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Salinity intrusion characteristics analysis using EFDC model in the
downstream of Geum River 总被引:4,自引:0,他引:4
As social interest in the environmental conservation and ecological restoration has recently increased, more research works have
been done to resolve problems concerning environmental management of estuaries. In this study, a three-dimensional numerical model,
Environmental Fluid Dynamics Code (EFDC) was used in the analysis of the salinity intrusion characteristics in the downstream of
Geum River. The numerical simulation was performed to investigate the influence range for salinity intrusion when the gates were fully
opened. The conditions used for simulation were the four flow regimes in Geum River Basin, Korea. Results indicated that the ranges
of salinity intrusion from the barrage were 50.72 km (drought flow), 48.87 km (low flow), 46.56 km (normal flow) and 42.10 km (flood
flow). These results indicated that the EFDC model used for numerical simulation has high accuracy. The result concluded in this study
can be used as a basis in understanding the extent of salinity intrusion e ects at di erent flow rates. 相似文献
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基于解释结构模型的安全执行力分析 总被引:2,自引:0,他引:2
在对安全执行力的内涵界定的基础上,运用系统工程理论,对构成安全执行力的10个主要影响因素进行了定性和定量化处理,建立了安全执行力的6级多层递阶解释结构模型。通过分析安全执行力主要影响因素的关系结构,得到安全执行力的表层直接影响因素、中层间接影响因素和深层根本影响因素。企业的安全战略决策能力、政府安全立法和监管力度、社会对安全认知水平作为根本的影响因素,其影响是基础性的。结果表明,多层递阶解释结构模型从整体角度准确地揭示了安全执行力的主要影响因素的结构,对于深入把握安全执行力的形成、发展和演化机理有着重要的意义,是实现安全管理知识提取的有效途径。 相似文献
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目前一般采用振动台试验、离心振动台试验和有限元动力分析来获得土石坝在设计地震荷载作用下的形态和抗震性能。本文结合孔宪京等的土石坝振动台试验结果开展了颗粒流细观数值模拟研究,克服了传统连续介质力学的宏观连续性假设,形象而直观地表现出坝体在动力荷载作用下的破坏特征。数值模拟规律与振动台试验规律基本一致。同时还分析了坝体颗粒粘结强度和地震峰值加速度变化对坝体破坏特征的影响。数值结果表明,当颗粒间粘结强度较低时,表现为坝体表面颗粒的滑动破坏,粘结强度稍大时,会出现局部的小块颗粒团整体滑动破坏;随着峰值加速度的增大,坝顶沉降量在增大,坝体破坏特征不变。 相似文献
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Gabriel L. Brejão David J. Hoeinghaus María Angélica Pérez‐Mayorga Silvio F. B. Ferraz Lilian Casatti 《Conservation biology》2018,32(4):860-871
Deforestation is a primary driver of biodiversity change through habitat loss and fragmentation. Stream biodiversity may not respond to deforestation in a simple linear relationship. Rather, threshold responses to extent and timing of deforestation may occur. Identification of critical deforestation thresholds is needed for effective conservation and management. We tested for threshold responses of fish species and functional groups to degree of watershed and riparian zone deforestation and time since impact in 75 streams in the western Brazilian Amazon. We used remote sensing to assess deforestation from 1984 to 2011. Fish assemblages were sampled with seines and dip nets in a standardized manner. Fish species (n = 84) were classified into 20 functional groups based on ecomorphological traits associated with habitat use, feeding, and locomotion. Threshold responses were quantified using threshold indicator taxa analysis. Negative threshold responses to deforestation were common and consistently occurred at very low levels of deforestation (<20%) and soon after impact (<10 years). Sensitive species were functionally unique and associated with complex habitats and structures of allochthonous origin found in forested watersheds. Positive threshold responses of species were less common and generally occurred at >70% deforestation and >10 years after impact. Findings were similar at the community level for both taxonomic and functional analyses. Because most negative threshold responses occurred at low levels of deforestation and soon after impact, even minimal change is expected to negatively affect biodiversity. Delayed positive threshold responses to extreme deforestation by a few species do not offset the loss of sensitive taxa and likely contribute to biotic homogenization. 相似文献
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为研究应急管理系统的内部结构和协同效果,基于ISM二维云模型展开应急管理协同度研究。运用结构解释模型(ISM)剖析应急管理复杂系统内部的层次关系,依据影响因素递阶层次图构建应急管理协同度评价指标体系;提出1种递阶中心度权重法用于求解各指标的权重系数,用中心度与层级系数反映各指标的重要性与结构性;将二维云模型引入到应急管理协同度研究,处理各指标预防阶段和响应阶段的模糊性与随机性问题;应用上述方法对京津冀应急管理协同度进行探索性研究,结果表明:京津冀应急管理综合协同度等级为良,3地各部门之间的横向信息沟通有待加强,需提高应急预案在响应阶段的可行性,同时加大预防阶段的科技支撑能力,研究方法和结论可为以京津冀为代表的城市群的应急管理协同水平的持续提高提供参考和借鉴。 相似文献
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