河南省空中水汽资源的来源、分布及收支

利用1971-2005年河南省及其临近地区NCEP/NCAR月平均再分析资料和同期降水观测资料,分析了河南省空中水汽来源、水汽资源的时空分布、水汽输送特征以及河南省域水汽收支状况.结果表明:不同季节水汽来源、水汽通量强度及其随高度的分布、水汽通量散度等特征有相当大的差异;河南省空中年水汽含量平均值为25.79 mm,水...     

下击暴流实例分析

通过实地灾情调查,本文提供了一个证据较为充分、说服力较强的下击暴流实例,加深了人们对下击暴流的感性认识。实践证明,在观测密度(时间和空间上)远不能满足中小尺度分析要求、探测手段受到很大限制的情况下,用实地灾情调查和地面拍照的办法进行下击暴流这类中小尺度系统的分析是可行的。     

中国数字地震台网的建设与发展

地震台站作为地震系统基础单元,是设置地震监测设施并开展地震监测的基层机构,完备的地震监测设施和良好的地震观测环境是地震观测的基础。掌握完整、准确的地震台站基础信息是做好地震台站管理的关键。由于观测手段更新、观测环境变迁和建设条件差异的原因,投入运行后的地震台站基础信息与规划设计有偏差,一定程度上影响地震观测数据的准确性和有效性。本文论述了地震台站基础信息完善的意义,通过实例说明准确、有效的地震台站基础信息,在地震观测干扰排查、观测环境保护和台站升级改造方面的应用,旨在引起行业重视地震台站基础信息的收集、管理和应用,进而确保地震观测数据科学有效。     

Size and spatial distribution of loess slides on the Chinese Loess Plateau

ABSTRACT

The size and spatial distribution of loess slides are important for estimating the yield of eroded materials and determining the landslide risk. While previous studies have investigated landslide size distributions, the spatial distribution pattern of landslides at different spatial scales is poorly understood. The results indicate that the loess slide distribution exhibits a power-law scaling across a range of the size distribution. The mean landslide size and size distribution in the different geomorphic types are different. The double Pareto and inverse gamma functions can coincide well with the empirical probability distribution of the loess slide areas and can quantitatively reveal the rollover location, maximum probability, and scaling exponents. The frequency of loess slides increases with mean monthly precipitation. Moreover, point distance analysis showed that > 80% of landslides are located < 3 km from other loess slides. We found that the loess slides at the two study sites (Zhidan and Luochuan County) in northern Shaanxi Province, China show a significant clustered distribution. Furthermore, analysis results of the correlated fractal dimension show that the landslides exhibit a dispersed distribution at smaller spatial scales and a clustered distribution at larger spatial scales.     

Predicting the dependency of a degree of saturation on void ratio and suction using effective stress principle for unsaturated soils

The paper presents an approach to predicting variation of a degree of saturation in unsaturated soils with void ratio and suction. The approach is based on the effective stress principle for unsaturated soils and several underlying assumptions. It focuses on the main drying and wetting processes and does not incorporate the effects of hydraulic hysteresis. It leads to the dependency of water retention curve (WRC) on void ratio, which does not require any material parameters apart from the parameters specifying WRC for the reference void ratio. Its validity is demonstrated by comparing predictions with the experimental data on four different soils taken over from the literature. Good correlation between the measured and predicted behaviour indirectly supports applicability of the effective stress principle for unsaturated soils. Copyright © 2009 John Wiley & Sons, Ltd.