Hill Slope Research Articles

Erosion and runoff reduction potential of vetiver grass for hill slopes: A physical model study

Severe erosion is caused by intense rainfall in tropical regions. The erodible soil of steep hill slopes, accompanied by destruction of vegetation due to human interventions results in accelerated erosion. A sustainable and cost-effective solution such as vetiver grass (Chrysopogon zizanioides) is, thus, required to control the erosion process. In the current study, 6 small-scale glass models: 1 bare and 5 with vetiver grass, having a slope angle of 37° have been constructed. One year after planting, artificial rainfall of extremely high intensity was applied to all 6 small models and the role of vetiver canopy and roots in erosion and runoff control was observed. To see the effect of soil texture, one among these 5 models was made with silty sand and others contained sandy silt. The results demonstrated that, for sandy silt, the inclusion of vetiver reduced the soil loss by 94%–97%, and soil detachment rates were lowered by 95%. The average runoff also was reduced by 21%. The canopy cover showed a positive impact on reducing both quantities. An increase in average root diameter from 1.6 to 2.5 mm increases the soil loss due to its negative impact on added cohesion. The added cohesion showed a linearly negative correlation with soil loss. A composite system of vetiver and jute geotextile was most effective in erosion reduction among 4 vegetated models with sandy silt. Under same vetiver planting layout, the grass covered model of silty sand yielded 84% lower erosion and 62.5% lower runoff than the grass covered one with sandy silt. Thus, vetiver was more effective in erosion and runoff reduction for soil with a greater percentage of sand, and soil type dominated the erosion process.

Effect of DEM resolution on assessing hydrological connectivity in tropical and semi-arid basins of central Mexico

• Relief and vegetation should be considered for DEM resolution selection. • High resolution is needed where heterogeneous and dispersed vegetation is present. • Distance to sinks may explain spatial differences in the index of connectivity. • Results show a balance between accuracy and processing for selecting DEM resolution. • Our findings can be considered for hydrological modelling. Assessment of hydrological connectivity is a valuable tool for water management. It enables various environmental factors related to water-mediated transport of matter and energy within or between elements of a system to be identified and incorporated into hydrological models. The index of connectivity (IC) is widely used to quantify hydrological connectivity; however, it may be influenced by the spatial resolution of the digital elevation model (DEM), which is one of the common inputs, as pixel size modifies some basin parameters. Several DEMs available on open-access platforms, with spatial resolutions from 5 to 30 m (LiDAR, ALOS, MEC, ASTER, SRTM), were compared to identify differences between IC in two basins with contrasting environments (Site 1: steep slope terrain with warm-humid climate, and Site 2: gentle hill slopes with semi-arid climate). Differences in perimeters were analyzed using GLM Repeated Measures ANOVA, while for differences in IC, one-way ANOVA was used. Relationships between IC subtracted maps and basin parameters were explored with classification and regression trees (CART). Basin perimeters and IC varied as a function of DEM resolution, but environmental factors such as relief and land use/cover seemed to influence IC maps. Distance to sinks was one of the variables explaining spatial differences in IC between DEMs. The selection of DEM spatial resolution for hydrological connectivity analysis should be based on the characteristics of the study area, economic and technological issues, and whether the objectives can be met with the available DEM resolution.

Soil Moisture Control of NO Turnover and N2O Release in Nitrogen-Saturated Subtropical Forest Soils

Acid forest soils in South China experience a chronically elevated input of atmospheric nitrogen (N), turning them into hot spots for gaseous N emissions. Soil moisture is known to be a major controller for the partitioning of gaseous N loss to nitric (NO) and nitrous oxide (N2O), which may be of particular relevance in the monsoonal climate of South China. To study this partitioning in more detail, we determined gas phase kinetics of NO and N2O release during laboratory dry-out of acidic surface soils from the headwater catchment TieShanPing (TSP), situated close to Chongqing, SW China. Soils were sampled from two hydrologically distinct environments, a well-drained hill slope (HS), and a periodically flooded groundwater discharge zone (GDZ). Production and consumption of NO were studied in an automated flow-through system purged with NO-free or NO-spiked air. Production rates peaked at 21% and 18% water filled pore space (WFPS) in HS and GDZ soils, respectively, suggesting nitrification as the dominant process of NO formation in both landscape units. In HS soils, maximum production and consumption occurred at the same WFPS, whereas GDZ soils displayed maximum NO consumption at higher WFPS than maximum production, suggesting that denitrification is an important NO sink in GDZ soils. Net N2O release was largest at 100% WFPS and declined steadily during drying. Integrated over the entire range of soil moisture, potential NO-N loss outweighed potential N2O-N loss, suggesting that N-saturated, acid forest soil is an important NO source.

Effect of mulch types on soil moisture, soil fertility, growth and yield of pineapple (Ananas comosus) in hill zone of Assam

A field experiment was carried out in Hill Zone of Assam from 2017 to 2019 with the objective of identifying mulch types on soil moisture retention, soil physical and chemical properties, growth and yield of pineapple (Ananas comosus) grown in hill slopes under farmers’ field condition. The treatments consisting of mulching with black polythene, dhaincha (Sesbania aquleata) as mulch, frequent slashing of weeds, soil mulching (soil mounding) and farmers practice without any mulch as control were evaluated in a randomized block design. Soil moisture content at 0-30cm depth was significantly different among the mulching methods and highest value of 14.2% at 0-30cm depth at harvesting was recorded in black polythene followed by slashing of weeds (13.1) and minimum in farmers practice. Soil texture was not affected by various mulches but there was a decline in bulk density with mulching and minimum value of 1.23 kg m-3 was recorded under slashing of weeds. Higher organic carbon (8.8 g kg-1), available nitrogen (341.8 kg ha-1), phosphorus (9.5 kg ha-1) and potassium (100.6 kg ha-1) were recorded in organic mulches i.e. slashing of weeds and dhaincha. The highest yield attributing characters and fruit yield of 38.3t ha-1 was recorded in the black polythene treatment followed by dhaincha as mulch (36.5 t ha-1) and frequent slashing of weed (35.6 t ha-1). Soil mulching and farmers practice recorded significantly lower yield than other treatments.

Effect of mulch types on soil moisture, soil fertility, growth and yield of pineapple (Ananas comosus) in hill zone of Assam

A field experiment was carried out in Hill Zone of Assam from 2017 to 2019 with the objective of identifying mulch types on soil moisture retention, soil physical and chemical properties, growth and yield of pineapple (Ananas comosus) grown in hill slopes under farmers’ field condition. The treatments consisting of mulching with black polythene, dhaincha (Sesbania aquleata) as mulch, frequent slashing of weeds, soil mulching (soil mounding) and farmers practice without any mulch as control were evaluated in a randomized block design. Soil moisture content at 0-30cm depth was significantly different among the mulching methods and highest value of 14.2% at 0-30cm depth at harvesting was recorded in black polythene followed by slashing of weeds (13.1) and minimum in farmers practice. Soil texture was not affected by various mulches but there was a decline in bulk density with mulching and minimum value of 1.23 kg m-3 was recorded under slashing of weeds. Higher organic carbon (8.8 g kg-1 ), available nitrogen (341.8 kg ha-1 ), phosphorus (9.5 kg ha-1 ) and potassium (100.6 kg ha-1 ) were recorded in organic mulches i.e. slashing of weeds and dhaincha. The highest yield attributing characters and fruit yield of 38.3t ha-1 was recorded in the black polythene treatment followed by dhaincha as mulch (36.5 t ha-1 ) and frequent slashing of weed (35.6 t ha-1 ). Soil mulching and farmers practice recorded significantly lower yield than other treatments.

Characteristics of Engineering Geology in Talegong Road, Talegong, Garut, West Java, Indonesia

Talegong road, Garut, West Java, is provincial road with a length of 7 kilometers that connects Garut and Bandung. The road segment KM 2.3 – KM 7 is located between the steep slope of high hills and has potential for landslide. To find out the landslide potential, determining the characteristics of geology and engineering geology at this road segment are needed. The methods used in this research are engineering geology mapping (geomorphology, lithology, structural geology and rock mass quality) and laboratory analyses of soil and rock properties index, shear strength test, petrographic analysis and uniaxial compressive strength test. The results of geological mapping show the aspect geomorphological in the area consists of high hills with rather steep to very steep slopes. Lithological, the area consists of aphanitic andesite and porphyritic andesite. The area is dominated by Northeast – Southeast stress regime. In term of rock mass quality, the study area consists of three class with value in Rock Mass Rating classification, which are good rock, fair rock, poor rock and no value rock (soil). The study area is divided into three units in the engineering geological map: (1) unit A has fair – good rock (II – III) with rather steep - very steep slope with low landslide potential, (2) unit B has fair rock (III) with steep – very steep slope with medium landslide potential, and (3) unit C has poor – no value rock or soil (IV – 0) with a very steep slope with high landslide potential.

Integrated approach for landslide hazard assessment in the High City of Antananarivo, Madagascar (UNESCO tentative site)

The High City of Antananarivo is one of the most important cultural heritage sites of Madagascar, on the UNESCO Tentative List since 2016. Built on the hilltop of the Analamanga Hill, a granite ridge overlooking the Ikopa River valley, it is renowned for its baroque-style palaces, such as the Rova royal complex, and neo-Gothic cathedrals dating back to the nineteenth century. During the winter of 2015, the twin cyclones Bansi and Chedza hit the urban area of Antananarivo, triggering floods and shallow landslides, as well as causing thousands of evacuees and many casualties. Between 2018 and 2019 several rockfalls occurred from the rock cliffs of the Analamanga hills, destroying housings and killing over 30 people. Both events showed that landslides can pose a high risk to the safety of the inhabitants, the infrastructure, and the cultural heritage of the High City. To assess the landslide hazard in the Analamanga Hill area, an integrated approach was adopted by means of the following actions: (i) creation of a multitemporal detailed scale landslide map; (ii) geotechnical characterization of the involved materials; (iii) analysis of landslide susceptibility in soils/loose deposits; (iv) runout analysis of debris flows channeling within large creek gullies; (v) landslide kinematic analysis of the rockmass; (vi) simulation of rockfall trajectories; (vii) analysis of rainfall data. The results show that the main factors affecting landslides are slope, lithology, creek-gully erosion, and anthropization, while most of the landslide events are clearly triggered by heavy rainfall. The landslide-prone areas (the phenomena include shallow landslides, rock falls, and debris flows) are located primarily along the cliff bounding the western hill slope, the southeastern sector (where abandoned quarries form large slope cuts), and subordinately in the steep creek catchment just east of the Rova. The thematic maps produced represent fundamental land use management tools to be used in Geo Disaster Risk Reduction (GDRR) by scientists, practitioners and the decision-makers involved in the High City protection and conservation. The study conducted represents an important contribution for improving the knowledge on landslide processes in an area with limited data such as Madagascar, and may be reproduced in cultural heritage sites characterized by similar geomorphological and urban scenarios.

Role of vegetation in improving the stability of a tropical hill slope in Guam

This paper aims at investigating and highlighting the hydrological benefit of vegetation by way of root water uptake (RWU) in preventing or at least delaying rainfall-induced slope failures in the island of Guam. In particular, the results of field instrumentation and monitoring by way of moisture and suction sensors, laboratory and field testing of geotechnical and hydrological soil properties and rainfall-induced numerical simulations of transient seepage coupled with slope stability analysis are presented. Two case studies, one with a 45° slope and another with a 60° slope, were studied for three different case scenarios. Only one set of vegetation and root reinforcement data was idealised, and the results confirm that matric suction was induced within shallow depths due to RWU helping in providing a buffer, which prevents slope failure during lower-precipitation events. However, this stabilisation effect ceases after saturation during long-duration precipitation. On the other hand, complementary analysis considering the mechanical root reinforcement effect showed that it is a dominating factor in improving the factor of safety even after the slope becomes saturated. In general, native hill slopes with a 45° angle were stable, but the one with a 60° angle failed when a real case rainfall event with climate–vegetation data was applied in this study.

Polychaeta fauna in the northeastern Barents Sea

The northeast of the Barents Sea (the area between the Franz Josef Land and Novaya Zemlya archipelagos) is one of the little-studied areas characterized by a complex structure of the hydrological regime, bottom relief and bottom sediment structure. This area is characterized by the predominance of brown soils with a large number of foraminifera shells, which affects the species composition and structure of benthic communities. The species composition and quantitative characteristics of polychaetes in the northeastern part of the Barents Sea were analyzed on the basis of material collected in December 2019 during Murmansk Marine Biological Iinstitution expeditions on the r/v Dalnie Zelentsy . Faunal complexes of polychaetes have been identified in the study area depending on environmental conditions (type of bottom sediments, depth, hydrological conditions). In the areas of marginal troughs, the detritophagus Spiochaetopterus typicus dominates in terms of biomass and abundance, forming abundant settlements on soft silty-sandy, silty-clay soils. Low values of biomass and abundance have been noted on brown silts with a large number of foraminifera, dominated by Laonice cirrata . On the slopes of underwater hills, washed more strongly by bottom currents, on rough sandy soils with low nutrient content, the dominance of Nephtys ciliata has been noted. The species Sphaerodoridium kolchaki sp. n. recently encountered in the Barents Sea has been noted in the study area as well. The obtained data complement information on the species composition of the northeastern part of the Barents Sea and make it possible to trace further changes in the composition and structure of benthic communities.

Impact of slope position on soil erodibility indicators in rolling hill regions of northeast China

The position of the rolling hill slope has considerable effects on soil properties and crop growth via the spatial heterogeneity of erosion intensity, which in turn probably impacts soil erodibility. However, few studies have been carried out to quantify the potential effects of slope position on soil erodibility indicators on long gentle slope. This study aimed to quantify the spatial variations in soil erodibility indicators of soil cohesion (Coh), saturated hydraulic conductivity (Ks), mean weigh diameter (MWD), mean number of drop impact (MND), soil penetration resistance (PR), soil structural stability index (SSI), soil erodibility of K factor, slaking rate (SR), organic matter content (SOC) and a comprehensive soil erodibility index (CSEI) on two typical rolling hill slopes in northeast China. Soil properties, root mass density (RMD) and litter mass density (LMD) were determined to explain the spatial change of soil erodibility indicators with slope position. The results showed that Coh, MWD, MND, PR and SOC declined from upper to middle, and then increased continuously until to lower position. The distinctly opposite changes were found in Ks and SR with slope position. No distinct variation was observed in K factor and SSI with slope position. For both two slopes, CSEI increased from upper to middle, and then decreased quickly to lower position. Compared to middle position, the mean reduces of two tested hillslopes were 51.72%, 14.74%, 24.28% and 72.52% for upper to lower positions, respectively. The results of Path analysis showed that SOM was the main factors contributing to the variation of CSEI with slope position. This study confirmed that the middle position is the most susceptible area to erosion on long gentle rolling hillslope. The results are helpful to understand the spatial variation in soil erosion intensity and design soil conservation measures on long gentle slopes.

Introduction On the Histories and Futures of Black New England Studies

Introduction On the Histories and Futures of Black New England Studies

Probabilistic Seismic Hazard Analysis (PSHA) to estimate the input ground motions for Co-seismic landslide hazard assessment: A case study on Himalayan highways, Sikkim India

Sikkim, the North-Eastern state of India, along with its neighbouring region is recognized as a part of the ‘Alpine-Himalayan global seismic belt’, which is one of the most seismically active areas of the world. Four significant earthquakes with a magnitude higher than Mw = 8.0 were reported in this area in earlier years of 1897, 1905, 1934, and 1950. The 2011 (Mw = 6.9) Sikkim and 2015 (Mw = 7.8) Gorkha Nepal earthquakes call attention to the need for a more accurate understanding of seismic characteristics in the Sikkim and their nearby region to minimize loss of life and properties due to future earthquakes and related co-seismic hazards. This study aims to estimate the Peak Ground Acceleration (PGA) having a known Probability of Exceedance (PoE) along Gangtok to Lachung and Gangtok to Tsomgo Lake; two strategic highways within Sikkim. The PGA with a known PoE is an essential input required for earthquake-triggered landslide susceptibility analysis on a regional scale as well as for the dynamic slope stability assessment of the prevailing hill slopes along the highways corridor in Sikkim. Therefore, a Probabilistic Seismic Hazard Analysis (PSHA) of the highway corridors in Sikkim is presented utilizing the updated earthquake catalogue, modified seismic sources, and next-generation attenuation relationships. The Uniform Hazard Spectra (UHS) and total hazard curves corresponding to the bedrock site conditions are generated employing ‘EZ-FRISK’ software. The variations of PGA having a 10% PoE in 50-years along the highways are estimated to identify the critical sections based on the ground acceleration parameter.

A STUDY OF THE ROAD-SIDE VENDORS ON NH8 THROUGH THE 'HATHAI KOTOR' RANGE IN TRIPURA

A street vendor is a person who offers goods or services for sale to the public without having a permanently built structure but with a temporary static structure or mobile stall (or head-load). Street vendors could be stationary and occupy space on the pavements or other public/private areas, or could be mobile, and move from place to place carrying their wares on push carts or in cycles or baskets on their heads, or could sell their wares in moving buses. In this study, the vendors are small vendors sitting in the road-side of National Highway (NH8) through the Hathai Kotor (the then Baromura) hill range between Champaknagar and Teliamura of Tripura, India, who sell mainly agricultural produces grown in their kitchen garden or collected from the hill slopes and jungles. The socio-economic condition of these vendors; the challenges they are facing and their economic condition during covid19 pandemic is studied in this paper. They are facing challenges from various fronts including number of buyers, locational and geographical disadvantages. Covid19 restrictions have worsened their economic condition and posed threat on their subsistence. KEY WORDS: road-side vendors, agricultural goods, subsistence

A Study on Seismic Response of RCC Buildings on Hill Slopes Using STAAD.Pro

Abstract: The majority of India's hilly regions are prone to earthquakes. A building on a steep slope is distinct from other structures. That is to say, structures that are to be constructed on hilly terrain have a higher risk factor of falling prey to seismic activities as compared to their counterparts built on a rather plainer terrain. The numerous floors/storeys of such a structure step back towards the hill slope, and buildings may also have setbacks. As such, the column of a hill structure sits at different heights on the angle of the terrain; its analysis differs from that of buildings on level ground. The current study looked at G+3 and G+4 structures with different slope angles, such as 00 , 7.50 , 150 , 22.50 , and 300 . Both Step back and Step back & set back types of building configurations have been studied in this paper. The earthquake forces are calculated according to IS: 18932002; the structures are situated in seismic zone IV, with a damping ratio of 5%. Linear Static and Linear Dynamic methods were employed to conduct the seismic study. To investigate the influence of shifting column heights in the ground level due to sloping ground, a 3-dimensional analytical model of building plan was created and the same was studied using the structural analysis application "STAAD.Pro." To quantify the effects of diverse sloping terrain, response parameters like top storey displacement, base shear, shear in bottom storey column, and time period were thoroughly studied. It has been discovered that short columns on the elevated side of the terrain/slope experience a greater shear force as compared to columns of increased height on the lower side of the terrain. Under earthquake stresses, Step back & Setback structures showed better resilience to seismic forces as compared to Step back buildings. Step back setback buildings have substantially lower base shear and top floor displacement than setback buildings on sloping land. Keywords: Earthquake, Slope, STAAD.Pro, Step back, Step back & set back

A Diagnostic Survey on Methods Used to Predict Land Used for Shifting Cultivation Using Satellite Images

Abstract: Shifting cultivation and its practice are said to be pernicious and eco-hostile from the standpoint of dependence of tribal people on forest-clad hill slopes. In this farming, the soil bone diseases are also reduced significantly. This is an example of subsistence, extensive, and arable farming. In the rainforest, it is one of the traditional forms of agriculture. The Amazonian Indians mostly do this farming in South America. They use the land for 2 to 3 years before moving to another area. There is a huge part of land which is used for Shifting cultivation for several years. Because of its spread, growing loss of potential green cover and related imbalance in eco-habitat, the Forest Policy, 1952 and the National Commission on Agriculture, 1976 suggested that shifting cultivation be banned, providing the tribal practitioner alternative systems of livelihood support. In this paper we are going to look at different methods and algorithms used to build AI models to predict Land used for Shifting Cultivation. Keywords: Shifting Cultivation, Remote Sensing, LULC, Image Processing, Neural Networks.

Evaluation of climate change impact on soil erosion in the integrated farming system based hilly micro-watersheds using Revised Universal Soil Loss Equation

Increased rainfall intensity under changing climate scenarios threatens the sustainability of cropland due to soil erosion in the Himalayan mountain ecosystem. This study aimed to identify the resilient integrated farming system (IFS) based land use practices in hilly micro-watersheds (HMWs) under projected climate change scenarios. The IFS based land uses considered were livestock with fodder crops (HMW1), forestry (HMW2), agroforestry (HMW3), food and fodder crops (HMW4), agri-horti-silvi-pasture (HMW5), horticulture (HMW6), and abandoned shifting cultivation (HMW7, as traditional jhum), established on the hill slope (>32.0 to 53.0%) in Meghalaya, India. The Revised Universal Soil Loss Equation (RUSLE) was calibrated and validated satisfactorily (RMSEa: 0.3 to 1.2 t ha−1 yr−1; NSE: 0.6 to 0.9) using 24 years measured soil loss data for each HMWs. The model was most sensitive to soil erodibility (S = 0.9 to 1.1) followed by plant cover (S = 0.6 to 1.0) in simulating the soil loss in the hilly micro-watersheds. Simulated soil losses in different HMWs ranged from 11.5 to 32.7 t ha−1 yr−1 under the baseline climate (1976 to 2005). The soil loss is projected to increase in the range of 7.3 to 15.3% under different RCPs (RCP2.6 to RCP8.5). The HMW with shifting cultivated IFS were the most vulnerable to climate change, as soil loss increased by 1.7 to 8.4 t ha−1 yr−1 over baseline (32.7 t ha−1 yr−1). However, HMW with horticulture based IFS followed by agroforestry showed the most resilience to climate change and manifested a minimal increase (0.6 to 3.1 t ha−1 yr−1) over baseline soil loss (11.5 to 12.0 t ha1 yr−1). Adoption of horticultural and agroforestry based IFS on the hill slope of Eastern Himalayan ecosystem is an effective measure to control soil erosion.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ПРОЦЕССА ДИНАМИЧЕСКОГО ВЗАИМОДЕЙСТВИЯ ЛЕСНЫХ МАШИН И ТРЕЛЕВОЧНЫХ СИСТЕМ С ПОЧВОГРУНТОМ ПРИ РАБОТЕ НА СКЛОНАХ

In the Russian Federation, a significant part of the forest fund is located on the permafrost. Permafrost forests play a global ecological role by depositing large amounts of carbon. However, when a forest reaches the age of obsolescence, this carbon is released into the atmosphere as it decays. Therefore, from an ecological point of view, permafrost forests should be cut down when they reach the age of maturity, in compliance with the requirements for their restoration. Many of these regions have large reserves of mature and overmature commercial forests, and a significant portion of these reserves are located in places difficult to access, not only in relation to the development of road networks, but also on the terrain. At present the overwhelming majority of timber felling in Russia is performed with the help of modern machinery complexes, which mainly include wheeled forestry machines of different layout and purpose (harvesters, forwarders, skidders, etc.). With the help of special technical solutions, such as winches integrated into the transmission, or self-propelled winches (T-winch, ROB), these machines can be successfully operated on fairly steep slopes. The problem of negative effect of wheeled forest machines and skidding systems based on them not only remains actual, but becomes even more urgent, as the ecosystems of mountain forests, forests on slopes of hills, etc. are the most vulnerable and exposed to water and wind erosion. The developed mathematical model, which allows evaluating the dynamic impact of a wheeled forestry machine (skidder system) on the ground while working on slopes with taking into account the main technical and technological factors, is presented in the article

Characterized source model of the 2013 Lushan earthquake (Mw 6.6) by the empirical Green\u2019s function method

Ground motions near the source area of the mainshock of the 2013 Lushan earthquake (Mw 6.6) in Sichuan Province in China were reproduced using the characterized source model and the empirical Green’s function method (EGFM). The best-fit characterized source model consisted of one strong motion generation area (SMGA) and a background area. The synthesized ground motions of the characterized source model were in fairly good agreement with the observed ground motions in the frequency range from 0.5 to 30.0 Hz at ten strong motion stations. For the 2013 Lushan earthquake (Mw 6.6), both the relationships between the SMGA and the seismic moment, and those between the flat amplitude of the acceleration source spectrum in the short period and the seismic moment almost followed the empirical scaling relationships of inner fault parameters developed for crustal earthquakes. The reasons for the largest peak ground acceleration (PGA) (> 1 g) in the strong-motion observation history of China recorded at the 51BXD strong motion station were investigated from the source and site effects. We found that the directivity effect did not contribute to the largest record by comparing the effect of different positions of the rupture starting point on the synthesized ground motions. The nonlinear effect of shallow layers was negligible, as indicated by the similarity of the earthquake H/V spectral ratios between the mainshock and EGF events. A large shear-wave velocity contrast might not exist in the shallow layers as the station was situated on the slope of a small rock hill. Finally, we agreed with previous studies that the hanging-wall effect and topographic effect might be the reasons for generating the largest record at Station 51BXD.Graphical

POD analysis of spatiotemporal characteristics of wake turbulence over hilly terrain and their relationship to hill slope, hill shape and inflow turbulence

In this study, the turbulent wake flow fields over isolated 2-D ridges and 3-D hills with different slopes and oncoming flow conditions are predicted by large-eddy simulations (LES). The coupling effects of hill slopes, hill shapes and inflow turbulence on the spatiotemporal characteristics of wake turbulence over hilly terrain are clarified in terms of turbulent statistics and unsteady flow patterns. The snapshot-based proper orthogonal decomposition (POD) technique is then adopted to elucidate the physical meaning of wake turbulence over hilly terrain. The numerical results show that the vertical distributions of turbulent statistics and the unsteady flow patterns in the wake of hilly terrain are jointly determined by hill slopes, hill shapes and oncoming flow conditions. Additionally, the snapshot-based POD method is capable of reconstructing a large amount of fluctuating kinetic energy in the wake of hilly terrain with a few low-order POD modes. Moreover, the primary wake patterns and their relations to hill slopes, hill shapes and oncoming flow conditions are identified. On the horizontal plane, the wake turbulence structures of 3-D gentle/steep hill are dominated by the asymmetric elongated streak structures and a pair of counter-rotating vortices, respectively. On the vertical plane, the main patterns of hill wake are often featured by the recirculating flow, and the size of recirculation bubble is highly dependent on hill slopes and hill shapes.

A translational rat model to assess glomerular function changes with vancomycin

Vancomycin (VAN) causes acute kidney injury as defined by serum creatinine (SCr) increase. Glomerular filtration rate (GFR) is the gold standard for defining kidney function, and SCr is often used as a GFR surrogate; however, SCr changes can lag behind acute functional decline. We sought to define the rate and extent of GFR change for VAN in a translational rat model. Male Sprague Dawley rats received VAN 150 mg/kg/day intravenously (n=6) or saline (n=5) once daily followed by an intravenous injection of fluorescein isothiocyanate-sinistrin (FITC-sinistrin) for 3 days. FITC-sinistrin fluorescence was monitored transdermally prior to VAN administration and daily during treatment. GFR was calculated from FITC-sinistrin clearance. A mixed-effects model compared urinary biomarkers and GFRs between treatments and across days of dosing. Urinary biomarkers for injury and GFR were compared between treatment groups and correlated with VAN kidney accumulation. Mean GFR for saline-treated animals was 1.07, 1.20, 1.15 and 1.24 mL/min/100g body weight (b.w.) pre-treatment and at Days 1-3, respectively. VAN-treated rats had lower GFR after treatment (0.457, 0.584 and 0.759 mL/min/100g b.w. on Days 1-3, respectively; P ≤ 0.05). KIM-1 and clusterin were elevated on Day 1 for VAN-treated animals. The relationship between VAN accumulation in the kidney with GFR and biomarkers followed a four-parameter Hill slope (R2=0.6 and R2=0.9, respectively). Rats receiving VAN had a significant decline in GFR immediately following the first dose, which correlated with increasing VAN concentrations in the kidney and urinary biomarkers.