Projected changes in meteorological drought over East Africa inferred from bias-adjusted CMIP6 models

Natural Hazards - The ongoing global warming has caused unprecedented changes in the climate system, leading to an increase in the intensity and frequency of weather and climate extremes. This...     

Correction to: Imagery of the metamorphic bedrock roof of the Sahel active fault in the Sablettes (Algiers) reclaimed area by ambient vibration HVSR

The original version of this paper was published with incomplete affiliation. Given in this article are the complete affiliations.     

Modelling the effect of temperature on unsaturated soil behaviour

A simple thermohydromechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way.     

Energy fluxes and melt rate of a seasonal snow cover in the Moroccan High Atlas

ABSTRACT

In this study, we used an energy balance model and two simple methods based on readily available data to identify the processes driving the point-scale energy and mass balance of the snowpack. Data were provided from an experimental site located at 3200 m. All models were evaluated by comparing observed and modelled snow water equivalents. Performances are variable from one season to the next and the energy balance model gives better results (mean of root mean square error, RMSE = 25 mm and r² = 0.90) than the two simplified approaches (mean of RMSE = 54 mm and r² = 0.70). There are significant amounts of snow sublimation but they are highly variable from season to season, depending on wind conditions (between 7 and 20% of the total). While the main source of energy for melting is net radiation, the amount of heat brought by sensible heat flux is significant for two of the most windy snow seasons.

Editor Z.W. Kundzewicz Associate editor not assigned     

Imagery of the metamorphic bedrock roof of the Sahel active fault in the Sablettes (Algiers) reclaimed area by ambient vibration HVSR

The Sablettes (Algiers) coastal reclaimed fringe region, located on the hanging wall of the Sahel active fault, is subject to different types of geological hazard such as flood and tsunami, coastal uplift, earthquake, liquefaction, landslide, and site effects. In this present work, we used ambient vibration HVSR for imaging the bedrock. The thickness of the sedimentary column under the backfill layer is unknown, and the coastal reclaimed areas are prone to strong amplification of seismic waves. The determination of the depth of the metamorphic base allowed us to establish a mapping of the bedrock roof surface. The 3D representation of this surface enabled us to present models of tectonic structures in this basement (i.e., fault, fold). This analysis will make it possible to make better evaluation of the amplification after having determined the depth of the metamorphic basement exceeding 240 m, which is supposed to have velocities close to those of the seismological basement, as well as the thicknesses of the different layers surmounting it.     

Effective parameters of surface energy balance in heterogeneous landscape

This paper addresses the problem of estimating surface fluxes at large scale over heterogeneous terrain, and the corresponding determination of effective surface parameters. Two kinds of formulation are used to calculate the fluxes of sensible and latent heat: the basic diffusion equations (Ohm's law type) and the Penman-Monteith equations. The strategy explored is based upon the principle of flux conservation, which stipulates that the average flux over a large area is simply the area-weighted mean of the contributions from the different patches making up the area. We show that the application of this strategy leads to different averaging schemes for the surface parameters, depending on the type of flux (latent heat, sensible heat) and on the type of formulation used to express the flux. It appears that the effective value of a given parameter must be appraised for each individual application, because it is not unique, but differs according to the magnitude being conserved and the equation used to express this magnitude. Numerical simulations are carried out to test over contrasted areas the aggregation procedures obtained. The areal fluxes estimated from these effective parameters, together with the areal fluxes calculated by means of a simple areal averaging of the parameters, are compared to the true average fluxes, calculated as area-weighted means of the elementary fluxes. The aggregation procedures obtained prove to be much more accurate for estimating areal fluxes and for closing the energy balance equation than those based upon simple areal averaging of the parameters.     

Hepatic hemosiderosis in buffalo fish (Ictiobus spp.)

Hepatocellular hemosiderosis was observed in several species of fish associated with mixed chemical pollution in a Mississippi River Basin ecosystem. Three species of buffalo fish—smallmouth buffalo (Ictiobus bubalus), bigmouth buffalo (Ictiobus cyprinellus), and black buffalo (Ictiobus niger)—were collected from a contaminated site, Devil's Swamp, and a control site, Tunica Swamp, both near Baton Rouge, Louisiana. Liver, kidney and spleen were examined histologically. Hepatocellular iron overload was observed in smallmouth buffalo and bigmouth buffalo from Devil's Swamp. Smallmouth buffalo from Tunica Swamp had no stainable iron in the hepatocytes. Bigmouth buffalo from Tunica Swamp had trace amounts of stainable iron in the hepatocytes. Black buffalo from both Devil's Swamp and Tunica Swamp had no stainable iron in the hepatocytes. Iron could accumulate in sediment where it enters the food chain through benthic organisms. Analyses of water and sediment from both study sites revealed similarly high concentrations of iron. The pollutants in the Devil's Swamp may have affected the iron absorption and metabolism in smallmouth buffalo and bigmouth buffalo. The variation in the presence of stainable iron in the liver of three species of buffalo fish may indicate significant interspecies variation in the iron absorption and metabolism under conditions of mixed pollution.     

Improving the resilience of existing built assets to earthquake induced liquefaction disaster events

Bulletin of Earthquake Engineering - LIQUEFACT was a EU H2020 funded project to investigate earthquake induced liquefaction potential across Europe and develop a series of tools to understand...     

A thermo‐hydro‐mechanical model for unsaturated soils based on the effective stress concept

A simple thermo‐hydro‐mechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way. Copyright © 2010 John Wiley & Sons, Ltd.