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471.
黄河三角洲地区地下淡水(微咸水)的形成与演化   总被引:10,自引:0,他引:10  
黄河三角洲地区地下淡水(微咸水)资源贫乏,咸水广布。南部冲洪积平原受第二次海侵层位的影响形成大面积咸水,后被逐渐淡化。近年来由于开采量加大,又使北部咸水南侵。海积冲积平原随着黄河河道的变迁,仅在黄河现行河道两侧和充水的黄河故道带分布有淡水(微咸水)。近代,现代黄河三角洲古河道带和决口扇淡水体已被咸化。  相似文献   
472.
The Campos, Santos and Pelotas basins have been investigated in terms of 2D seismo-stratigraphy and subsidence. The processes controlling accommodation space (e.g. eustacy, subsidence, sediment input) and the evolution of the three basins are discussed. Depositional seismic sequences in the syn-rift Barremian to the drift Holocene basin fill have been identified. In addition, the subsidence/uplift history has been numerically modeled including (i) sediment flux, (ii) sedimentary basin framework, (iii) relation to plate-tectonic reconfigurations, and (iv) mechanism of crustal extension. Although the initial rift development of the three basins is very similar, basin architecture, sedimentary infill and distribution differ considerably during the syn-rift sag to the drift basin stages. After widespread late Aptian–early Albian salt and carbonate deposition, shelf retrogradation dominated in the Campos Basin, whereas shelf progradation occurred in the Santos Basin. In the Tertiary, these basin fill styles were reversed: since the Paleogene, shelf progradation in the Campos Basin contrasts with overall retrogradation in the Santos Basin. In contrast, long-term Cretaceous–Paleogene shelf retrogradation and intense Neogene progradation characterize the Pelotas Basin. Its specific basin fill and architecture mainly resulted from the absence of salt deposition and deformation. These temporally and spatially varying successions were controlled by specific long-term subsidence/uplift trends. Onshore and offshore tectonism in the Campos and Santos basins affected the sediment flux history, distribution of the main depocenters and occurrence of hydrocarbon stratigraphic–structural traps. This is highlighted by the exhumation and erosion of the Serra do Mar, Serra da Mantiqueira and Ponta Grossa Arch in the hinterland, as well as salt tectonics in the offshore domain. The Pelotas Basin was less affected by changes in structural regimes until the Eocene, when the Andean orogeny caused uplift of the source areas. Flexural loading largely controlled its development and potential hydrocarbon traps are mainly stratigraphic.  相似文献   
473.
Stakeholder consultation is being adopted as standard practice in the planning and management of natural resource management programs. While the utility of stakeholder participation has been investigated for the evaluation and implementation phases of natural resource management programs, few studies have examined the utility of stakeholder consultation during the initial phases of developing such programs. This paper presents a case study from a project developing a marine and coastal monitoring program for the Pilbara and Kimberley region of northern Western Australia. Via a series of workshops held in the region, stakeholders were asked to prioritise future research needs using several voting procedures. During the analyses of the results from the different voting procedures, it became apparent that there were high levels of inconsistency, poor correlation, and contradiction, between participants’ responses. Despite the rigour of the selection process used to identify ‘suitable’ stakeholders for the workshops, these results show that stakeholders did not have the technical or broader contextual knowledge about marine ecosystems to effectively and objectively contribute to the research prioritisation and planning process. Based on the outcomes of this study, we argue that project designers need to be clear about why they are involving stakeholders in a project, particularly in light of the costs involved (financial, time, resources, costs to the stakeholder) in stakeholder consultation. Stakeholder involvement may be appropriate in later stages of developing natural resource management programs (implementation and management), however, stakeholder involvement is not appropriate in the initial phases of such programs, where scientific expertise is essential in formulating scientific concepts and frameworks.  相似文献   
474.
The assessment of sustainable development is a relatively recent advent in policy and the evaluation of industry structural adjustments. Although the elements of economic and environmental assessment have been relatively well developed and accepted, the effective inclusion of ‘social’ aspects in assessments of sustainable development are still being grappled with.  相似文献   
475.
Tsunamis can leave deposits on the land surface they inundate. The characteristics of tsunami deposits can be used to calculate tsunami run-up height and velocity. This paper presents a reconstruction of tsunami run-up from tsunami deposit characteristics in a simple mathematical model. The model is modified and applied to reconstruct tsunami run-ups at Ao Kheuy beach and Khuk Khak beach, Phangnga province, Thailand. The input parameters are grain-size and maximum run-up distance of the sediment. The reconstructed run-up heights are 4.16–4.91 m at Ao Kheuy beach and 5.43–9.46 m at Khuk Khak beach. The estimated run-up velocities (maximum velocity) at the still water level are 12.78–19.21 m/s. In the area located 70–140 m inland to the end of run-up inundation, estimated mean run-up velocities decrease from approximately 1.93 m/s to 0 m/s. Reasonably good agreements are found between reconstructed and observed run-up heights. The tsunami run-up height and velocity can be used for risk assessment and coastal development programs in the tsunami affected area. The results show that the area from 0 to 140 m inland was flooded by high velocity run-ups and those run-up energies were dissipated mainly in this area. The area should be designated as either an area where settlement is not permitted or an area where effective protection is provided, for example with flood barriers or forest.  相似文献   
476.
中国沿海地区高质量发展的路径   总被引:2,自引:1,他引:1  
孙久文  蒋治 《地理学报》2021,76(2):277-294
高质量发展是跨越中等收入陷阱、跻身发达经济体的关键举措.随着改革开放的深入,沿海地区正日益成为经济增长的压舱石、国家制造业中心、打造创新型国家的前沿地带、开放型经济建设的排头兵、绿色发展的示范窗口,具备高质量发展的典型特征,将有效带动内陆地区步入高质量发展的正轨,形成对整个国家高质量发展的有力支撑,塑造区域协调发展新格...  相似文献   
477.
为提高饶河流域洪水预报精度,将全过程联合校正(EPJC)方法与三水源新安江(XAJ)模型结合,按一定比例划分洪水预报总误差为各过程误差,基于系统响应理论反演得到面雨量计算误差和模型参数误差,重新输入流域水文模型正演得出校正后的洪水过程.选取洪峰流量相对误差、峰现时间绝对误差、径流深相对误差和确定性系数作为模型评价指标,...  相似文献   
478.
地震研究新方法——洋壳流理论简介   总被引:1,自引:0,他引:1  
根据交换平衡力学原理[1],简要地介绍了洋壳流的概念及其运动特点。根据运行区域和方向的不同,把三大洋的海底扩张运动划分为不同的洋壳流,并绘出运行路线图。提出洋壳流运动方向、路线及力作用大小的判断方法,通过不同区域洋壳流相互力作用的对比,分析海底扩张运动对地震时空分布及变化规律的影响。  相似文献   
479.
广西大厂锡多金属矿床研究进展   总被引:3,自引:0,他引:3  
大厂锡多金属矿床是世界闻名的超大型矿床,笔者从构造控矿、同位素测年、流体包裹体、成矿物质来源及同生沉积成矿等五个方面综述了近半个世纪来该矿床的一些研究进展,并结合近年来野外调查研究,认为大厂锡多金属矿床属后生成因,成岩、成矿是燕山晚期同一构造-热事件的产物,成矿过程中有幔源流体的显著参与,矿体产出形态的空间变化受不同深度的构造特征所控制。  相似文献   
480.
孙平军  罗宁  刘菊  彭雅丽 《热带地理》2022,42(11):1816-1828
源于时代之变而构筑的双循环新发展格局是市场经济条件下多尺度空间输出理论与劳动地域大分工的“叠加”,为新型城镇化发展带来新的动力源泉。为了揭示这种影响,首先将科技创新和制度改革这2个城镇化发展动力外生变量内生化,构建基于“四维驱动力模型+创新力+制度力”的城镇化动力因子分析框架,结合主成分回归模型对2000年以来重庆市城镇化发展动力进行分析,并据此引入波特的“钻石模型”对其城镇化发展路径进行系统思考。结果表明:1)纳入动力因子体系的创新力和制度力对重庆市城镇化发展产生显著的正向驱动效应,其中创新力表现最为明显。2)重庆市城镇化发展是“六维力”共同作用的结果,但市场力和行政力依然是最主要的驱动力;其次是创新力、内源力和外向力,其中创新力对城镇化发展的驱动效应已在阶段2(2010—2018年)超越行政力的作用效应;最后是制度力;间接反映重庆市城镇化本身是一个内生作用的过程,构筑“以国内大循环为主体、国内国际双循环相互促进”新发展格局具有客观必然性和前瞻性。3)基于波特“钻石模型”分析指出:重庆市存在增长极体量小、市场购买力不足、产品低端化、同质化现象严重等问题,并据此从发展高级生产要素、创造...  相似文献   
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