The role of technical measures in European fisheries management and how to make them work better     

Suuronen  Petri; Sarda  Francesc 《ICES Journal of Marine Science》2007,64(4):751-756

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Analysis of channel transmission losses in a dryland river reach in north‐eastern Brazil using streamflow series,groundwater level series and multi‐temporal satellite data     

Alexandre Cunha Costa  Saskia Foerster  José Carlos de Araújo  Axel Bronstert 《水文研究》2013,27(7):1046-1060

Scarcity of hydrological data, especially streamflow discharge and groundwater level series, restricts the understanding of channel transmission losses (TL) in drylands. Furthermore, the lack of information on spatial river dynamics encompasses high uncertainty on TL analysis in large rivers. The objective of this study was to combine the information from streamflow and groundwater level series with multi‐temporal satellite data to derive a hydrological concept of TL for a reach of the Middle Jaguaribe River (MJR) in semi‐arid north‐eastern Brazil. Based on this analysis, we proposed strategies for its modelling and simulation. TL take place in an alluvium, where river and groundwater can be considered to be hydraulically connected. Most losses certainly infiltrated only through streambed and levees and not through the flood plains, as could be shown by satellite image analysis. TL events whose input river flows were smaller than a threshold did not reach the outlet of the MJR. TL events whose input flows were higher than this threshold reached the outlet losing on average 30% of their input. During the dry seasons (DS) and at the beginning of rainy seasons (DS/BRS), no river flow is expected for pre‐events, and events have vertical infiltration into the alluvium. At the middle and the end of the rainy seasons (MRS/ERS), river flow sustained by base flow occurs before/after events, and lateral infiltration into the alluvium plays a major role. Thus, the MJR shifts from being a losing river at DS/BRS to become a losing/gaining (mostly losing) river at MRS/ERS. A model of this system has to include the coupling of river and groundwater flow processes linked by a leakage approach. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Quantifying the impact of no-till on runoff in southern Brazil at hillslope and catchment scales     

Ana L. Londero  Jean P. G. Minella  Fabio J. A. Schneider  Dinis Deuschle  Danrlei Menezes  Olivier Evrard  Madalena Boeni  Gustavo H. Merten 《水文研究》2021,35(3):e14094

No-till (NT) is a conservation system that improves the hydrological regime of agricultural slopes by providing greater surface protection and benefits to the physical and hydrological properties of soils. However, the isolated use of NT is not enough to control runoff and its associated degradation processes. Therefore, this study aimed to evaluate the runoff of agricultural slopes under NT under different runoff control conditions by monitoring 63 rainfall events in two 2.4-ha zero-order catchments and 27 rainfall events in four 0.6-ha macroplots. The catchments are paired and similar in terms of the type of soil and relief, but different regarding the presence of terraces. The macroplots have different soil and crop management systems. By using monitoring techniques, the hyetographs and hydrographs revealed the influence of the different types of management on the catchments and macroplots and allowed rainfall characteristics, runoff volume, runoff coefficients, water infiltration, peak runoff, response times, and curve number to be analysed. The terraces positively affected the NT and controlled runoff and related variables, in addition to infiltration significantly increasing and runoff reducing in the terraced catchment. All the hydrological information assessed pointed to the positive effects provided by the presence of the terraces. The results in the macroplots showed that high amounts of phytomass and/or chiselling do not control runoff and its correlated variables in medium and high magnitude events. The study concludes by underlining the need for additional measures to control runoff (terraces), even in areas under NT and with high phytomass production. Additionally, the study emphasizes the importance of monitoring at the catchment scale to better understand the hydrological behaviour of agricultural areas and provide the necessary parameters to effectively control runoff.  相似文献   

基于路基土蠕变效应的路基预应力损失模型研究     

冷伍明  邓志龙  徐方  张期树  董俊利  刘思慧 《岩土力学》2022,43(6):1671-1682

新型预应力路基技术可用于整治路基病害或强化既有线路基,研究其预应力损失规律对保障预应力路基工程的长期安全具有重要意义。基于弹性理论提出了预应力路基侧压力板与路基边坡接触面中心点后方水平路径上附加应力的计算方法,分析表明该特征路径上水平附加应力随距板−土接触面中心点距离的增加呈现良好的指数函数衰减关系。基于水平附加应力的指数函数扩散规律及路基土的蠕变行为,推导了路基土的蠕变变形计算公式。进一步基于蠕变变形与预应力钢筋回缩变形的协调性,建立了路基预应力的损失模型和计算方法,并结合FLAC3D数值仿真开展了对比分析。研究表明：钢筋预拉力损失的理论预测曲线与数值仿真曲线吻合良好,二者偏差不足5%,论证了路基预应力损失模型的有效性;钢筋预拉力可在锚固后的60 d内达到稳定,且预拉力的稳定值可达其初始值的85%～90%,说明新型预应力路基技术可为路基土提供相当可观的稳定附加围压,从而通过改善路基土的应力状态达到强化路基的目的。  相似文献   

偏心跟管钻进技术在公路高边坡加固工程中的应用          下载免费PDF全文

马元宏  柯玉军 《探矿工程》2010,37(2):67-68

介绍了偏心跟管钻进技术在西安一安康高速公路某高边坡破碎地层中的成孔工艺、施工配套设施和相应的技术措施。  相似文献   

工程桩静载试验确定PHC管桩承载力     

潘志军 《福建地质》2010,29(1):39-41

以工程实例介绍静压管桩基础的设计承载力取值,采用先施工工程桩进行静载试验,以其结果反算单桩竖向承载力,结合桩的入土长度等给出应用于工程实际的单桩竖向承载力设计值(R)的方法,供同行借鉴。  相似文献   

冕宁县地震经济损失预测及社会经济影响分析     

张家涛  孙林松  蒋能强  秦启沛  杨建生 《高原地震》1993,(2)

本文根据冕宁县的社会经济调查资料和建筑物群体震害预测结果,对未来地震引起的经济损失进行了预测,并对地震后可能引起的社会经济影响作了初步分析。  相似文献   

建立生命的地震易损性概率矩阵初探     

傅征祥 《中国地震》1993,9(3):205-210

1966年3月8日河北省邢台地震(M_S=6.8)震害调查资料的统计分析结果表明,地震造成人员伤亡的损失程度遵从正态的概率分布,据此初步建立起土坯墙房的生命地震易损性概率矩阵P(D_0|I)。该矩阵将可应用在地震灾害生命损失的概率预测研究中。  相似文献   

Changes in diffuse phosphorus and nitrogen inputs into surface waters in the Rhine watershed in Switzerland     

Volker Prasuhn  Ulrich Sieber 《Aquatic Sciences - Research Across Boundaries》2005,67(3):363-371

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确定全国地震重点监视防御区的研究   总被引：2，自引：6，他引：2  

张国民  傅征祥  王晓青  刘桂萍 《中国地震》2006,22(3):209-221

首先阐述确定地震重点监视防御区的分级原则（分为国家级和省级），突出重点原则（重点监视防御区面积占全国或省辖面积的较小部分，而其地震损失占总和的大部分）和科学技术思路（以地震危险性预测为基础，以灾害损失的预测为依据确定地震重点监视防御区）。其次，回顾了确定1996～2005年全国地震重点监视防御区的研究成果。回顾表明，在1996～2005年间，发生在我国大陆有监测能力地区的10次强震中，有8次发生在防御区内及其邻近地区，其经济和生命损失已分别占大陆的67％和92％。最后，简要介绍为确定2006-2020年全国地震重点监视防御区而开展的研究工作，包括基于地震学、地震地质学、大地测量学、地震工程学、社会学和预测学而进行的10年尺度的中长期地震危险预测研究，以及所得到的2006-2020年全国地震危险概率预测图、地震危险性（烈度）预测图、地震灾害损失预测图和地震危险性综合指数预测图等。  相似文献