Reconstructing the early 19th‐century Waal River by means of a 2D physics‐based numerical model

Suspended‐sediment concentration data are a missing link in reconstructions of the River Waal in the early 1800s. These reconstructions serve as a basis for assessing the long‐term effects of major interventions carried out between 1850 AD and the early 20th century. We used a 2D physics‐based morphodynamic model accounting for the influence of floodplain vegetation to fill in this gap. Historical discharge hydrographs were derived from a correlation between flow discharge records at Cologne and water level measurements of the Rhine branches in the Netherlands, taking into account the discharge distribution between the branches. Historical floodplain sedimentation rates were estimated using old cartographic information and recent geomorphologic field work. The computed historical sedimentation rates are found to be within the range of measured data, which suggests that fine suspended sediment concentrations in the early 1800s were comparable to contemporary ones. The computations show also how vegetation enhances the formation of natural levees close to the main channel and at the same time decreases the sedimentation rates in farther areas of the floodplain. A sensitivity analysis shows suspended sediment composition to have a strong influence on the resulting quantities and patterns of floodplain deposition. The reconstruction has also provided validation of the modelling tools to reproduce the effects of vegetation on sediment dynamics, enabling their implementation to study other cases. Copyright © 2010 John Wiley & Sons, Ltd.     

WACALIB version 3.3 — a computer program to reconstruct environmental variables from fossil assemblages by weighted averaging and to derive sample-specific errors of prediction

A computer program for reconstructing environmental variables (e.g. lake-water pH) from fossil assemblages (e.g. diatoms) by weighted averaging regression and calibration is described. The estimation of sample-specific errors of prediction by bootstrapping is outlined. The program runs on IBM-compatible personal computers.     

福建省政务信息资源标准规范改造与集成

对电子政务的标准化和网络化推行,政务信息数据标准化改造和共享集成是基础。本文分析了福建省政务信息资源的现状,提出了省级政务信息资源标准化、规范化改造的信息共享、分类体系、交换接口和信息服务模式。开发了福建省政务信息共享平台,充分应用XMLWebServices技术,将政务数据库分别按空间数据库、关系数据库、文件数据和多媒体数据4种类型,将分布在各单位、各行业的异构数据库集成到共享平台,并采用面向信息服务的集成架构,将多个分布式异构数据库进行实时的XML格式化,依据不同的共享级别按4种服务方式集成到各个应用系统中,实现数据库与应用系统的整合,提高政务信息资源的共享利用与服务水平。     

SCL与中国东部气候年代际变化

据宇地磁耦合原理,利用太阳黑子周期长度(SCL)的变化及其与地磁场(文中主要考虑地热)的关系,模拟计算并重建了中国东部历史时期的气温序列变化,除了个别时段外,模拟曲线与修正后的竺可桢曲线十分相似;分析了2500a来中国东部气候的年代际变化.结果表明,该曲线能较好地再现2500a来中国东部气候的冷暖变化.对竺氏曲线中有争议的几个冷暖时段,如公元150—350年的温暖期、1050—1150年的小气候适宜期等,模拟结果与后来研究者分析的结果相合.中唐至五代的气候冷暖交替变化不稳定.该曲线也能清晰地反映出小冰期中国东部气候各个时段的变化以及现代气候的变化趋势。     

广西岩溶石山区生态重建中土壤资源开发利用与保护对策

生态环境恶化、人民生活贫困是岩溶石山地区的普遍问题,也是西部大开发战略着重要解决的问题。广西是我国岩溶石山分布最广的省区之一,重建可持续发展的石山生态,是我区面临的紧迫而艰巨的任务,如何合理开发、利用和保护在独特岩溶环境条件下形成的宝贵的土壤资源,将是生态重建中的核心。      

Paleoclimate studies and natural-resource management in the Murray-Darling Basin II: unravelling human impacts and climate variability

The management of the water resources of the Murray-Darling Basin (MDB) has long been contested, and the effects of the recent Millennium drought and subsequent flooding events have generated acute contests over the appropriate allocation of water supplies to agricultural, domestic and environmental uses. This water-availability crisis has driven demand for improved knowledge of climate change trends, cycles of variability, the range of historical climates experienced by natural systems and the ecological health of the system relative to a past benchmark. A considerable volume of research on the past climates of southeastern Australia has been produced over recent decades, but much of this work has focused on longer geological time-scales, and is of low temporal resolution. Less evidence has been generated of recent climate change at the level of resolution that accesses the cycles of change relevant to management. Intra-decadal and near-annual resolution (high-resolution) records do exist and provide evidence of climate change and variability, and of human impact on systems, relevant to natural-resource management. There exist now many research groups using a range of proxy indicators of climate that will rapidly escalate our knowledge of management-relevant, climate change and variability. This review assembles available climate and catchment change research within, and in the vicinity of, the MDB and portrays the research activities that are responding to the knowledge need. It also discusses how paleoclimate scientists may better integrate their pursuits into the resource-management realm to enhance the utility of the science, the effectiveness of the management measures and the outcomes for the end users.     

Numerical analysis of the hydrofracturing behaviour of heterogeneous glutenite considering hydro‐mechanical coupling effects based on bonded particle models

The heterogeneity of tight reservoirs significantly influences hydrofracturing behaviours, such as crack morphology, type, initiation, propagation, and distribution. The accurate characterisation of the influencing mechanisms has become a pivotal issue in enhancing the fracturing stimulation of tight reservoirs, as well as in the prediction of tight oil and gas production. In this study, the hydrofracturing behaviours of heterogeneous glutenites and their influencing mechanisms were numerically investigated based on bonded particle models (BPMs). The geometry and mechanical properties of the natural glutenites were obtained using microfocus computed tomography (CT) and triaxial tests and were used to construct heterogeneous BPMs. The hydrofracturing behaviours of the heterogeneous BPMs under various in‐situ stresses were analysed with hydro‐mechanical coupling effects considered and compared with those of homogeneous BPMs under the same conditions. The numerical results show that gravels in heterogeneous glutenites inhibit crack propagation. The shear cracks that appear in the initial stage of crack development subsequently propagate and distribute around the injection hole, and there are fewer hydraulic shear cracks than tensile cracks. The crack morphologies of BPMs are found to be consistent with the experimental forms. The numerical simulation provides a way to understand the mechanisms that govern the hydrofracturing crack types and propagation of heterogeneous reservoirs.     

Holocene and Lateglacial relative sea‐level change in north‐west England: implications for glacial isostatic adjustment models

Relative sea‐level (RSL) change is reconstructed for central Cumbria, UK, based on litho‐ and biostratigraphical analysis from the Lateglacial to the late Holocene. The RSL curve is constrained using ten new radiocarbon‐dated sea‐level index points in addition to published data. The sea‐level curve identifies a clear Lateglacial sea‐level highstand approximately 2.3 m OD at c. 15–17 k cal a BP followed by rapid RSL fall to below ?5 m OD. RSL then rose rapidly during the early Holocene culminating in a mid‐Holocene highstand of approximately 1 m OD at c. 6 k cal a BP followed by gradual fall to the present level. These new data provide an important test for the RSL predictions from glacial isostatic adjustment models, particularly for the Lateglacial where there are very little data from the UK. The new RSL curve shows similar broad‐scale trends in RSL movement predicted by the models. However, the more recent models fail to predict the Lateglacial sea level highstand above present reconstructed by the new data presented here. Future updates to the models are needed to reduce this mismatch. This study highlights the importance for further RSL data to constrain Lateglacial sea level from sites in northern Britain. Copyright © 2012 John Wiley & Sons, Ltd.     

A reconstruction method for three‐dimensional pore space using multiple‐point geology statistic based on statistical pattern recognition and microstructure characterization

To predict the macroscopic properties (e.g., transport, electromagnetic, and mechanical properties) of porous media, it is necessary to have a three‐dimensional (3D) representation of porous media. We reconstruct the geologically realistic 3D structure of Fontainebleau sandstone based on the two‐dimensional (2D) thin sections by using the multiple‐point statistics method. For this method, the size of template is an important parameter that reflects the perceived scale of spatial structure of porous media. In this paper, we take advantage of entropy method to obtain the appropriate size of the template, which is proven to be correct and feasible. The reconstruction method proposed by us combines successive 2D MPS simulations as well as 3D MPS simulation, which takes account into the pore structure information (e.g., heterogeneity and connectivity) both intralayer and interlayer. This reconstruction method is tested on Fontainebleau sandstone for which 3D images from micro‐CT scanning are available. Applying local percolation theory analysis, this new approach can depict the expected patterns of geological heterogeneities. In addition, it also can well reproduce a high degree of connectivity of the pore space better than other reconstruction methods based on lower‐order statistics. Copyright © 2011 John Wiley & Sons, Ltd.