Rivers, chemical weathering and Earth's climate

We detail the results of recent studies describing and quantifying the large-scale chemical weathering of the main types of continental silicate rocks: granites and basalts. These studies aim at establishing chemical weathering laws for these two lithologies, describing the dependence of chemical weathering on environmental parameters, such as climate and mechanical erosion. As shown within this contribution, such mathematical laws are of primary importance for numerical models calculating the evolution of the partial pressure of atmospheric CO₂ and the Earth climate at geological timescales. The major results can be summarized as follow: (1) weathering of continental basaltic lithologies accounts for about 30% of the total consumption of atmospheric CO₂ through weathering of continental silicate rocks. This is related to their high weatherability (about eight times greater than the granite weatherability); (2) a simple weathering law has been established for basaltic lithologies, giving the consumption of atmospheric CO₂ as a function of regional continental runoff, and mean annual regional temperature; (3) no such simple weathering law can be proposed for granitic lithologies, since the effect of temperature can only be identified for regions displaying high continental runoff; (4) a general law relating mechanical erosion and chemical weathering has been validated on small and large catchments. The consequences of these major advances on the climatic evolution of the Earth are discussed. Particularly, the impacts of the onset of the Deccan trapps and the Himalayan orogeny on the global carbon cycle are reinvestigated. To cite this article: B. Dupré et al., C. R. Geoscience 335 (2003).     

三峡工程大江截流的水文技术

鉴于三峡工程大江截流水深大，流量大，工期紧，特别是截流过程中要考虑不断航因素，因此，在大江截流和二期围堰阶段的施工进程中，应充分考虑到各方面的因素，尽可能采取一切减少大江截流和二期围堰施工难度的手段和措施，其中水文测验，水文气象预报，河道观测，水文分析与计算和水力学计算等水文工作则是为顺利实施高质量大江截流的重要条件。     

天山北坡降水对河流水沙情势影响

以天山北坡头屯河流域为例，在对山区不同海拔的降水特征、侵蚀产沙情势以及河流水沙运移特点分析的基础上，详尽就山区降水对河流水沙情势的年际变化、年内变化以及月变化的影响进行了分析研究，并就降水对不同海拔的河流水沙情势的影响强度及相互关系作了探讨．     

赣东北地区前震旦系地层金的原生富集趋势探讨

在分析变质岩的含金性及地球化学性质的基础上，认为与金成矿有关的主要元素均源自前震旦系。指出了金的原生富集趋势和存在的矿源层。为在该区寻找金矿指出了方向     

Effects of geology and human activity on the dynamics of salt-water intrusion in three coastal aquifers in southern Spain

 Mathematical modelling of salt-water intrusion processes in three aquifers on the southern coast of Spain (Río Verde, Río Vélez and Castell de Ferro) reveals that, although all three systems are subject to the same climate and seasonal over-exploitation, geological and human factors have very different effects on the dynamics of contamination. In the Río Verde aquifer, the most important influence is the high volume of extractions occurring during the dry season; in Río Vélez, the intrusion is strongly controlled by infiltration of water from the river to the aquifer, and, in the Castell de Ferro system, an intensely karstified carbonate massif lying in contact with both the sea water and the detrital aquifer represents the main entrance point for influx of sea water and subsequent washing of the aquifer. We have undertaken a mathematical simulation of various possible measures to counteract intrusion, according to the specific characteristics of the process in each aquifer. These measures include artificial recharge, use of natural recharge from the river as a hydraulic barrier, and the construction of a low-permeability barrier. Received: 5 December 1995 · Accepted: 12 April 1996     

大汶河流域洪灾的成因及防治对策

阐述了大汶河流域洪涝灾害的特点,并对洪涝灾害发生的原因进行了分析,提出了预防为主、综合治理、系统防治和重点防治相结合、标本兼治的防治思路及具体防治对策.     

Sedimentary environment and development controls of the hydrocarbon source beds:Middle and Upper Proterozoic in northern North China

Problem on development control of marine source bed hold in Chinese petroleum industry progression. The Hongshuizhuang Formation,Tieling Formation and Xiamaling Formation in the Middle and Upper Proterozoic are important hydrocarbon source beds in northern North China, and investigation of their sedimentary environments and the controls has great significance for petroleum exploration in North China. Based on sedimentology (sequence stratigraphy), palaeoecology, sedimentary geochemistry, and sedimentary palaeogeography, their development pattern is discussed. All these studies indicate that the development controls of the hydrocarbon source beds include a favorite palaeogeographic location, exceeding propagation of biomes in low and middle latitudes, anoxic environments, enrichment of phosphorus element and the adsorption of clay minerals during the preservation of organic matter in the marine carbonates.     

2003年淮河流域大水期间体积降水量的研究

针对 2 0 0 3年梅雨期淮河流域大水提出了体积降水量的概念及其计算方法 ,在计算出淮河流域和其各子流域逐日和总体积降水量的基础上 ,将体积降水量与水文站的水位和流量进行了对比分析。结果表明 :水位对累计体积降水量有较好的即时响应 ,流量对体积降水量有较好的延迟响应。另外 ,讨论了流域体积降水量的预报问题 ,用国内外数值天气预报产品和中央气象台指导预报产品 ,进行了流域体积降水量预报试验 ,并对预报结果进行了检验分析。结果表明 :在目前天气预报水平条件下 ,利用数值天气预报和中央气象台业务预报产品制作体积降水量是可行的 ,能够延长洪水预报的预见期 ;而且 ,数值天气预报产品在预报体积降水量方面有明显的优势 ,因此可以直接利用数值天气预报产品进行体积降水量的客观预报 ,为防汛工作提供重要的依据。     

柯坪河流域地下水资源的有效利用方式探讨

柯坪河流域分布于新疆境内，包括苏巴什盆地、柯坪盆地和阿恰山前地区．柯坪河是柯坪县最大的河流，上游名为苏巴什河，下游与红沙河汇合后称阿恰河．盆地与山前平原由柯坪河串起，水资源沿途不断汇入，并在不同河段有反复出露入渗．流域内无高山冰川，中山区降水是水资源的唯一来源．流域内水质普遍较差，溶解性总固体含量由北西向南东逐渐增高，当地居民生活饮用水供水水质不能满足生活饮用水标准．根据当地的地下水水资源特点，采取合适的管理利用方式，可使得较低溶解性总固体含量地下水资源能够更有效的被利用．     

曲线铁路路基下沉病害检测与分析

以阐明曲线铁路路基下沉病害检测、基床强度评估和病害成因分析方法为目标，采用轻便动力触探试验和土工试验方法对沪宁线下行k55 450-k55 500曲线路基下沉病害段进行了试验测试，根据轻便动力触探和土工试验结果，计算出曲线路基基床承载力，与曲线线路路基中总应力进行比较，评估了基床强度状况，分析出该段曲线铁路路基病害产生的成因。