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Attribution of an extreme magnitude I-day rainfall event in Hobart is inhibited by small sample size. For moderate magnitude Hobart daily rainfall extremes, models suggest that the associated extratropical lows [...]

During mid-June to mid-July 2018, parts of Sichuan, Gansu, and Shaanxi provinces in China were affected by a persistent heavy rainfall event. Accumulated rainfall during the four-week period 18 June [...]

Category 4 landfalling hurricane Harvey poured more than a metre of rainfall across the heavily populated Houston area, leading to unprecedented flooding and damage. Although studies have focused on the contribution of anthropogenic climate change to this extreme rainfall event.sup.1-3, limited attention has been paid to the potential effects of urbanization on the hydrometeorology associated with hurricane Harvey. Here we find that urbanization exacerbated not only the flood response but also the storm total rainfall. Using the Weather Research and Forecast model--a numerical model for simulating weather and climate at regional scales--and statistical models, we quantify the contribution of urbanization to rainfall and flooding. Overall, we find that the probability of such extreme flood events across the studied basins increased on average by about 21 times in the period 25-30 August 2017 because of urbanization. The effect of urbanization on storm-induced extreme precipitation and flooding should be more explicitly included in global climate models, and this study highlights its importance when assessing the future risk of such extreme events in highly urbanized coastal areas.Modelling the contribution of urbanization to the impacts associated with hurricane Harvey in August 2017 shows that urbanization worsens rainfall and flooding., Author(s): Wei Zhang [sup.1] , Gabriele Villarini [sup.1] , Gabriel A. Vecchi [sup.2] [sup.3] , James A. Smith [sup.4] Author Affiliations:(1) IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, [...]

A system that involves the use of a low-cost microelectromechanical system (MEMS)-based sensor stick and soil-water characteristic curve (SWCC) inferred from grain-size distribution was developed to assess the factor of safety against rainfallinduced shallow slope failure. The system allows water content at multiple depths to be monitored in the field. The corresponding suction and factor of safety against infinite slope failure are derived based on the estimated SWCC. The new system circumvents the use of tedious and often costly field as well as laboratory procedures while providing a quantitative slope stability assessment on a real-time basis. The paper introduces the background of the new development and describes the application of the sensor stick system in a field test. Key words: unsaturated soil, slope failure, soil-water characteristics curve, microelectromechanical system (MEMS), real-time monitoring. Un systeme impliquant l'utilisation d'un capteur a base de systeme microelectromecanique (MEMS) et d'une courbe caracteristique de l'eau du sol (SWCC) deduite de la distribution granulometrique a ete developpe pour evaluer le facteur de securite contre les glissements de pente faible, induites par la pluie. Le systeme permet de surveiller la teneur en eau a plusieurs profondeurs sur le terrain. La succion et le facteur de securite correspondant contre un glissement de pente infinie sont calcules sur la base de la valeur SWCC estimee. Le nouveau systeme permet de contourner l'utilisation de procedures fastidieuses et souvent couteuses, ainsi que de procedures de laboratoire, tout en fournissant une evaluation quantitative de la stabilite des pentes en temps reel. La recherche presente le contexte du nouveau developpement et decrit l'application du systeme de capteurs dans un test sur le terrain. [Traduit par la Redaction] Mots-cles: sol non sature, glissement de pente, courbe caracteristique de l'eau du sol, systeme microelectromecaniques (MEMS), surveillance en temps reel., Introduction Rainfall has been considered as one of the most frequent triggering factors to natural slope failures (De Vita and Reichenbach 1998). It is well recognized that field hydrological and [...]

Upland rice fields cover up to 1.8 million hectares of the 4.7 million hectares of global rice fields, while farmers' average yield of upland rice is far below the yield potential of existing traditional genotypes, particularly in West Africa. Grain yields of rice in Liberia are generally low, ranging from 0.5-1.5 tons per hectare (t/ha). A field study was conducted to evaluate yield and agronomic performances of four genotypes of rice (Nerica 8, Nerica 4, Arica 5 and LAC 23) on a typical fine sandy loam soil in the upper highland tropical forest agro-ecological Zone (UHTF AZ) of Liberia. The Randomized Complete Block Design (RCBD) was used with four replicates in four blocks. Data were taken on key agronomic characters including plant height; days to 50% flowering; number of tillers; number of panicles; grain weight; panicle length; number of grains per plant; seed length and stem diameter at the base. Results from the Analysis of Variance (ANOVA) indicated that there were significant differences between the control (Lac 23) and the improved genotypes (Nerica 8, Arica 5 and Nerica 4) for all characters measured except for panicle length, seed length and stem diameter. Correlation analysis was also performed to establish extent of association between major yield components and grain yield. Days to 50% flowering correlated significantly with plant height, number of tillers and number of panicles per plant. Nerica 8, Arica 5 and Nerica 4 recorded the highest yield and may, therefore, be recommended to smallholder farmers in the upper highland forest zone. Lac 23, Arica 5 and Nerica 8 may be recommended for local farmers, who prefer high yielding, and relatively medium heighted improved rice cultivars or their interspecific hybrids. This is because extremely tall rice genotypes are susceptible to lodging, particularly in stormy conditions that are prevalent in the upper highland tropical forest agro-ecological zone of Liberia. Other approaches may be required to test these cultivars under harsh environments (such as water deficit condition) and different agro-ecologies across the country. We also recommend organoleptic assessments of Nerica 4, Nerica 8 and Arica 5 to boost their acceptability among consumers in the country.Key words: Upland rice, agronomic performance, improved genotypes, Nerica, correlation, Liberia, INTRODUCTIONRice consumption in West Africa has more than doubled in the last decade due to population growth and changing consumer dietary preferences [1]. Adoption of agronomic practices is critical for [...]

This paper presents a coupled air-water flow analysis to evaluate the performance of a three-layer capillary barrier for controlling water infiltration into and gas emission from a waste containment system in a high precipitation environment, and to optimize combinations of local soil layers for barrier construction. A multi-phase flow model is proposed considering the movements of the gas and water phases simultaneously. The governing partial differential equations are solved in COMSOL Multiphysics software. Several combinations of lean clay with sand (CL), clayey sand with gravel (SC), silty sand with gravel (SM), sandy silt (ML), and well-graded gravel with silt (GW-GM) are examined. The rates of percolation water and gas emission are used as indicators to compare the performance of different combinations. A fine-grained surface soil layer reduces both water infiltration and gas emission due to its low desaturation rate and high water-retention capacity. The coarse middle layer plays a critical role, promoting capillary effects and hindering water infiltration during rainfall as well as draining any infiltrated water or percolated gas. Key words: landfill, capillary barrier, rainfall infiltration, multi-phase flow, unsaturated soil. Cet article presente une analyse couplee du debit air-eau pour evaluer la performance d'une barriere capillaire a trois couches pour controler l'infiltration d'eau et les emissions de gaz provenant d'un systeme de confinement des dechets dans un environnement a fortes precipitations et pour optimiser les combinaisons de couches locales de sol dans le cadre de construction de la barriere. Un modele d'ecoulement polyphasique est propose en tenant compte des mouvements de la phase gazeuse et de la phase aqueuse simultanement. Les equations differentielles partielles principales sont resolues dans le logiciel COMSOL Multiphysics. On examine plusieurs combinaisons d'argile maigre avec du sable (CL), de sable argileux avec du gravier (SC), de sable limon avec du gravier (SM), de limon sablonneux (ML) et de gravier bien cale avec du limon (GW-GM). Les taux d'eau de percolation et les emissions de gaz sont utilises comme indicateurs pour comparer les performances de differentes combinaisons. Une couche de sol de surface a grain fin reduit a la fois l'infiltration d'eau et les emissions de gaz en raison de son faible taux de desaturation et de sa grande capacite de retention d'eau. La couche mediane grossiere joue un role critique, favorise les effets capillaires et entrave l'infiltration d'eau pendant les precipitations et evacue toute eau infiltree ou gaz percole. [Traduit par la Redaction] Mots-cles: decharge, barriere capillaire, infiltration de precipitations, ecoulement polyphasique, sol insature., Introduction Covers are widely used to control water infiltration into waste containments and tailings (Li et al. 2013). Traditional covers use materials with low permeability, such as compacted clays and [...]

Rainfall and reservoir water level fluctuations are the main external factors of landslides in the Three Gorges Reservoir area. To improve the analysis of slope stability under the combined effect of reservoir water level fluctuations and rainfall, a simplified method for phreatic line calculation of slopes is proposed in this study. Based on the obtained phreatic line, the expression of normal stress on the sliding surface of the slope under the hydrodynamic forces is deduced, and a global analysis method to solve the slope safety factor under hydrodynamic force is proposed. Finally, the safety evolution of a slope in the Three Gorges Reservoir area is studied under the combined effect of reservoir water level fluctuations and rainfall. Key words: slope, landslide, phreatic line, reservoir water level fluctuations, rainfall. Les fluctuations du niveau des eaux pluviales et des reservoirs sont les principaux facteurs externes des glissements de terrain dans la zone du reservoir des Trois Gorges. Afin d'ameliorer l'analyse de stabilite des talus sous l'effet des fluctuations combines de niveau d'eau de reservoir et de la pluie, une methode simplifiee pour le calcul de la ligne de la nappe phreatique des pentes est proposee dans cette etude. Base sur la ligne phreatique obtenue, l'expression de la contrainte normale sur la surface de glissement de la pente sous les forces hydrodynamiques est deduite, et on propose une methode d'analyse globale pour resoudre les coefficients de securite de la pente sous une force hydrodynamique. Enfin, l'evolution de la securite d'une pente dans la region du reservoir des Trois Gorges est etudiee sous l'effet combine des fluctuations de niveau d'eau de reservoir et de la pluie. [Traduit par la Redaction] Mots-cles : pente, glissement de terrain, ligne de nappe phreatique, fluctuations de niveau d'eau de reservoir, pluie., Introduction From the previous literature on landslides, rainfall is a main triggering factor to induce landslides in the Three Gorges Reservoir area (Yin et al. 2012; Sun et al. 2016a). [...]

The stability of cut slopes is greatly influenced by seasonal pore-water pressure variations under the combined effect of rainfall and vegetation. However, predicting soil-atmosphere interaction is not straightforward, due to the complexity of both the boundary conditions involved and the hydromechanical behaviour of soils, which is coupled and highly nonlinear, rendering the use of numerical tools, such as finite element analysis, necessary. This paper discusses the numerical modelling of soil-atmosphere interaction and presents the analysis of a slope cut in London clay in a highly vegetated area. The whole life cycle of the slope is considered with phases of low and high water demand vegetation and vegetation clearance. The analysis results indicate that dense vegetation is associated with high factors of safety, but may induce large differential displacements, which are likely to affect the serviceability of the slope. Vegetation clearance, however, may initiate instability, highlighting the need for effective vegetation management to achieve a balance between serviceability and ultimate limit states. Although the case considered is representative of southeast England, it introduces the necessary tools for realistic numerical analysis of soil-atmosphere interaction. Key words: slope stability, serviceability, vegetation, precipitation, soil-atmosphere interaction. La stabilite des pentes entaillees est fortement influencee par les variations de pression de l'eau interstitielle saison nieres sous l'effet combine des precipitations et de la vegetation. Cependant, predire l'interaction sol-atmosphere n'est pas si simple, en raison de la complexite des deux conditions aux limites en cause et le comportement hydromecanique des sols, qui est couple et fortement non lineaire, ce qui rend l'utilisation d'outils numeriques, tels que l'analyse des elements finis neces saire. Cet article traite la modelisation numerique de l'interaction sol-atmosphere et presente l'analyse d'une pente entaillee dans l'argile de Londres dans une zone tres vegetalisee. L'ensemble du cycle de vie de la pente est considere avec des phases de demande en eau basse et haute de la vegetation et la clairance de la vegetation. Les resultats de l'analyse indiquent que la vegetation dense est associee a des facteurs eleves de securite, mais peut induire des deplacements differentiels qui sont susceptibles d'affecter l'etat de fonctionnement de la pente. L'enlevement de la vegetation, cependant, peut declencher l'instabilite, soulignant la necessite d'une gestion efficace de la vegetation afin de parvenir a un equilibre entre la fonctionnalite et les etats limites ultimes. Bien que le cas considere est representatif du Sud est de l'Angleterre, il presente les outils necessaires a l'analyse numerique realiste de l'interaction sol-atmosphere. [Traduit par la Redaction] Mots-cles: stabilite des pentes, facilite d'entretien, vegetation, precipitations, interaction sol-atmosphere., Introduction It has long been established that one of the main factors affecting the performance of infrastructure slopes (cut and embankment slopes) is the magnitude and variation of pore-water pressures [...]

Author(s): Mahyar Mohtadi (corresponding author) [1]; Matthias Prange [1]; Stephan Steinke [1] Monsoons are the dominant seasonal mode of climate variability in the tropics and are critically important conveyors of [...]

The Amazon rainforest is crucial in regulating the global climate system, recycling water vapor from the Atlantic Ocean, and transporting heat and moisture from the tropics to the subtropics. During [...]

Author(s): Jian Wang (corresponding author) [1]; Radovan Krejci [2]; Scott Giangrande [1]; Chongai Kuang [1]; Henrique M. J. Barbosa [3]; Joel Brito [3]; Samara Carbone [3]; Xuguang Chi [4, 5]; [...]