science 2020年第10期17卷 2354-2368页

作者： Parveen k.CHHETRI Raju BISTA krishna B.shrestha Department of Earth Science and Geography California State UniversityDominguez HillsCarsonCalifornia90747USA Department of Biological Sciences University of BergenPO Box 7803N-5020BergenNorway

Stand structure dynamics are considered as major happenings in any forest as a response to environmental ***,this important topic is underrepresented in the treeline studies in the Nepal *** aimed to investigate site-as well as species-specific changes in morphometric features(basal diameter,crown cover,density,and height)along the elevational gradient across treeline ecotones in response to recent environmental *** stand structure characteristics of Abies spectabilis,Pinus wallichiana,and Betula utilis across the treeline ecotone of three study sites in Eastern(Barun),Central(manang),and Western(Dhorpatan)Nepal were analyzed to elucidate structural ***,eight transects(20 m×(60–250 m))across the treeline ecotone were *** of all life forms,trees(>2 m),saplings(0.5–2 m),and seedlings(m),within each transect were enumerated and sampled for the morphometric features and ***-specific and species-specific stand structure dynamics were *** rate of basal area increment was higher in Barun,but the manang treeline,despite profound regeneration in recent years,had a low annual basal area ***,the altitudinal distribution of age and morphometry were not consistent among those ***,intra-specific competition was not *** site-specific stand structure dynamics explain why treelines do not respond uniformly to increasing *** invokes,in further studies,the incorporation of the tree’s morphometric adaptation traits,phenotypic plasticity,and interactions between species genotype and the environment.

关键词： Climate change morphometry Nepal Himalayas Stand structure Treeline Tree-rings

Cholesterol crystal embolism leading to perforation of the gallbladder

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Hepatobiliary & Pancreatic Diseases International 2007年第6期6卷 653-655页

作者： Janine Tappenden Simon k. Suvarna Roger Ackroyd Badri m. shrestha Northern General Hospital Herries Road Sheffield S5 7AU UK

BACkGROUND: Cholesterol crystal embolism (CCE) from atherosclerotic arterial disease leading to perforation of the gallbladder is rare. We describe our experience of managing a patient with perforation of gallbladder caused by CCE. mETHODS: A 64-year-old man was admitted to this hospital because of acute abdominal pain with clinical features suggestive of peritonitis. He was known to suffer from atherosclerotic peripheral arterial disease and had undergone aortobifemoral bypass 17 years ago. A CT scan showed a collection of peri-hepatic fluid. The gallbladder was normal in appearance but contained multiple calculi. At laparotomy, free bile was observed in the peritoneal cavity, leaking from a pin-hole size peroration of the fundus of the gallbladder. Hence cholecystectomy was performed. RESULTS: The patient made an uneventful recovery. Histological study of the gallbladder showed chronic cholecystitis and obliteration of the lumen of the mural arteries with cholesterol crystals within, indicating CCE. CONCLUSIONS: Although perforation of the gallbladder following CCE of its mural arteries is rare, the diagnosis should be considered in patients with abdominal pain and known atherosclerotic arterial disease. management should include an early recognition of this condition, prompt institution of treatment, prevention of further insults by discontinuing or avoiding predisposing factors, and modification of cardiovascular risk factors.

关键词： cholesterol crystal embolism perforation gallbladder peritonitis