Formalized analysis of crustal seismicity in the Sikhote Alin orogen and adjacent areas

The fractal dimension of the epicentral field of earthquakes (D = 1.6) is determined for the Sikote Alin orogen and adjacent areas. According to this parameter, the region occupies the position between the Kamchatka Peninsula, Kuril Islands (1.61 and 1.69), the East China area, and the Lake Baikal region (1.55 and 1.40). Differentiation of the studied area based on the fractal dimension of the number of earthquakes and on the released energy calculated per unit square shows that the most active crustal areas are associated with the Kharpi–Kur–Priamur’e zone of the northeastern orientation, which is the northern segment of the Tan-Lu transregional fault system. Analysis of the time series of seismic events (MLH ≥ 2.4) in the Sikhote Alin and adjacent areas in the period from 1960 to 2013 shows that the “harmonic” with a 10.5-year period is most clearly displayed. This period (11–13 years) was previously distinguished by B.V. Levin and coauthors from the study of the largest number of earthquakes with M ≥ 4.4 for the period of 1971–2003.     

Measuring runoff by plots at different scales: Understanding and analysing the sources of variation

The decrease of runoff with the increase in area is not a new fact. The scale effect depends on the spatial and temporal variability of different factors, including the surface characteristics and hydrodynamic properties of the soil and the vegetation development. The purpose of our work is to study the relative influence of the sources of variation of runoff from a small Sahelian catchment on several types of soil surfaces features. Plots of different sizes (1, 50 and 150 m²) on cultivated soils and degraded soils (non-cultivated with three different types of crusts) were monitored for two consecutive years. The results show that the runoff coefficients of rainfall events range from 4 to 65% on cultivated soils and 16 to 96% on uncultivated bare and degraded soils. A statistical and dimensionless analysis shows that in degraded environments, the processes generating runoff on plots of 50 and 150 m² are identical and significantly different from the unit plot (1 m²). The decrease in runoff with increasing scale becomes more pronounced when rainfall duration decreases. In cultivated areas, this result is not observed. Additional measurements are needed to better understand the differences in functioning at various scales of observations.     

Nutrient load estimates for Manila Bay,Philippines using population data

A major source of nutrient load to periodically hypoxic Manila Bay is the urban nutrient waste water flow from humans and industries to surface water. In Manila alone, the population density is as high as 19,137 people/km². A model based on a global point source model by Morée et al. (2013) was used to estimate the contribution of the population to nitrogen and phosphorus emissions which was then used in a water transport model to estimate the nitrogen (N) and phosphorus (P) loads to Manila Bay. Seven scenarios for 2050 were tested, with varying degrees and amounts for extent of sewage treatment, and population growth rates were also included. In scenario 1, the sewage connection and treatment remains the same as 2010; in scenario 2, sewage connection is improved but the treatment is the same; in scenario 3, the sewage connection as well as treatment is improved (70% tertiary); and in scenario 4, a more realistic situation of 70% primary treatment achieved with 100% connection to pipes is tested. Scenarios 5, 6, and 7 have the same parameters as 1, 2, and 3 respectively, but with the population growth rate per province reduced to half of what was used in 1, 2, and 3. In all scenarios, a significant increase in N and P loads was observed (varying from 27% to 469% relative to 2010 values). This was found even in scenario 3 where 70% of the waste water undergoes tertiary treatment which removes 80% N and 90% P. However, the lowest increase in N and P load into the bay was achieved in scenarios 5 to 7 where population growth rate is reduced to half of 2010 values. The results suggest that aside from improving sewage treatment, the continued increase of the human population in Manila at current growth rates will be an important determinant of N and P load into Manila Bay.

     

Numerical Simulation of the Airflow Across Trees in a Windbreak

The flow across a three-dimensional (3-D) windbreak comprising individual cypress trees is studied to establish the significance and extent of the 3-D flow patterns. The cypress tree is modelled as a solid cylindrical stem and a conic porous canopy. Cases with a single row of trees or two rows of trees with different distances between the rows are considered; in the case of a single row, several densities of the canopy are used. The steady Reynolds-averaged Navier–Stokes (RANS) approximation is solved using a commercial computational fluid dynamics (CFD) package and a high-resolution mesh. Three-dimensional flow is found in the vicinity of the windbreak up to a leeward distance of 1–2 tree-heights, depending on the density of the canopy, and is manifest as significant lateral variations and reduced vertical flow. At larger leeward distances, a two-dimensional (2-D) flow is established with characteristics similar to existing 2-D studies; the flow leeward of the last row is insensitive to the distance between the rows. Homogeneous 2-D windbreak models are found to be inaccurate in the vicinity of the windbreak. This is exactly the region that needs to be sheltered in many cases, since the inner vegetation is anyway protected by the outer vegetation.     

Charmed meson pair production in high-energy pp collisions within the QCD color dipole approach

A study of double-charmed meson production in high-energy proton–proton collisions at the Large Hadron Collider is presented. Considering the color dipole formalism developed in the transverse momentum representation along with the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of -mesons. The theoretical results cover the center-of-mass energy and forward rapidities available by the LHCb experiment. The proton–proton results considering different unintegrated gluon distributions are compared to the respective data collected at the LHC.     

Influence du Bani sur la variabilité saisonnière et interannuelle de la crue du fleuve Niger dans le delta intérieur au Mali

Le delta intérieur du fleuve Niger est une zone humide sahélienne dont l’inondation dépend de la pluviométrie des bassins supérieurs du fleuve Niger et de son principal affluent, le Bani. La crise climatique qui a débuté en 1970 a très peu influencé les dates de passage des maximums de crue sur le Niger amont et son principal défluent, le Diaka. L’influence par contre est très forte sur le Bani, à la confluence avec le Niger à Mopti et sur le delta aval avec des dates de passages des maximums plus précoces qu’auparavant. Cela est dû à la faiblesse des superficies inondées au cours des années sèches. Pendant les années humides, l’importance des débordements latéraux ralentit la propagation de la crue avec pour conséquence des dates de passages plus tardives des maximums. Par ailleurs pendant les années humides antérieures à 1970 l’importance des débordements latéraux conférait au delta amont un caractère d’autorégulation par écrêtage des crues au niveau de certaines station.     

Une méthode de simulation de l'évolution des profils d'altération

Calculations of transfer of elements between minerals and aqueous solutions can be extended to water open systems. With this method, we can obtain steady state for water composition. Furthermore, evolution in space and time of a weathering profile can be computed.     

Intact ash and charred litter reduces susceptibility to rain splash erosion post‐wildfire

This paper describes the changes in soil water repellency and soil hydrological and erosional responses to rainfall at small‐plot scale, arising from a prescribed fire immediately following burning and one year later in a Mediterranean heathland in the area of the Strait of Gibraltar (southern Spain). Very little research has been carried out about the modifications on the ground surface after fire immediately after burning. A prescribed fire was conducted to study short‐term changes of the ground surface immediately and one year following burning. After a prescribed fire, a homogeneous charred litter layer and ash‐bed covered the mineral soil surface. This cover stayed stable on the soil surface during a period of seven days, until strong winds redistributed litter and ashes. The hydrophobicity of the exposed surface (litter and ashes) decreased considerably in relation with the litter layer properties before the fire. Ponding, runoff coefficients and soil loss were determined using simulated rainfall over the litter layer, the ash‐bed and the bare soil. Significant differences were not detected between pre‐ and post‐fire soil loss rates while a charred litter and thick ash layer were present on the ground surface. Runoff and erosion rates increased and time to ponding and runoff decreased when the charred litter and ash layers were artificially removed and the bare soil was exposed. Although wildfires will increase soil erodibility, the trends observed in this study suggest that this increased susceptibility to erosion from rainsplash processes may be limited to some degree while an intact ash and charred litter layer is still present. Copyright © 2009 John Wiley & Sons, Ltd.