Influence of thawed soil depth on rainfall erosion of frozen bare meadow soil in the Qinghai–Tibet Plateau

The Qinghai–Tibet Plateau has a vast area of approximately 70×10⁴ km² of alpine meadow under the impacts of soil freezing and thawing, thereby inducing intensive water erosion. Quantifying the rainfall erosion process of partially thawed soil provides the basis for model simulation of soil erosion on cold-region hillslopes. In this study, we conducted a laboratory experiment on rainfall-induced erosion of partially thawed soil slope under four slope gradients (5, 10, 15, and 20°), three rainfall intensities (30, 60, and 90 mm h⁻¹), and three thawed soil depths (1, 2, and 10 cm). The results indicated that shallow thawed soil depth aggravated soil erosion of partially thawed soil slopes under low hydrodynamic conditions (rainfall intensity of 30 mm h⁻¹ and slope gradient ≤ 15°), whereas it inhibited erosion under high hydrodynamic conditions (rainfall intensity ≥ 60 mm h⁻¹ or slope gradient > 15°). Soil erosion was controlled by the thawed soil depth and runoff hydrodynamic conditions. When the sediment supply was sufficient, the shallow thawed soil depth had a higher erosion potential and a larger sediment concentration. On the contrary, when the sediment supply was insufficient, the shallow thawed soil depth resulted in lower sediment erosion and a smaller sediment concentration. The hydrodynamic runoff conditions determined whether the sediment supply was sufficient. We propose a model to predict sediment delivery under different slope gradients, rainfall intensities, and thawed soil depths. The model, with a Nash–Sutcliffe efficiency of 0.95, accurately predicted the sediment delivery under different conditions, which was helpful for quantification of the complex feedback of sediment delivery to the factors influencing rainfall erosion of partially thawed soil. This study provides valuable insights into the rainfall erosion mechanism of partially thawed soil slopes in the Qinghai–Tibet Plateau and provides a basis for further studies on soil erosion under different hydrodynamic conditions.     

塔里木盆地北部油气运移二维二相数值模拟分析

油气运移和聚集过程实际上是油（气）水饱和度知疏导层的变化过程，盆地中油（气）二相流动问题的研究就是对这一过程的定量描述，本项研究是在前人工作基础上，考察压实作用造成骨架变形来推导新的二维二相流动方程，它容描述异常压力演化与二相流动于一式，在模拟方法上采用有限分析的数值方法，这应用于新疆塔里木盆地北部地区，展示了该区异常压力、含水饱和度弥散状扩散效应以及流速场在地质历史时期动态模拟演化特征；指出了该     

Temporal vP/vS variation characteristics in different zones of China’s Capital Circle area before and after Wen’an earthquake

On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002~2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of restrictions on the computation environment and condition, e.g., the earthquakes are densely concentrated, selected stations are limited in range, the number of stations in- volved in the computation is larger than 5 and linear fitting features high precision and small error. Under these restrictions, the study shows that vP/vS in and around Wen’an and Tangshan underwent a normal-low-normal proc- ess one year before Wen’an earthquake, vP/vS became obviously low and the low ratio lasted for about one year, meanwhile, little variation of vP/vS was seen in Xingtai, northwest of Beijing, southwest of Beijing, Beijing-Tianjin and Beijing; after the quake, the vP/vS returned normal in Wen’an and Tangshan. Error and stability analysis of the calculated result for vP/vS shows it is convincible that anomaly appeared in and around Wen’an and Tangshan be- fore Wen’an earthquake.     

Morphometric analysis of a subtropical Andean basin (Tucumán, Argentina)

A morphometric analysis was done to determine the drainage characteristics of Lules River basin using land-sat imageries and topographical maps. This catchment was divided into seven sub-basins for the analysis: Liquimayo, Hoyada, Ciénaga, De Las Tablas, Siambón, Potrerillo and San Javier. Yungas ecoregion covers almost all the watershed. The drainage patterns of the sub-basins are dendritic and parallel. The basin includes seventh order stream and lower streams order mostly dominate the basin. The development of stream segments is affected by slope and local relief. The mean bifurcation ratio indicates that the drainage pattern is not much influenced by geological structures. The shape parameters also reveal the elongation of the basin and sub-basins.     

Meteorological Office, Pune-411 005

Natural disasters like floods, tornadoes, tropicalcyclones, heat and cold wavewreak havoc and cause tremendous loss ofproperty all over the world. Most ofthe natural disasters are either dueto weather or are triggered due toweather related processes.Extreme weather events claimed thousands oflives and caused damage on vastscale. Recent super cyclone which affectedOrissa in 1999, Bangladesh cyclone of1970 and Hurricane Andrew in 1992 areexamples of some of the more damagingtropical cyclones which affected developingas well as the developed world. Heatand cold waves are also extreme events,which cause enormous losses in terms oflives lost and human discomfort and ailmentsarising out of them. The heat waveof 1995 and 1998 are still fresh in the mindof the Indian public. The estimated lossof human lives due to heat wave in 1998 was morethan 15,000. Economic losses asa result of these disasters and in particular inassociation with tropical cyclones haveincreased enormously over the last three decades.During 1961–1991, total loss oflives from drought alone was 1,333,728 overthe whole world. In terms of economiclosses, there is 8–10 fold increase from thebase figure of 1960. The socio-economicimpact of natural disaster is complex dependingupon the vulnerability of the placeand mitigation strategies that are put in place.Meteorology plays a crucial role in forewarningpeople about the severe/extremeweather systems and a constant endeavour by themeteorological services worldover has gone a long way towards minimizing thelosses caused by natural disasters.The paper summarises the natural disasterstatistics over south Asia and the possibleprediction strategies for combating theirsocio-economic impacts.     

河南西峡白垩纪地层和蛋化石

本文在对西峡地区恐龙蛋化石分布进行全面评价同时,还首次报道了鳄类蛋化石、鸟类蛋化石、赵营组的无脊椎动物化石,这些新发现不仅丰富了西峡地区生物群面貌,也揭示了伏牛山南麓白垩纪构造盆地特点.     

A comparative study of four vulnerability mapping methods in a detritic aquifer under mediterranean climatic conditions

This paper presents the results of a comparative study relating to the application of four vulnerability mapping methods, GOD, AVI, DRASTIC and SINTACS, in a pilot detritic aquifer situated in NW Morocco, known as the Martil–Alila aquifer. The principal objective of this work is to determine the most suitable such methods for this aquifer type within a Mediterranean context, and to show the effect of the rainfall variations that are characteristic of the Mediterranean climate on the degree of vulnerability. The methods applied distinguish five classes of vulnerability, these being irregularly divided up in space, with the division varying according to the method in question. The vulnerability maps obtained by the different methods strongly suggest that the eastern half of the aquifer is more vulnerable to contamination than the western half, for all hydrological situations. The effect of climatic conditions on the degree of vulnerability is well represented by the DRASTIC, according to which the aquifer is moderately to strongly vulnerable during humid hydrological years and weakly to moderately vulnerable during dry ones. For the other methods, this climatic effect is limited to the area occupied by the two predominant classes (“High” and “Low” for GOD and “High” and “Moderate” for SINTACS) while it is null for AVI. In conclusion, DRASTIC appears the most suitable for mapping the vulnerability to contamination of Mediterranean coastal detritic aquifers such as the Martil–Alila aquifer.     

Zircon U-Pb dating of intermediate-acid intrusive rocks in the middle section of Ningzhen district and their metallogenic implicationsEI北大核心CSCD

The Ningzhen metallogenic district is an important part of the Middle-Lower Yangtze River Valley metallogenic belt. LA-ICP-MS zircon U-Pb dating of the three intermediate-acid intrusions, i.e., Anjishan, Xinqiao, and Shima, in the central part of the Ningzhen district, indicates that those intrusions were emplaced in the Late Early Cretaceous, with ages of 107.0±1.1 Ma-108.0±1.6 Ma, 108.0±1.3 Ma, and 102.5±1.1 Ma, respectively. Combined with the molybdenite Re-Os isotope age (106-108 Ma) of porphyry copper deposit in this regions, the Ningzhen district exists an intensively magmatic-metallogenic-thermal event at 102.5-108.0 Ma. The age of this event is similar with the age of the third period of large scale mineralization in South China, however obviously later than the magmatic activity of other ore field (124-148 Ma) in the Middle-Lower Yangtze River Valley metallogenic belt. It is suggested that the tectonic-magmatic-thermal events in the Ningzhen area is formed under regional lithospheric extension environment, which is also consistent with the tectonic background of the third period of large scale mineralization in South China. The zircon U-Pb ages of the intrusions and the Re-Os ages of molybdenites from the porphyry deposits in the study area demonstrate that the Ningzhen district underwent intensive magmatism and hydrothermal mineralization during the period from 102.5 to 108.0 Ma, which is consistent with the third pulse of large scale mineralization in the South China. ©, 2015, Science Press. All right reserved.     

Petrogenesis of the Late Cenozoic collision volcanism in the central part of the Lesser Caucasus (Azerbaijan)

The Late Cenozoic volcanics of the Lesser Caucasus have similar trace-element and REE patterns with negative anomalies of Nb, Ta, Hf, and Zr. They are highly enriched in Rb, Ba, Th, and La and depleted in Ti, Yb, and Y with respect to N-MORB, which indicates their formation from the subduction-metasomatized lithospheric mantle. Partial melting of the subcontinental mantle lithosphere and crustal assimilation and fractional crystallization controlled the magma evolution in the collisional magmatic belts.     

High parallelization efficiency in barotropic-mode computation of ocean models based on multi-grid boundary ghost area

In general, barotropic-mode computation requires the largest communication time in ocean models because of its iterative nature, when parallel computation is performed based on regional partitioning. In this study, reduction in the overhead time included in the communication in the parallel computation of the barotropic mode is considered to achieve a high parallelization efficiency of ocean models. We verify that the reduction in the communication frequency based on the multi-grid boundary ghost area reduces the total communication time. We find that this is because the sum of several kinds of overhead time for communication occupies a fairly large part of the total communication time. We discuss the trade-off between the decrease in communication time and the increase in computation time due to increased boundary area in such cases, leading to a determination of a suitable width of the multi-grid boundary that minimizes the total required time. We also discuss the efficiencies of the one- and two-dimensional partitioning of the model domain, when a multi-grid boundary is used. In general, two-dimensional partitioning is more efficient than one-dimensional for large partitioning numbers.