Analysis of stability of earthen dams in kachchh region, Gujarat, India

The Kachchh region of Gujarat, India bore the brunt of a disastrous earthquake of magnitude M_w = 7.6 that occurred on January 26, 2001. The major cause of failure of various structures including earthen dams was noted to be the presence of liquefiable alluvium in the foundation soil. Results of back-analysis of failures of Chang, Tappar, Kaswati and Rudramata earth dams using pseudo-static limit equilibrium approach presented in this paper confirm that the presence of liquefiable layer contributed to lesser factors of safety leading to a base type of failure that was also observed in the field. Following the earthquake, earth dams have been rehabilitated by the concerned authority and it is imperative that the reconstructed sections of earth dams be reanalyzed. It is also increasingly realized that risk assessment of dams in view of the large-scale investment made and probabilistic analysis is necessary. In this study, it is demonstrated that the probabilistic approach when used in conjunction with deterministic approach helps in providing a rational solution for quantification of safety of the dam and in the estimation of risk associated with the dam construction.     

卫星单收站的正确安装和常见问题的解决方法

卫星单收站在地市气象局开通运行以来，取得了良好的业务效益。尤其它是地市级远程教育的系统平台，它的正常工作与否直接影响县级气象工作的业务成效。但随着使用时间的增长在技术保障方面也显露出诸多问题。我们在工作中总结了有关单收站安装的关键步骤、技术要求和多发故障的解决方法，希望能对基层台站的工作有所帮助。     

Distribution and reproductive behavior of penguins on Ardley Island and their environmental impact factors

During the 2006/07 Antarctic summer, the species population, distribution and reproductive behavior of penguins in areas near the Great Wall Station were investigated. Five species of penguin were recorded: gentoo penguin (Pygoscelis papua), adelie penguin (P. adeliae), chinstrap penguin (P. antarctica), King penguin (Aptenodytes patagonicus) and Emperor penguin (A. forsteri). The first three species bred locally, while the other two species were observed occasionally. Ardley Island is one of the most important breeding areas for penguins. After the breeding season of 2006/07, there were a total of about 17 234 penguins and the breeding success rate was 0.40-141. Comparing with historical data, changes in penguin species populations and distribution were analyzed, and their relationships with the environment, climate change and human activity were investigated.     

Responses of mud snails from low and high imposex sites to sex pheromones

Imposex, male secondary sexual characteristics in female snails, is a morphological indicator of sub-lethal exposure to organotin compounds. The relation between imposex and behavioral responses to sex pheromones was studied. Responses of snails to sex specific pheromones were determined in laboratory assays. Females and males from a low imposex site and females, imposex females and males from a high imposex site were tested. The snails from the low imposex site showed the expected strong behavioral dimorphism with females responding to male pheromone and males responding to female pheromone. In assays using snails from the high imposex site, female and imposex females showed no dimorphism in response to pheromones and males showed a relatively weak dimorphism. As there was no breeding or egg capsule deposition at the high imposex site, we conclude that even the morphologically normal snails were behaviorally and reproductively compromised.     

Slope stabilization and landslide size on Mt. 99 Peaks after Chichi Earthquake in Taiwan

The study focuses on the landslide characteristics of Mt. 99 Peaks in Nantou County, the most serious landslide prone area caused by Chichi Earthquake in Taiwan. Several investigations and field surveys were made on Mt. 99 Peaks for 5 years to research the landslide area and depth, rainfall trend, and slope stabilization. The total landslide volume caused by the earthquake on Mt. 99 Peaks was about 1.47×10⁶ m³ and the mean landslide thickness was about 0.22 m. Gravel layers with a volume of more than 80% of total soil profile dominated Mt. 99 Peaks. The landslide on Mt. 99 Peaks was induced by heavy rainfall from July to September because the rainfall on Mt. 99 Peaks had a nonuniform distribution in time. Although the vegetation recovery on Mt. 99 Peaks was in progress, the soil slope had remained unstable. As a result, Typhoon Mindulle occurred in July 2004 collapsed the hillslope again after 5 years of Chichi Earthquake. This study suggests that vegetation recovery on Mt. 99 Peaks for 5 years was insufficient to stabilize the landslide affected area.     

Breeding cycle of the red squat lobster Pleuroncodes monodon H. Milne Edwards, 1837 (Decapoda,Muninidae) from deepwater Pacific of Costa Rica

Reproduction and larval development of the red squat lobster Pleuroncodes monodon is strongly linked to temperature changes provoked by upwelling along the Chilean coast. Here, we propose the hypothesis that both the breeding cycle and the spatial distribution of egg‐bearing females of P. monodon in Costa Rica are related to decreasing water temperatures during seasonal coastal upwelling. To describe the breeding cycle, squat lobsters were collected between February 2007 and January 2008 from the Central Pacific coast of Costa Rica. The presence of egg‐bearing females in other areas of the Costa Rican coast was studied from samples collected during two latitudinal research cruises (August 2008: rainy season; May 2009: dry season). Our results revealed that P. monodon has a marked seasonal breeding period (from November to March), which is associated with decreasing water surface temperatures registered during coastal upwelling events. All females with embryos close to hatching were found in areas surrounding the Gulf of Nicoya, when upwelling events have been reported. The near absence of egg‐bearing females in zones where upwelling does not occur suggests the existence of a strong correlation between upwelling events and the breeding cycle of P. monodon. Our information should be considered when developing management measures for the sustainable use of this potential fishery resource in the Pacific coast of Central America.     

GRAPES-EPS系统的初值生成方法与对比试验研究

介绍了增长模繁殖法（BGM）和集合转化卡尔曼滤波法（ETKF）两种不同的模式初始扰动方法的基本原理,并以GRAPES中尺度模式为基础,利用两种初始扰动方法构建了两套中尺度集合预报系统。通过圣帕台风的个例试验,对比两种初始扰动生成方法对降水预报结果的影响。结果表明：两种方法均可以很好的捕捉到中尺度强降水的过程信息,集合平均结果优于控制预报,并在一定程度上改善了对强降水的落区和强度的预报;从邮票图和对集合预报系统的检验参数上来看,ETKF的集合离散度和特征值分布好于BGM方法,但对于降水结果TS等的评分的比较上来看,BGM的预报结果要优于ETKF的预报结果;另外,BGM方法和原理更简单,易于实现业务应用。