Applicability of Diffusive model for mud-flows: An unsteady analysis

applied to the analysis of debris- and mud- flow dynamics. For this reason, the study of their applicability conditions represents an important concern. The present work investigates on the applicability conditions of the Diffusive Wave Model (DWM) for the prediction of mud-flows of shear-thinning fluid represented by a power-law rheology. The study has been carried out through the numerical solution of the DWM and the Full Wave Model (FWM) in unsteady conditions with hydrographs of different durations assigned at the channel inlet. The analysis has considered different rheological indexes, several values of the Froude (F) and of the Kinematic Wave (K) numbers. Predictions of DWM and FDM have been compared considering the mean value of dimensionless errors on maximum flow depth,ε∗h, and maximum discharge ε∗q. Positive (negative) error leads to an overestimation (underestimation) of the maximum flow depth and flow discharge in the prediction of the DWM. In the present analysis the DWM is considered safely applicable in case of underestimation, i.e. for positive values of ε∗h and ε∗q. Negative errors are acceptable if their absolute value is smaller than 5%. For all the investigated values of the governing parameters, the performance of the DWM has been found to strongly depend on the value of the rheological index, worsening as the fluid rheology becomes more shear-thinning. Regardless of the hydrograph duration, and for fixed power-law exponent (n) and F values, results indicate the existence of limiting values of the kinematic wave numberKh and Kq above which the DWM is applicable in terms of maximum depth and discharge, respectively. For K values smaller than Kh and Kq, the DWM applicability depends also on the hydrograph duration. In these conditions and for several values of the (F, n) pair, the threshold values of the hydrograph duration necessary for DWM applicability have been identified. The presented applicability criteria represent a useful guideline for the practical application of the DWM in assessing the hazard of a mud flood

Impact Force of a Geomorphic Dam-Break Wave against an Obstacle: Effects of Sediment Inertia

The evaluation of the impact force on structures due to a flood wave is of utmost importance for estimating physical damage and designing adequate countermeasures. The present study investigates, using 2D shallow-water approximation, the morphodynamics and forces caused by a dam-break wave against a rigid obstacle in the presence of an erodible bed. A widely used coupled equilibrium model, based on the two-dimensional Saint–Venant hydrodynamic equations combined with the sediment continuity Exner equation (SVEM), is compared with a more complex two-phase model (TPM). Considering an experimental set-up presented in the literature with a single rigid obstacle in a channel, two series of tests were performed, assuming sand or light sediments on the bottom. The former test is representative of a typical laboratory experiment, and the latter may be scaled up to a field case. For each test, two different particle diameters were considered. Independently from the particle size, it was found that in the sand tests, SVEM performs similarly to TPM. In the case of light sediment, larger differences are observed, and the SVEM predicts a higher force of about 26% for both considered diameters. The analysis of the flow fields and the morphodynamics shows these differences can be essentially ascribed to the role of inertia of the solid particles

two dimensional two phase depth integrated model for transients over mobile bed

AbstractFast geomorphic transients may involve complex scenarios of sediment transport, occurring near the bottom as bed load (i.e., saltating, sliding, and rolling) or as suspended load in the upper portion of the flow. The two sediment transport modalities may even coexist or alternate each other during the same event, especially when the shear stress varies considerably. Modeling these processes is therefore a challenging task, for which the usual representation of the flow as a mixture may result in being unsatisfactory. In the present paper, a new two-phase depth-averaged model is presented that accounts for variable sediment concentration in both bed and suspended loads. Distinct phase velocities are considered for bed load, whereas the slip velocity between the two phases is neglected in the suspended load. It is shown that the resulting two-phase model is hyperbolic, and the analytical expression of the eigenvalues is provided. The entrainment/deposition of sediment between the bottom and the bed ..

ACEWATER2 Regional database: hydro-climatology data-analysis

The report presents the architecture of a regional hydro-climatology information system, developed in the framework of the ACEWATER2 project, in order to support effective organization of information. Information includes both freely available large and regional scale data sources, as well as databases compiled by the CoEs (Centers of Excellence) and submitted as part of their scientific undertakings. The information system builds upon and specializes the JRC knowledge sharing platform Aquaknow (https://aquaknow.jrc.ec.europa.eu/), including: • at the system core, a relational database; its schema has been designed to store both detailed metadata and, where relevant (avoiding duplication of information otherwise accessible), data themselves. Metadata include, among others, datasets extended description, spatial extent, temporal frequency, reference Institutions/authors, credits and limitations, web links to access original data and/or any further documentation. Data can be stored as public or private, depending upon confidentialy and sharing policies; • user friendly facilities, supporting the end user in efficiently browsing, querying, uploading and downloading information (metadata and data). System access is limited to accredited audience, via password authentication. Dedicated groups for the three ACEWATER CoE networks (Western, Southern and Central-Eastern Africa) have been setup and scientists invited to register. Currently the system is operational and we submitted databases documented and, depending upon confidentiality and authorization issues, also stored. A general review and classification of freely available information at continenal, regional and local scale of interest to ACEWATER2 project, and particularly to selected study areas (Senegal, Gambia and Niger; Zambezi; Blue Nile and Lake Victoria), have been completed. Metadata and, where relevant, data themselves have been stored to the information system database. Information submitted by the CoE (a continuous ongoing process) is migrated to the database as well, depending upon sharing authorization and/or limitations. The report also documents the ongoing scientific research at JRC on climate variability analysis based on L-Moments statistics. In particular maps of estimated precipitation deficit for different return periods at the river basins of interest are presented and included in the database.JRC.D.2-Water and Marine Resource

Genetic and Environmental Influences on Female Sexual Orientation, Childhood Gender Typicality and Adult Gender Identity

Background: Human sexual orientation is influenced by genetic and non-shared environmental factors as are two important psychological correlates – childhood gender typicality (CGT) and adult gender identity (AGI). However, researchers have been unable to resolve the genetic and non-genetic components that contribute to the covariation between these traits, particularly in women. Methodology/Principal Findings: Here we performed a multivariate genetic analysis in a large sample of British female twins (N = 4,426) who completed a questionnaire assessing sexual attraction, CGT and AGI. Univariate genetic models indicated modest genetic influences on sexual attraction (25%), AGI (11%) and CGT (31%). For the multivariate analyses, a common pathway model best fitted the data. Conclusions/Significance: This indicated that a single latent variable influenced by a genetic component and common nonshared environmental component explained the association between the three traits but there was substantial measurement error. These findings highlight common developmental factors affecting differences in sexual orientation

BHPR research: qualitative1. Complex reasoning determines patients' perception of outcome following foot surgery in rheumatoid arhtritis

Background: Foot surgery is common in patients with RA but research into surgical outcomes is limited and conceptually flawed as current outcome measures lack face validity: to date no one has asked patients what is important to them. This study aimed to determine which factors are important to patients when evaluating the success of foot surgery in RA Methods: Semi structured interviews of RA patients who had undergone foot surgery were conducted and transcribed verbatim. Thematic analysis of interviews was conducted to explore issues that were important to patients. Results: 11 RA patients (9 ♂, mean age 59, dis dur = 22yrs, mean of 3 yrs post op) with mixed experiences of foot surgery were interviewed. Patients interpreted outcome in respect to a multitude of factors, frequently positive change in one aspect contrasted with negative opinions about another. Overall, four major themes emerged. Function: Functional ability & participation in valued activities were very important to patients. Walking ability was a key concern but patients interpreted levels of activity in light of other aspects of their disease, reflecting on change in functional ability more than overall level. Positive feelings of improved mobility were often moderated by negative self perception ("I mean, I still walk like a waddling duck”). Appearance: Appearance was important to almost all patients but perhaps the most complex theme of all. Physical appearance, foot shape, and footwear were closely interlinked, yet patients saw these as distinct separate concepts. Patients need to legitimize these feelings was clear and they frequently entered into a defensive repertoire ("it's not cosmetic surgery; it's something that's more important than that, you know?”). Clinician opinion: Surgeons' post operative evaluation of the procedure was very influential. The impact of this appraisal continued to affect patients' lasting impression irrespective of how the outcome compared to their initial goals ("when he'd done it ... he said that hasn't worked as good as he'd wanted to ... but the pain has gone”). Pain: Whilst pain was important to almost all patients, it appeared to be less important than the other themes. Pain was predominately raised when it influenced other themes, such as function; many still felt the need to legitimize their foot pain in order for health professionals to take it seriously ("in the end I went to my GP because it had happened a few times and I went to an orthopaedic surgeon who was quite dismissive of it, it was like what are you complaining about”). Conclusions: Patients interpret the outcome of foot surgery using a multitude of interrelated factors, particularly functional ability, appearance and surgeons' appraisal of the procedure. While pain was often noted, this appeared less important than other factors in the overall outcome of the surgery. Future research into foot surgery should incorporate the complexity of how patients determine their outcome Disclosure statement: All authors have declared no conflicts of interes

Analysis of Bedform Instability with 1-D Two-phase Morphodynamical Models

The paper explores the possibility of predicting the occurrence of antidunes in gradually-varied flows through non-equilibrium morphological models natively derived, under the long-wave approximation, for fast geomorphic transients. Starting from a recent two-phase gradually-varied flow model, an improved version, which partially accounts for the bottom curvature effects, is proposed and analyzed. The normal mode analysis carried out on the linearized gradually-varied flow model shows the existence of unstable conditions at moderate Froude numbers characterized by bed perturbations migrating in the upstream direction. However, a proper wavelength selection may be obtained only when the bottom curvature is accounted for. Direct numerical simulations in linear regime of the improved model indicate the existence of unstable dominant wavelengths, which comply with experimental evidences. Full non-linear simula- tions confirm the ability of the improved two-phase model in predicting the antidunes formation