安徽淮北平原地下水超采评价与限采规划

以区域水文地质条件、开发利用现状、开采引发的主要问题及地下水脆弱性,对研究区进行限采规划分区。结合区内实际,将用水公平作为超采的衡量标准之一;将衡量标准与地下水流数值模拟方法或水位动态随机模拟方法相结合,评价超采程度现状;在其基础上,形成限采规划的技术方案。     

江汉平原东部构造格架及局部构造展布规律研究

充分利用钻井、测井、二维地震等资料,开展地质结构解剖,建立了江汉平原东部地层区域构造格架.工区受南北造山挤压,构造应力由造山带向盆内逐渐减弱,区内整体具有对冲干涉、南北分带、纵向叠置的结构特征.研究区内构造展布复杂而有序,主要表现为空间展布上的分带性及构造变形程度上的分区性:空间展布上可将该工区划分为北部秦岭-大别山推...     

Fatigue crack propagation model and size effect in concrete using dimensional analysis

It is well known that fatigue in concrete causes excessive deformations and cracking leading to structural failures. Due to quasi-brittle nature of concrete and formation of a fracture process zone, the rate of fatigue crack growth depends on a number of parameters, such as, the tensile strength, fracture toughness, loading ratio and most importantly the structural size. In this work, an analytical model is proposed for estimating the fatigue crack growth in concrete by using the concepts of dimensional analysis and including the above parameters. Knowing the governed and the governing parameters of the physical problem and by using the concepts of self-similarity, a relationship is obtained between different parameters involved. It is shown that the proposed fatigue law is able to capture the size effect in plain concrete and agrees well with different experimental results. Through a sensitivity analysis, it is shown that the structural size plays a dominant role followed by loading ratio and the initial crack length in fatigue crack propagation.     

三江北西段楚多曲矿床近东西向控矿断裂构造的识别及找矿意义(增刊)

三江北西段是西南三江成矿带的北段西延部分,已发现的矿床(点)明显受近东西向区域性断裂构造带及沿构造带分布的中酸性侵入岩体控制,成矿环境为典型的岩浆-构造活动环境。本文通过对楚多曲矿床在矿体特征、矿石特征、土壤地球化学特征对比基础上,新识别并确认了研究区近东西向断裂的控矿事实,改变了勘查工作只针对近南北向控矿断裂的现状;另外新发现了沿近南北向断裂与近东西向断裂复合部位侵入的二长斑岩体,针对其斑岩型矿化蚀变特征,初步探讨了斑岩型成矿可能;指出了研究区及区域下一步找矿方向。     

宁波市三江片区工业用地时空演变分析

宁波市三江片区正处于工业用地调整和"退二进三"的转型期,深入认识工业用地时空演变过程,把握工业用地调整的规律,是未来指导宁波工业用地调整的前提。本文利用1999-2009年宁波市土地利用现状图提取工业用地资料,借助GIS空间分析软件进行缓冲区分析、扇区分析和统计分析,得出工业用地时空演变的特征和规律以及未来布局的趋势。同时,结合宁波实际,分析了三江片区工业用地时空演变与主要交通方式之间的关系。本文定量化的分析方法为工业用地研究提供了方法论指导,研究结果对于宁波城市更新具有一定的参考价值。     

三江平原植被覆盖度对气候和土地利用变化的响应

为探讨三江平原植被覆盖度对气候变化和土地利用变化的响应特征,利用像元二分模型将2000~2014年逐月MODIS卫星遥感影像(NDVI)数据转换为相应的植被覆盖度数据,结合同期气象数据及2000、2005、2014年三期土地利用数据,借助ARCGIS工具,在土地利用未发生变化区域,采用偏相关分析和逐步回归分析方法,分析了气候变化对植被覆盖度的影响,并通过统计分析和矩阵运算,对不同土地利用类型转化方式下植被覆盖度的响应变化进行了量化。结果表明,三江平原植被长势整体较好,多年平均最大植被覆盖度为0.89;植被覆盖度与气温存在极显著的相关关系(P0.01),较降水而言,气温是影响植被覆盖度的主导因子,其中7月份的温度对植被覆盖度的影响最大;不同土地利用类型间存在明显的相互转化,导致相应区域植被覆盖度发生变化。     

豫东平原扶沟等地高氟地下水成因和富集条件探讨

针对研究区211眼机井地下水水质调查结果,分析研究区高氟水分布特征、演化规律、水化学特征、高氟水形成的主导条件、影响氟富集的主要因素。结果表明:该区域浅层地下水中F-质量浓度随地下水埋深的增加呈上升趋势;地下水化学类型以HCO3-Na·Mg和HCO3-Na型碱性水为主;主导氟富集的环境条件是强碱化水化学环境,地下水中F-质量浓度与Na+质量浓度呈正相关,F-质量浓度与Ca2+质量浓度和HCO-3质量浓度分别呈负相关关系;除自然因素外,人类频繁活动也影响着水体中氟化物质量浓度的变化。     

Classification and succession of former channels of the french upper rhone alluvial plain using mollusca

This paper deals with the results of an extensive sampling of eight former channels of the Rhǒne and eight of its tributary, the Ain River, France, designed to assess the value of molluscs as ?describers’? of ecosystem dynamics. The sampling was stratified on the distribution of aquatic macrophytes. The distribution of molluscs species is shown to provide information on the rate of eutrophication, the groundwater supply and the succession of the abandonned river channels toward semi-aquatic and terrestrial conditions. Molluscs, together with other macroinvertebrates, not only describe the present stage of these ecosystems but also provide some predictive information on their successional pattern for assistance in the management of the alluvial plain.     

涝渍胁迫对冬小麦拔节期碳通量的影响

为探究涝渍胁迫下农田生态系统碳平衡关系,在五道沟实验站设立典型试验区,以冬小麦拔节期为研究时段开展控制试验,设置涝、渍试验组和正常试验组,测量不同情景下冬小麦碳通量,并分析其变化趋势。研究结果表明:在正常情景下,拔节期冬小麦碳通量表现为碳汇,13时碳通量最低,晴天碳通量低于阴雨天,连续阴雨天后的初晴日碳通量大幅降低;涝渍情景可以降低拔节期冬小麦的碳通量,其中涝水情景的影响更为明显,第3d后涝渍情景对冬小麦碳通量影响明显减弱。碳通量随温度呈三次曲线变化,在正常和渍水情景下冬小麦碳通量在7℃左右达到最高点;在涝水情景下5℃左右达到最高点。拔节期碳的累积主要用于植株茎部生长,渍水3d为降低碳通量且不影响植株生长的最佳时点。研究成果可为维持农田生态系统碳平衡和建设生态灌区提供科学依据。     

Quantifying hydrologic alteration in an area lacking current reference conditions—The Mississippi alluvial plain of the south‐central United States

Quantifying hydrologic alteration in the Mississippi Alluvial Plain (MAP) of the south‐central United States is particularly difficult because of the lack of current reference, or even relatively undisturbed, streams and associated streamflow data. Impacts, such as water withdrawals for agriculture, weirs, dams, channelization, and other forms of regulation, within the MAP increased substantially beginning around 1960 suggesting that streamflow has since been altered. Using historical streamflow and climate data and explanatory variables, the U.S. Geological Survey developed random forest regression models to estimate expected reference monthly streamflows (pre‐1960) at 76 sites in the MAP and two adjacent Level III Ecoregions. To compensate for the lack of current reference stream sites in the study area, the pre‐1960 streamflow data were used as a surrogate to estimate current streamflow conditions without anthropogenic influence (inferring current reference conditions). Overall, nearly every site within the study area had less zero‐flow days than what historically has been observed and there were more low‐pulse spells. However, the frequency of floods remained relatively consistent.