金沙江干热河谷土地荒漠化评价指标体系研究

土地荒漠化的评价是土地荒漠化研究中的重要理论问题,根据多年对金沙江干热河谷土地荒漠化形成机制、影响因子及荒漠化土地的表现特征等的研究,提出了土地荒漠化评价的原则,并通过对各影响因子在土地荒漠中贡献率的分析和筛选,选择出能显著评价土地荒漠化程度的三个因子,五个指标,即地貌因子的切割密度和坡度,土壤因子的土壤厚度和有机质含量,植被因子的植被指数。在大量样方测算和样品分析的基础上给出每个指标的量化标准,首次建立了金沙江干热河谷土地荒漠化的评价指标体系。针对土地景观生态系统的复杂性和模糊性,在建立评价指标体系的基础上,采用模糊综合评判的方法,对土地荒漠化程度进行定量评价,为荒漠化土地的预防和治理提供科学依据和决策支持。     

The palaeo‐valley infilling glaciogenic Sarah Formation,an example from Rahal Dhab palaeo‐valley,Saudi Arabia

The Sarah Formation is a glaciogenic sedimentary unit deposited along the Gondwana margin during the latest Ordovician ice age and represents a major hydrocarbon reservoir in northern Saudi Arabia. Large‐scale glacial palaeo‐valleys cut into the Qasim Formation and were infilled by the Sarah Formation. Post‐glacial transgression in the earliest Silurian resulted in the deposition of the Qusaiba Shale Member and associated organic‐rich basal source rocks, which cap the Sarah Formation infilled palaeo‐valleys. This unique setting makes the Sarah Formation an important emerging exploration target in Saudi Arabia. This study focuses on the facies and depositional architecture in seismic‐scale outcrops of the Sarah Formation in north‐western Saudi Arabia. The Rahal Dhab palaeo‐valley provides a 100 km long dip‐oriented cross‐section which has been covered by 24 vertical sections, sedimentary architectural analyses at metre to kilometre scale and by three cored shallow boreholes. In the Rahal Dhab palaeo‐valley, the Sarah Formation was deposited in a proglacial setting that ranged from marginal marine to offshore prodelta and is made up of three units: (i) the Sarah Sandstone; (ii) the Sarah Shale; and (iii) the Uqlah Member. This study shows the relationships between these three units and architectural controls on reservoir quality in this system. This paper contributes to the regional understanding of the Sarah Formation, and the new depositional model of the Rahal Dhab palaeo‐valley provides an outcrop‐reservoir analogue for hydrocarbon exploration in adjacent areas.     

1998年夏季HUBEX/GAME期间热量和水汽收支(英)

By using the high-resolution GAME reanalysis data, the heat and moisture budgets during the period of HUBEX/GAME in the summer of 1998 are calculated for exploring the thermodynamic features of Meiyu over the Changjiang-Huaihe (CH) valley. During the CH Meiyu period, an intensive vertically-integrated heat source and moisture sink are predominant over the heavy rainfall area of the CH valley, accompanied by strong upward motion at 500 hPa. The heat and moisture budgets show that the main diabatic heating component is condensation latent heat released by rainfall. As residual terms, the evaporation and sensible heating are relatively small. Based on the vertical distribution of the heat source and moisture sink, the nature of the rainfall is mixed, in which the convective rainfall is dominant with a considerable percentage of continuous stratiform rainfall. There are similar time evolutions of the main physical parameters(〈Q1〉,〈Q2〉,and vertical motion ω at 500 hPa).The time variations of〈Q1〉and〈Q2〉are in phase with those of -ω500, and have their main peaks within the CH Meiyu period. This shows the influence of the heat source on the dynamic structure of the atmosphere. The wavelet analyses of those time series display similar multiple timescale characteristics. During the CH Meiyu period, both the synoptic scale(～6 days) and mesoscale (～2 days and ～12 hours) increase obviously and cause heavy rainfall as well as the appearances of the maxima of the main physical parameters. Among them, the mesoscale systems are the main factors.     

珠峰北坡绒布河谷局地环流的模拟分析

对珠峰北坡绒布河谷地区大气观测实验发现,绒布河谷中地面气流存在明显的日变化,但有别于其它地区的山谷风系统:在凌晨至正午前后基本为＜2m·s-1的小风,而午后至午夜则盛行来自珠峰方向的偏南下山风.由于珠峰北坡地区地形复杂,绒布河谷中地面气流的日变化可能是山谷风、坡风与冰川风等环流系统共同作用的结果.为了分析绒布河谷中风场日变化的主要驱动因子,本文利用一个中尺度气象模式对绒布河谷中典型风场进行了模拟,并借助观测资料对模拟结果进行了检验,进而对风场的时空分布特征及其变化原因进行了探讨.     

江淮地区旱涝时期大气潜热能和大气感热能的计算与比较

旱涝灾害的发生,追究其形成的物理原因,主要是由于地球和大气系统能量传输异常而导致水、热收支与循环变异所造成．本文选取江淮流域夏季出现洪涝和干旱年份的水、热资料,计算了江淮地区整层大气柱以及从地面到１５０ｈＰａ共分１０层的逐层大气的潜热能和感热能,对其的能量含量、能量输送量及能量源、汇（辐合、辐散量）作了时空分布特征的分析比较,探讨了旱涝形成的物理原因．     

GPS monitoring and new data on slope movements in the Maratea Valley (Potenza,Basilicata)

Large-scale earth movements in the Maratea valley involving the inhabited area (Basilicata, Italy) have already been the object of scientific studies. These dislocate the outcropping clayey formations and the superimposed masses made up of detritus, carbonate units and large blocks, especially on the left side of the valley. Initial data on earth movements were obtained by the variation in distances monitored by an infrared distance-meter instrument (EDM), between 1983 and 1996.The present study brings out the results obtained by three successive high precision GPS monitoring campaigns undertaken between 1997 and 2000, on a grid of approximately 50 bench-marks. This process was supplemented by EDM monitoring carried out on a wider network of bench-marks than previously imposed. A comparison of different maps and other historical measurements complete the picture.The presence of sustained movements in correspondence with the outcropping clays in the lower part of the valley was confirmed, while such movements are drastically reduced on the detritus and large dislocated carbonate units and blocks, which occupy almost uninterruptedly the left side and the upper parts of the valley. Overall, the arrangement of the vectors allows us to achieve a first model of the on-going gravitational processes in the valley which appear to be attributable to a composite landslide: a spreading evolving lower-down into a large and deep flow. These processes should affect the dislocation of Carbonate Units on the so-called Sackung of Maratea, whose instability and causes are still being studied.     

北京某景区崩塌灾害隐患点治理方案设计思路

山岳型风景名胜区地质灾害治理的难点在于将地质灾害隐患治理与当地自然风景相统一,既保留住景区的背景特色,又能彻底消除地质灾害的安全隐患。本文对北京怀柔某景区崩塌隐患点地质灾害特征进行了介绍,对隐患点危岩体（带）的稳定性进行了计算及评价,分析了地质灾害成因及发展趋势,最后对景区地质灾害治理的方法和思路进行了比选分析,选择了加固及避让的治理措施,摸索出经济、合理以及与景区风景相协调的治理方案,最大程度地保护了风景区的自然景观与自然资源,可以为相关地质灾害治理提供参考借鉴。     

EH4电磁系统的近源效应及其校正方法

EH4电磁系统要求在“远区”观测。当发—收距较小时,测点在人工源的低频段处于过渡带中,数据发生畸变,从而形成过渡带低谷。提出一种线性校正方法,可对过渡带数据进行校正。     

四川盆地红层浅层风化带裂隙水及其合理开发利用

四川盆地红层地下水为基岩浅层裂隙水,赋存于红层丘陵区的宽谷风化带中。宽谷为红层地下水的含水单元。红层地下水富集部位在宽谷的排泄区,其地貌标志是宽谷下游较窄峡口的上部,该处有不同程度的沼泽化、盐渍化。红层风化带含水介质的形成经历了中、新生代水盆的沉积作用、成岩作用和表生地质作用等漫长复杂的物理化学过程。红层干旱地区的地下水开发应采用抽水和屯水相结合的方案。     

Asymmetrical valleys created by the geomorphic response of rivers to strike-slip fault

Offset fluvial valleys, including rivers beheaded and deflected by strike-slip faults, have long been used to estimate horizontal displacements on the faults. Larger rivers crossing such faults, however, sometimes show either no offset or only a small amount of offset compared to smaller rivers crossing the same faults. The larger rivers with higher erosional rates may widen their valleys asymmetrically downstream of strike-slip faults, rather than being beheaded or deflected. Examples are described from the Yellow River near the NE margin of the Tibetan Plateau. River beheading and asymmetrical widening are two end-members of a fluvial valley's response to strike-slip faulting, whereas deflection is a combination of both. Recognition of the formation of such asymmetrical valleys related to strike-slip faulting will help to understand fault activity better over longer time spans and enable a re-evaluation of many fault histories worldwide.