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31.
Gabriele Villarini James A. Smith Mary Lynn Baeck Witold F. Krajewski 《Journal of the American Water Resources Association》2011,47(3):447-463
Villarini, Gabriele, James A. Smith, Mary Lynn Baeck, and Witold F. Krajewski, 2011. Examining Flood Frequency Distributions in the Midwest U.S. Journal of the American Water Resources Association (JAWRA) 47(3):447‐463. DOI: 10.1111/j.1752‐1688.2011.00540.x Abstract: Annual maximum peak discharge time series from 196 stream gage stations with a record of at least 75 years from the Midwest United States is examined to study flood peak distributions from a regional point of view. The focus of this study is to evaluate: (1) “mixtures” of flood peak distributions, (2) upper tail and scaling properties of the flood peak distributions, and (3) presence of temporal nonstationarities in the flood peak records. Warm season convective systems are responsible for some of the largest floods in the area, in particular in Nebraska, Kansas, and Iowa. Spring events associated with snowmelt and rain‐on‐snow are common in the northern part of the study domain. Nonparametric tests are used to investigate the presence of abrupt and slowly varying changes. Change‐points rather than monotonic trends are responsible for most violations of the stationarity assumption. The abrupt changes in flood peaks can be associated with anthropogenic changes, such as changes in land use/land cover, agricultural practice, and construction of dams. The trend analyses do not suggest an increase in the flood peak distribution due to anthropogenic climate change. Examination of the upper tail and scaling properties of the flood peak distributions are examined by means of the location, scale, and shape parameters of the Generalized Extreme Value distribution. 相似文献
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含聚合物污水回注时污染地层的主要物质分析 总被引:5,自引:0,他引:5
笔者系统分析了大庆油田南三区东部聚合物驱产出水处理前后原油、聚合物、固体悬浮物、无机离子和细菌等成分的含量及其固体悬浮物颗粒直径大小与分布,并且对该区聚合物驱产出水主要特征进行了总结,在此基础上,根据油层损害机理并且结合该区油层的孔渗特征,研究和确定了污染物质。得出结论:聚合物驱产出水中硫酸盐还原菌是主要污染物质,此外,向萨葡油层的低、中渗层及高台子油层回注时,固体悬浮物和原油也是主要污染物质,而聚合物仅对低渗层造成损害;常规处理方法对污水中原油处理效果最好,而对PAM和固体悬浮物处理不太理想。 相似文献
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Jeffrey J. Opperman Ryan Luster Bruce A. McKenney Michael Roberts Amanda Wrona Meadows 《Journal of the American Water Resources Association》2010,46(2):211-226
Opperman, Jeffrey J., Ryan Luster, Bruce A. McKenney, Michael Roberts, and Amanda Wrona Meadows, 2010. Ecologically Functional Floodplains: Connectivity, Flow Regime, and Scale. Journal of the American Water Resources Association (JAWRA) 46(2):211-226. DOI: 10.1111/j.1752-1688.2010.00426.x Abstract: This paper proposes a conceptual model that captures key attributes of ecologically functional floodplains, encompassing three basic elements: (1) hydrologic connectivity between the river and the floodplain, (2) a variable hydrograph that reflects seasonal precipitation patterns and retains a range of both high and low flow events, and (3) sufficient spatial scale to encompass dynamic processes and for floodplain benefits to accrue to a meaningful level. Although floodplains support high levels of biodiversity and some of the most productive ecosystems on Earth, they are also among the most converted and threatened ecosystems and therefore have recently become the focus of conservation and restoration programs across the United States and globally. These efforts seek to conserve or restore complex, highly variable ecosystems and often must simultaneously address both land and water management. Thus, such efforts must overcome considerable scientific, technical, and socioeconomic challenges. In addition to proposing a scientific conceptual model, this paper also includes three case studies that illustrate methods for addressing these technical and socioeconomic challenges within projects that seek to promote ecologically functional floodplains through river-floodplain reconnection and/or restoration of key components of hydrological variability. 相似文献
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On 30 May 2008, the Government of the Netherlands informed the national parliament about the effectiveness of preventive evacuation of coastal and river areas in case of flooding. Analysis of a case study showed that it is impossible to evacuate coastal areas preventively within a 48-hour time span preceding a worst credible scenario flood caused by a storm surge. This fact illustrates the need for alternative evacuation strategies, such as vertical evacuation (evacuating to safe havens, inside the flood zone) or shelter-in-place (hiding), to reduce loss of life and the impact of the evacuation. This paper defines these strategies and demonstrates, by returning to the case study used by the Dutch government, that they require different measures, methods of approach, and crisis management processes. In addition, it addresses the need for flexible and scalable preparation so that after detecting and understanding the threat, authorities and citizens can make decisions about different evacuation strategies. 相似文献
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Method for Rapidly Assessing the Overtopping Risk of Bridges Due to Flooding over a Large Geographic Region 下载免费PDF全文
Yawen Shen Jonathan L. Goodall Steven B. Chase 《Journal of the American Water Resources Association》2017,53(6):1437-1452
Hydraulic events are a leading cause of bridge failures. While these hydraulic events are accounted for in bridge design, changing environmental and land use conditions require continual updating of this risk. For example, after a bridge has been constructed, streamflow can change in unanticipated ways as a result of land use changes, geomorphic changes, and climate change. The objective of this research was to create a screening method able to quickly and inexpensively estimate overtopping risk across a collection of bridges based on the current streamflow conditions. The method uses a geographic information system, nationally available and standardized datasets, and recent regression equations to quantify bridge vulnerability to overtopping for flooding with varying return periods. This screening method could also be used to assist decision makers in updating the Waterway Adequacy field in the National Bridge Inventory, which indicates the overtopping risk of bridges. The method was applied to a portion of the Hampton Roads region of Virginia, United States that includes 475 bridges. The results of the analysis, when combined with transportation data for bridges, aid decision makers to assign further resources to complete more detailed analyses of bridges identified as being at risk for overtopping. 相似文献
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以丙烯酰胺(AM)和烷基酚聚醚(APAP)为单体,采用反相乳液聚合法制备了流动性好的非离子型聚丙烯酰胺絮凝剂(PAM-APAP)。考察了乳化剂和引发剂的种类、单体总质量分数、单体配比和反应温度等因素对聚合反应的影响。实验结果表明,制备PAM-APAP的最佳工艺条件为:单体总质量分数35%、m(AM)∶m(APAP)=9.0∶1.0、Span80+Tween80复配乳化剂加入量为油水总质量的7%、m(Span80)∶m(Tween80)=7.0∶1.5、V50加入量为单体总质量的1.5‰、反应温度50℃。PAM-APAP具有较好的絮凝效果,与其他絮凝剂相比用量较少,在加入量为100mg/L时,对聚合物驱油中产生的含聚合物污水的浊度去除率为87.9%,去油率为89.5%,且絮体不黏壁。 相似文献