Bank Material Research Articles

Plant root and rhizome strength: Are there differences between and within species and rivers?

AbstractThe strength and architecture of roots and other below‐ground organs of riparian and aquatic plants affect plant resistance to uprooting and contribute to reinforcing river bank, bar and bed materials. Therefore, root properties are an important element in models for estimating river bank stability and such models may focus on the role of plants by using root strength–diameter relationships for the particular plant species that are present.Here we explore the degree to which there appear to be significant differences in strength–diameter relationships between and within species‐specific data sets obtained for two riparian tree/shrub (Populus nigra, Salix alba) and two emergent aquatic macrophyte (Sparganium erectum, Phalaris arundinacea) species in different European river environments.While the analysed data sets were not specifically collected to answer these research questions, the results are sufficiently compelling to make the case for the collection of a more comprehensive data set and its rigorous analysis. This would allow recommendations to be made on the degree to which (i) species‐specific or more general relationships between root/rhizome strength and diameter are appropriate, (ii) such relationships are applicable within and between rivers in different geographical regions and subject to different local environmental conditions, and (iii) further (minimalist) field observations are needed to calibrate such relationships for investigations of new locales or species. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Sequential Fecal Microbiota Transplantation for the Treatment of Fulminant Clostridium difficile Infection in a Bone Marrow Transplant Patient with Critically Low Neutrophil Count

Emerging evidence suggests fecal microbiota transplant (FMT) is safe and effective in immunocompromised patients for the treatment of C. difficile infection (CDI), however, it is not recommended for patients with severe neutropenia. Ongoing clinical trials using FMT in bone marrow transplant (BMT) recipients postpone FMT until neutrophil count normalizes. A 56 year old man post BMT on chemotherapy (day 4) for relapsing myeloma presented with diarrhea, fever (T= 101.6 F), and hypotension. His labs revealed an absolute neutrophil count (ANC) of 1,000/mm3, creatinine 0.8 mg/dL, albumin 2.2 g/dL, and lactate 4.4 mmol/L. Abdominal CT showed pancolitis without megacolon. He was diagnosed with fulminant CDI (by stool PCR) and started on oral vancomycin and intravenous metronidazole. His fever defervesced but diarrhea continued. On hospital day 3, he developed severe abdominal pain with ileus. CT findings were consistent with toxic megacolon with transverse colon measuring 9 cm in diameter. ANC dropped to a nadir of 10/mm3. He was not deemed a surgical candidate. Following a detailed discussion of procedural risks, infectious complication and lack of experience with FMT in severe neutropenia, FMT via colonoscopy was pursued. Pseudomembranes were noted. Oral vancomycin was reinitiated post-FMT and sequential FMTs were performed every 2-3 days according to our previously published protocol. While there was clinical improvement after each FMT, he relapsed after 24-48 hours. A total of 9 FMTs, using frozen stool bank material from a universal donor, were administered (5 via colonoscopy and 4 via nasoduodenal tube) over 19 days at which time he was amenable to discharge on oral vancomycin for 14 days. After completion of the outpatient vancomycin course, his diarrhea and abdominal pain returned and stool C. difficile was positive by PCR. Repeat inpatient colonoscopic FMT was performed and pseudomembranes were again noted (ANC= 6.3/mm3). This time, fidaxomicin was started and FMT was performed 3 days later. He did not experience recurrence of CDI during the 6 months of follow-up. Importantly, no procedure related or infectious complications were noted. This case highlights the safety of FMT(s) in a patient with critically low ANC. Further experience is needed in this case scenario, however, FMT appears to be a viable option for the treatment of fulminant CDI in a severely neutropenic patient.

Plant Community Influences on Intermittent Stream Stability in the Great Plains

The composition of the greenline plant community is linked to the stability of riparian ecosystems. Cool season exotic grasses are invading native plant communities across the northern Great Plains, potentially compromising streambank stability and increasing the risk of erosion within riparian ecosystems. To determine how the species composition of the greenline community impacts stream type and the risk of streambank erosion, thirty five reaches across five watersheds were sampled to determine the dominant greenline vegetation. At each reach, a cross-section was sampled to determine stream type, greenline vegetation, and risk of streambank erosion. Channel types were delineated using Rosgen’s classification of natural rivers. Canopy cover and composition was assessed using the line point intercept method along a 30.5 m transect in the greenline community. Plants recorded were grouped by their wetland indicator status for the central Great Plains. The Bank Erosion Hazard Index (BEHI) was used to assess the streams risk of erosion by calculating the difference between the bank height and bank full height, average plant rooting depth and density, bank angle degree, and the dominant texture of the bank material. Bank height ratio (BHR) was assessed as a measure of streambank stability and floodplain connectivity. A Nonmetric Multidimensional Scaling ordination was performed to analyze plant community influences. Analysis of the data determined that the most stable stream types (E and C channels), lower BEHI scores, and stable bank height ratios were associated with high amounts of litter and facultative wet species. In comparison, unstable F channels were associated with early successional species and bare ground. Sites with the higher BEHI scores were associated with greenlines comprised of upland and facultative upland and saline tolerant species. Late successional facultative wetland species were found to provide the most protection to intermittent streambanks.

Characteristics of intermittent turbulent structures for river bank undercut depth increment

The complex interplay between the resistive forces of the bank material and Reynolds shear stress of the turbulent flow field control the fluvial bank erosion. In-depth knowledge on the interactions of the flow-form at the river bank is a prerequisite to understand erosion mechanism and quantification of the erosion rate. Measurement at 1.5 m from the bank face as reported in the literature revealed that turbulent lateral flux of stream-wise momentum propagated towards the bank face that was held responsible for the removal of material from the bank face. Further experimental results from the literature depict that the stream-wise and lateral fluctuating velocity components deploy a random forcing effect on the river bank face which may be one of the primary agents for sediment particle entrainment from the bank face. It is gestated from these previous studies that the momentum flux and turbulent structures of the flow field has a great impact on the river bank erosion. Nevertheless, the previous field and experimental studies do not focus on the flow turbulence and sediment interaction that extracts information on the detailed temporal features of sediment entrainment process. Thus, the present study was carried out to understand the coupled dynamics of the effect of intermittent flow structures on the intermittent removal of river bank materials, and for advancing the knowledge on river bank erosion process. The present experimental study focuses on the evaluation of the turbulent flow characteristics when the undercut mechanism initiates in a cohesive river bank. Based on the results it is evident that moderate scale intermittent stream-wise flow structures probably imposes a periodic loading on the cohesive aggregates of the bank face. This accelerates the entrainment of aggregates from the bank face. The study also reveals that the undercut increment is a small scale intermittent process. Findings of the present study may be helpful for the improved design of bank protection measures.

Relationships between discharge parameters and cross-sectional channel dimensions of rivers in an active margin influenced by tropical climate: The case of modern fluvial systems in the Indonesian islands

The present study investigates (1) the relationships between discharge parameters and bankfull channel width (Wb) based on statistical analyses of hydrological data obtained from 649 sites at rivers on the Indonesian islands of Java, Sumatra, and Kalimantan, and (2) the relationship between depth parameters and Wb using channel cross sections obtained from 86 sites at rivers on these three large islands. These analyses are used to describe geomorphological and hydrological features of fluvial systems developed in a convergent margin under the influence of a low-latitude tropical climate. The relationship between mean discharge (Qmean) and Wb shows distinct variation within the Indonesian rivers, and reflects regional variations in annual rainfall of a tropical climate. The relationship between bankfull discharge (Qb) and Wb shows only minor variations across the three islands, regardless of bed and bank material types. The Qb–Wb relationship in the Indonesian rivers has a pattern similar to that of fluvial systems in Europe and the North American continent, which are influenced by mid- and high-latitude climates. Minor regional variation in the Qb–Wb relationship, regardless of the tectonic and climatic settings, suggests that the development of fluvial morphology is controlled mainly by flood-related episodic discharge. In contrast, the empirical equations between maximum channel depth (db) and Wb and between mean channel depth (dm) and Wb show distinct regional variations not only within the Indonesian fluvial systems but also in fluvial systems of Europe and the North American continent. These regional variations are thought to reflect the fact that db–Wb and dm–Wb relationships are controlled by the tectonic and climatic settings of a drainage basin, and factors such as the interrelationships between precipitation, vegetation, and slope. Consequently, selection of an appropriate dm–Wb (or db–Wb) equation combined with an appropriate Qb–Wb equation permits us to reconstruct spatial and temporal variations in hydrological features in both modern and ancient fluvial systems more precisely than applying previously proposed equations to fluvial systems formed in active margin and low-latitude climatic settings.

Fluvial Geomorphology, Root Distribution, and Tensile Strength of the Invasive Giant Reed, Arundo Donax and Its Role on Stream Bank Stability in the Santa Clara River, Southern California

Arundo donax (giant reed) is a large, perennial grass that invades semi-arid riparian systems where it competes with native vegetation and modifies channel geomorphology. For the Santa Clara River, CA, changes in channel width and intensity of braiding over several decades are linked in part to high flow events that remove A. donax. Nevertheless, the area of A. donax at the two study sites increased fivefold over a period of 28 years at one site and fourfold over 15 years at the second site. Effects of A. donax on bank stability are compared to those of a common native riparian tree—Salix laevigata (red willow)—at two sites on the banks and floodplain of the Santa Clara River. There is a significant difference of root density of A. donax compared to S. laevigata and the latter has a higher number of roots per unit area at nearly all depths of the soil profile. Tensile root strength for S. laevigata (for roots of 1–6 mm in diameter) is about five times stronger than for A. donax and adds twice the apparent cohesion to weakly cohesive bank materials than does A. donax (8.6 kPa compared to 3.3 kPa, respectively). Modeling of bank stability for banks of variable height suggests that S. laevigata, as compared to A. donax, increases the factor of safety (FS) by ~60% for banks 1 m high, ~55% for banks 2 m high and ~40% for banks 3 m high. For 3 m high banks, the FS for banks with A. donax is <1. This has geomorphic significance because, in the case of A. donax growing near the water line of alluvial banks, the upper 10–20 cm has a hard, resistant near-surface layer overlying more erodible banks just below the near-surface rhizomal layer. Such banks may be easily undercut during high flow events, resulting in overhanging blocks of soil and A. donax that slump and collapse into the active channel, facilitating lateral bank erosion. Therefore, there is a decrease in the lateral stability of channels if the mixed riparian forest is converted to dominance by A. donax.

An experimental investigation on effect of drawdown rate and drawdown ratios on stability of cohesionless river bank and evaluation of factor of safety by total strength reduction method

ABSTRACTThis paper presents an experimental investigation on the stability of a model river bank composed of homogeneous cohesionless soil under rapid drawdown condition. The effects of major influencing parameters controlling Factor of Safety (FoS) of a river bank under depletion of water level have been considered in the present study. A series of laboratory model studies have been carried out to investigate the cases of drawdown rate and drawdown ratios rendering the bank to maximum damage. Moreover, the effect of water level drawdown on the response variables namely pore water pressure, deformation of the bank profile, and shear strength of bank material have been observed and analysed. Stability analysis of the experimental model banks under drawdown conditions was carried out by evaluating FoS using the principle of reduced shear strength methodology. The in-situ total shear strength after each drawdown was measured using a laboratory vane shear apparatus. The minimum shear strength among these values has been identified. Now the FoS against each drawdown ratio has been computed from the ratio of total shear strength obtained after drawdown for that particular drawdown ratio to the minimum shear strength as obtained. This experimental programme examined the optimum combination of drawdown rate and drawdown ratio causing mass failure of the bank. It was revealed from the variation of pore pressure after drawdown that changes of pressures at points close to the toe of the bank slope is strongly controlled by the stress-state induced by drawdown. From the failure observations it was found that the drawdown rate is the dominating cause of maximum deformation of the bank than that of drawdown ratio. The findings of the present research work may help in predicting the actual failure scenario and stability condition of prototype river under similar boundary conditions.

Evidence of, and a proposed explanation for, bimodal transport states in alluvial rivers

Abstract. Gravel-bedded rivers organize their bank-full channel geometry and grain size such that shear stress is close to the threshold of motion. Sand-bedded rivers, on the other hand, typically maintain bank-full fluid stresses far in excess of threshold, a condition for which there is no satisfactory understanding. A fundamental question arises: are bed-load (gravel-bedded) and suspension (sand-bedded) rivers two distinct equilibrium states, or do alluvial rivers exhibit a continuum of transport regimes as some have recently suggested? We address this question in two ways: (1) reanalysis of global channel geometry datasets, with consideration of the dependence of critical shear stress upon site-specific characteristics (e.g., slope and grain size); and (2) examination of a longitudinal river profile as it transits from gravel to sand bedded. Data reveal that the transport state of alluvial riverbed sediments is bimodal, showing either near-threshold or suspension conditions, and that these regimes correspond to the respective bimodal peaks of gravel and sand that comprise natural riverbed sediments. Sand readily forms near-threshold channels in the laboratory and some field settings, however, indicating that another factor, such as bank cohesion, must be responsible for maintaining suspension channels. We hypothesize that alluvial rivers adjust their geometry to the threshold-limiting bed and bank material, which for gravel-bedded rivers is gravel but for sand-bedded rivers is mud (if present), and present tentative evidence for this idea.

Arnica montana subsp. atlantica: Really a subspecies?

In Arnica montana L. (Asteraceae) two subspecies are described, A. montana subsp. atlantica (AMA), present only on the Iberian Peninsula and A. montana subsp. montana (AMM) with a very wide distribution area. The morphological differences between the two subspecies are small and variable. Therefore, this concept is sometimes questioned. To establish the genetic background of the two subspecies, populations of AMA and AMM together with herbarium samples and DNA Bank material of AMM were tested with 12 microsatellite markers. A. montana propagates by seeds or by clonal propagation of its rhizome. In AMA, clonality was frequent while in AMM only one case of clonality could be identified. Therefore, further results were clone-corrected. Genetically, AMA separated very well from AMM with a GST between the subspecies of 0.81, genetically justifying the subspecies concept of A. montana. Genetic variability in AMA (Hexp = 0.28) was lower than in the AMM populations (Hexp = 0.70). A somewhat higher fixation index of AMA (FST = 0.17, compared to an FST = 0.08 for AMM) may indicate that geneflow in AMA is a bit more restricted than in alpine AMM. However, the fixation index of AMA is not deviating from Hardy–Weinberg equilibrium. No inbreeding was observed for AMA (FIS = 0.10) and AMM (FIS = 0.08).

The impact of using old germplasm on genetic merit and diversity-A cattle breed case study.

Artificial selection and high genetic gains in livestock breeds led to a loss of genetic diversity. Current genetic diversity conservation actions focus on long-term maintenance of breeds under selection. Gene banks play a role in such actions by storing genetic materials for future use and the recent development of genomic information is facilitating characterization of gene bank material for better use. Using the Meuse-Rhine-Issel Dutch cattle breed as a case study, we inferred the potential role of germplasm of old individuals for genetic diversity conservation of the current population. First, we described the evolution of genetic merit and diversity over time and then we applied the optimal contribution (OC) strategy to select individuals for maximizing genetic diversity, or maximizing genetic merit while constraining loss of genetic diversity. In the past decades, genetic merit increased while genetic diversity decreased. Genetic merit and diversity were both higher in an OC scenario restricting the rate of inbreeding when old individuals were considered for selection, compared to considering only animals from the current population. Thus, our study shows that gene bank material, in the form of old individuals, has the potential to support long-term maintenance and selection of breeds.

Development of Chute Cutoff in the Lower Course of River Mayo-Inne, Yola South, Nigeria


 
 
 
 The study investigates the development of chute cutoff in the lower course of River Mayo-Inne, Yola South LGA, Adamawa State, Nigeria. The study employed the integrated approach of Remote Sensing, Geographic Information System, Field Survey, Laboratory Analysis, Oral Interview and Personal Observation in examining the influences of some relevant channel planform parameters (Sinuosity Index, Cutoff Ratio and Braiding Index), land use/land cover, channel bank materials, water stage and channel depth on the development of the chute cutoff over a period of Twenty five years (1990-2015). Results revealed the drastic reduction of Sinuosity Index from 1.57 in 1990 to 1.46 in 2015, changing the channel from meandering to the straight pattern. The analysis of changes in cut-off ratio unveiled the development of chute cutoff in bend II, which ultimately separated the river flow, forming a weak braided channel with a braiding index of 0.43. These developments were attributed to incessant flooding in the study area and floodplain characteristics such as floodplain elevation, bank strength and changes in vegetal cover.
 
 
 

Stream channel erosion in a rapidly urbanizing region of the US-Mexico border: documenting the importance of channel hardpoints with Structure-from-Motion photogrammetry.

Urbanization can lead to accelerated stream channel erosion, especially in areas experiencing rapid population growth, unregulated urban development on erodible soils, and variable enforcement of environmental regulations. A combination of field surveys and Structure-from-Motion (SfM) photogrammetry techniques was used to document spatial patterns in stream channel geometry in a rapidly urbanizing watershed, Los Laureles Canyon (LLCW), in Tijuana, Mexico. Ground-based SfM photogrammetry was used to map channel dimensions with 1 to 2 cm vertical mean error for four stream reaches (100-300 m long) that were highly variable and difficult to survey with a differential GPS. Regional channel geometry curves for LLCW had statistically larger slopes and intercepts compared with regional curves developed for comparable, undisturbed reference channels. Cross-sectional areas of channels downstream of hardpoints, such as concrete reaches or culverts, were up to 64 times greater than reference channels, with enlargement persisting, in some cases, up to 230 m downstream. Percentage impervious cover was not a good predictor of channel enlargement. Proximity to upstream hardpoint, and lack of riparian and bank vegetation paired with highly erodible bed and bank materials may account for the instability of the highly enlarged and unstable cross-sections. Channel erosion due to urbanization accounts for approximately 25-40% of the total sediment budget for the watershed, and channel erosion downstream of hardpoints accounts for one-third of all channel erosion. Channels downstream of hardpoints should be stabilized to prevent increased inputs of sediment to the Tijuana Estuary and local hazards near the structures, especially in areas with urban settlements near the stream channel.

Genomic Prediction and Association Mapping of Curd-Related Traits in Gene Bank Accessions of Cauliflower.

Genetic resources are an important source of genetic variation for plant breeding. Genome-wide association studies (GWAS) and genomic prediction greatly facilitate the analysis and utilization of useful genetic diversity for improving complex phenotypic traits in crop plants. We explored the potential of GWAS and genomic prediction for improving curd-related traits in cauliflower (Brassica oleracea var. botrytis) by combining 174 randomly selected cauliflower gene bank accessions from two different gene banks. The collection was genotyped with genotyping-by-sequencing (GBS) and phenotyped for six curd-related traits at two locations and three growing seasons. A GWAS analysis based on 120,693 single-nucleotide polymorphisms identified a total of 24 significant associations for curd-related traits. The potential for genomic prediction was assessed with a genomic best linear unbiased prediction model and BayesB. Prediction abilities ranged from 0.10 to 0.66 for different traits and did not differ between prediction methods. Imputation of missing genotypes only slightly improved prediction ability. Our results demonstrate that GWAS and genomic prediction in combination with GBS and phenotyping of highly heritable traits can be used to identify useful quantitative trait loci and genotypes among genetically diverse gene bank material for subsequent utilization as genetic resources in cauliflower breeding.

ПЕРСПЕКТИВЫ ИСПОЛЬЗОВАНИЯ ФИНАНСОВЫХ ТЕХНОЛОГИЙ БАНКАМИ РАЗВИТИЯ НА ПРИМЕРЕ АЗИАТСКОГО БАНКА РАЗВИТИЯ И ВНЕШЭКОНОМБАНКА РОССИИ

The actual directions of development banks’ activity are determined. Financial technologies are actively used in the production and sale of financial services. Analysis of the materials of the Asian Development Bank, dedicated to the issues of using the digital economy, made it possible to identify the opportunities for the development banks of the fintech: identification and biometrics, rapid payments, large data analytics, blocking technology. Fintech will allow development banks to change the mechanism for planning and implementing projects, to increase the effectiveness of creating “chains” of value. Vnesheconombank’s projects related to fintech, in particular, the use of blocking technology in public procurement, are presented. At present, Vnesheconombank is successfully mastering Fintech and has good prospects for its use in practice.

Meandering Bend Development Process at Mawa Reach of the Padma River

The river Padma developed a meandering bend at the right bank of Mawa reach (reach 2) in meandering platform stage. The bend development process started in 1992 and continued in full form up to 2000. Maximum lateral extension occurred 780 m/yr in 1995-96 and average lateral extension was 450 m/yr. During the bend development process the Padma eroded more than 12,500 ha landmass at the bend location. The highly erodible bank materials and river characteristics allowed the bend formation at this location. A good number of samples measurement of different time indicated that the meandering wavelength of the river reach varied from 30 to 40 km. The meandering width of the river reach was about 17 km in 2000. The bend sustained only for 8 years (1992-2000) and was not so concave but the bend has great significance upon the river training work like the constricting Padma River Bridge. Satellite images of CEGIS and several definition diagram models of meandering bend have been developed to explain the bend formation process and bend characteristics.

Molecular Footprint of Kenya’s Gene Bank Repositories Based on the <i>cp</i>-Genome Signatures

While the mutational processes that subsume biological diversity can be revealed in great detail through phylogenetic inferencing using plastid markers, few studies document their use. Accurate phylogenic inference can provide a framework for addressing a host of important evolutionary questions including a context to reconstruct molecular evolution of an organism. Despite the obvious utility of plastid markers in illuminating biological enquiry, many important questions still abound. The use of cp-DNA gene sequence data for phylogenetic inference can have an enormous impact on plant phylogenetics and systematics. The repertoire of genetic diversity of Kenya’s Gene Bank repositories can be explored based on cp-genome signatures. This is because cp-DNA-based mutational changes are an important additional tool to the previous evidence available on plant evolution yet to be explored in biodiversity studies in Kenya. Taken together, these evolutionary changes can inspire development of realistic algorithms for phylogenetic inferencing based on molecular data. Phylogenetic reconstructions are at the very core of molecular evolution. Comparative sequence analyses of plastid markers can have utility beyond the study of phylogeny. The pattern of nucleotide substitution observed over evolutionary time can reflect functional constraints imposed due to natural selection. In line with this, it is possible to detect subtle anatomical variations associated with small fitness effects that can account for genetic diversity at varietal level. The lack of sequence information in Kenyan cowpea has limited the robust advancement of molecular markers use in dissecting diversity based on the putative plastid markers [1]. The present study sought to generate and upscale novel technologies such as genomics, DNA barcoding and bio-informatics in understanding molecular diversity of cowpea accessions from the Gene Bank of Kenya and ecotypes. A total of 298 sequences of cowpea germplasm conserved as in situ and ex situ in Kenya but sourced from phylogeographically diverse settings were examined and their genetic profiles were characterized and evaluated using molecular tools. The Gene Bank materials were purposefully sampled to develop subsets representative of the diversity in the genepool’s collection. We present an extensive study on characterizing the genetic diversity of cp-DNA gene sequence data for the cowpea accessions from the Nation Gene Bank of Kenya. The comparative sequence analyses and phylogenetic clustering of seven plastid markers widely used in the DNA barcoding of land plants provide insights on the molecular evolution of this vascular plant. The detailed and in-depth genome characterization herein greatly enriches the genetic profile of this important crop, which can help in reconstructing realistic models of mutational process during plant evolutionary history. This study addressed this gap by employing a DNA barcode library for cowpea to determine the loci that yield the best species resolution. As well, this study examined the efficacy of custom DNA barcode loci for identification success, and compared phylogenetic diversity measures between sites and among variants.

The contribution of botanic gardens to ex situ conservation through seed banking

Target 8 of the Global Strategy for Plant Conservation calls for ‘at least 75 per cent of threatened plant species in ex situ collections, preferably in the country of origin, and at least 20 per cent available for recovery and restoration programmes by 2020’.Botanic gardens make a significant contribution to ex situ conservation of wild species with more than a third of plant species represented in botanic gardens collections. These collections are a combination of living collection and seed banked material. Seed banking can provide an efficient form of conservation for wild plant genetic diversity.Information from Botanic Gardens Conservation International's (BGCI) databases (GardenSearch, PlantSearch, ThreatSearch and GlobalTreeSearch) has been analysed as well as survey data to report on global, regional and national seed banking trends.Information from BGCI's databases indicates that there are at least 350 seed banking botanic gardens in 74 countries. In total 56,987 taxa have been banked including more than 9000 taxa that are threatened with extinction. 6881 tree species are stored in ex situ seed bank collections. More than half (3562) of these tree species are single country endemics and represent species from more than 166 countries.This study suggests that institutions are increasingly conserving plant species via seed banking. However the majority of species in collections that have a conservation assessment are not threatened with extinction. This disjunction between species that are threatened and those conserved in seed banks needs to be addressed. Data from BGCI's databases can be used to enable prioritisation of threatened plant species for collection and conservation in seed banks. Further recommendations for botanic gardens involved in seed conservation are presented.

Effects of soil physico-chemical properties on stream bank erosion induced by seepage in northeastern Iran

ABSTRACTInternal erosion in composite stream banks can have negative effects on agricultural lands due to seepage, which can be affected by soil properties. We document the effects of physical and chemical properties of bank materials on the dimensions of cavities caused by internal erosion along the middle reach of the Atrak River. The goals were to (1) identify physico-chemical soil factors, (2) select significant factors affecting cavity dimensions, and (3) identify soil properties that could be used as indicators for future soil quality conservation programmes. Soil samples from nine locations with, on average, 25 cavities per 100 m, along a 50-km reach of the river were analysed. Using discriminant and factor analyses, five principal soil factors were identified, among which soil dispersion and Ca2+ content most influenced cavity dimensions. The sodium adsorption ratio and total dissolved salts for the non-cohesive layer were found to be the most important quality-related properties.

Bank Material Study for the Restoration of Historical Monuments in Michoacán, Mexico

Nowadays, most of the infrastructure building has inside its structural elements stony material. Over the years, the rocks have been widely used in construction, as stony material in a ceramic or cement matrix, or as a structural element in historical buildings. Physical characteristics are determined as: the present Humidity, Absorption, Density, specific Gravity, and mechanics as uni-axial Compression Resistance, besides Capillary Suction. We obtained images with Scanning Electron Microscopy (SEM) and we compared the physical and mechanical proofs with microphotographs. These studies help a restorer to use the rocks wisely and with the conviction that the rock is appropriate for the goals searched. The stony materials are found in a material bank called Comanja in Michoacán, Mexico.

Length scales and statistical characteristics of outer bank roughness for large elongate meander bends: The influence of bank material properties, floodplain vegetation and flow inundation

AbstractThis article explores the length scales and statistical characteristics of form roughness along the outer banks of two elongate bends on a large meandering river through investigation of topographic variability of the bank face. The analysis also examines how roughness varies over the vertical height of the banks and when the banks are exposed subaerially and inundated during flood stage. Detailed data on the topography of the outer banks were obtained subaerially using terrestrial LiDAR during low flow conditions and subaqueously using multibeam echo sounding (MBES) during near‐bankfull conditions. The contributions of various length scales of topographic irregularity to roughness for subaerial conditions were evaluated for different elevation contours on the bank faces using Hilbert–Huang Transform (HHT) spectral analysis. Statistical characteristics for discrete areas on the bank faces were determined by calculating the root‐mean‐square of normal distances from a triangulated irregular network (TIN) surface. Results of the HHT analysis show that the characteristics of roughness along bank faces composed primarily of non‐cohesive sediment, and eroding into cropland, vary with bank elevation and exhibit a dominant range of roughness length scales (~15–50 m). However, bank faces composed predominantly of cohesive material and carved into a forested floodplain have relatively uniform topographic roughness characteristics over the vertical extent of the bank face and do not exhibit a dominant roughness length scale or range of length scales. Additionally, comparison between local surface roughness for subaerial versus subaqueous conditions shows that roughness decreases considerably when the banks are submerged, most likely because of the removal of vegetation and eradication of small‐scale erosional features in non‐cohesive bank materials by flow along the bank face. Thus, roughness appears to be linked to the hydraulic conditions affecting the bank, at least relative to conditions that develop when banks are exposed subaerially. Copyright © 2017 John Wiley & Sons, Ltd.