A comparison of the effectiveness of the roots of two grass species in reducing soil erosion on alluvial fans in south-east China     

Fangshi Jiang  Kaiwen He  Jiahui Lin  Hui Li  Zhenzhi Zhan  Jinshi Lin  Hongli Ge  Ming Kuang Wang  Yanhe Huang 《水文研究》2020,34(1):96-110

The effects of root systems on soil detachment by overland flow are closely related to vegetation types. The objective of this study was to quantify the effects of two gramineous roots (Paspalum mandiocanum with shallow roots and Pennisetum giganteum with deep roots) on soil detachment capacity, rill erodibility, and critical shear stress on alluvial fans of benggang in south-east China. A 4-m-long and 0.12-m-wide flume was used. Slope steepness ranged from 9% to 27%, and unit flow discharge ranged from 1.39 × 10⁻³ to 4.19 × 10⁻³ m² s⁻¹. The mean detachment capacities of P. mandiocanum and P. giganteum lands were 18% and 38% lower than that of bare land, respectively, and the effects of root on reducing soil detachment were mainly reflected in the 0- to 5-cm soil layer. The most important factors in characterizing soil detachment capacity were root length density and soil cohesion, and soil detachment capacity of the two grass lands could be estimated using flow shear stress, soil cohesion, and root length density (NSE = 0.90). With the increase in soil depth, rill erodibility increased, whereas shear stress decreased. The mean rill erodibilities of P. mandiocanum and P. giganteum lands were 81% and 61% as much as that of bare land, respectively. Additionally, rill erodibilities of the two grass lands could be estimated as an exponential function by root length density and soil cohesion (NSE = 0.88). The mean critical shear stress of P. mandiocanum and P. giganteum lands was 1.29 and 1.39 times that of bare land, respectively, and it could be estimated with a linear function by root length density (NSE = 0.76). This study demonstrated that planting of the two grasses P. mandiocanum and P. giganteum could effectively reduce soil detachment and enhance soil resistance to erosion on alluvial fans, with the deep roots of P. giganteum being more effective than the shallow roots of P. mandiocanum. The results are helpful for understanding the influencing mechanism of root systems on soil detachment process.  相似文献   

激光跟踪仪在核电站主管道安装中的应用     

郭建兵 《北京测绘》2020,(1):123-125

目前,核电站的主管道焊接越来越多的采用了自动焊技术,这有利于提高焊接质量效率,还可以压缩建设成本。然而,主管道自动焊对焊缝的限差较现有工艺要求更高,高精度的测量是实现主管道自动焊的必要条件之一。本文针对主管道自动焊管口组队高精度的技术要求,提出采用激光跟踪仪对主管道自动焊相关的设备进行更为精密的三维工业测量,通过理论技术评定测量精度,然后选择测量仪器和编制具体的测量方案,最终保证了主管道自动焊精确组对的实现。  相似文献   

内蒙古突泉盆地南部中侏罗世植物群初探     

张德军  张健  郑月娟  陈树旺  苏飞  黄欣  张海华 《地质与资源》2019,28(1):7-12

报道了突泉盆地南部牤牛海地区发现的植物大化石15属26种，主要包括有节类Noecalamites sp.、Equisetites sp.，真蕨类Todites goeppertianus、T.williamsoni、Cladophlebis argutula、C.hsiehiana、C.shansiensis，松柏类Pityospermum staratschini、P.nordenskioldi、Podozamites schenki、P.lanceolotus，银杏类Czekanowskia rigida、Ginkgo huttoni、Ginkgoites cf.Sibiricus、G.sibiricus、G.cf.marginatus、G.lepidus、Vittifoliolum paucinerve、Phoenicopsis speciosa、Sphenobailra sp.，苏铁类Nilssonia sinensis以及裸子植物花果和种子Carpolithus sp.等，其中以真蕨类（26.9%）和银杏类（38.5%）占优势，松柏类（19.2%）占一定比重，含少量的木贼类（7.7%）、苏铁类（3.8%）以及裸子植物花果和种子化石（3.8%）.结合前人在该地区发现Raphaelia diamensis，指示该套含可采煤层的细碎屑岩组合具有浓厚的中侏罗世早期的时代特征，应为中侏罗世万宝组.根据植物组合中主要发育真蕨纲的Cladophlebis，银杏纲银杏目的Ginkgo、Ginkgoites、Sphenobailra以及松柏纲苏铁衫杉科的Podozamites等分子，结合当时整个万宝组植物群面貌以及地层中含煤、发育沉积铁矿等特征，可推测研究区当时具有温暖潮湿的古气候环境.  相似文献   

考虑填充墙影响的钢筋混凝土厂房结构地震易损性分析     

梁志强  徐超  温增平 《震灾防御技术》2019,14(4):707-718

采用对角斜撑模拟纵向填充墙的作用，建立考虑填充墙和不考虑填充墙厂房结构模型，采用拉丁超立方抽样技术建立考虑材料不确定性的结构分析样本，基于随机Pushover分析确定结构不同破坏状态下的统计参数。综合考虑结构材料强度及输入地震动不确定性的影响，通过非线性时程分析开展单层钢筋混凝土厂房结构易损性研究，在此基础上比较结构横、纵向易损性的差异，研究填充墙对结构易损性的影响。研究结果表明:钢筋混凝土厂房结构体系横向地震易损性显著大于纵向地震易损性；对纵向结构体系而言，加入填充墙会明显降低结构易损性，但在相同强度的地震动作用下，填充墙破坏程度比主体结构严重，这与厂房结构的实际震害特征相符。  相似文献   

红沿河核电站取水口海冰堆积特性的离散元分析     

龙雪  季顺迎  王跃方 《海洋工程》2018,36(3):51-58

在寒冷地区,海冰在核电站取水结构物前的堆积会对取水口造成阻塞和损坏,进而影响核电设备的正常运作。以红沿河核电站的取水设施为例,综合考虑该工程海域冰区特点及风和流的作用等因素。建立了海冰的离散元模型,用于模拟海冰在结构物前的堆积和破坏过程。该离散元模型由规则排列的球体颗粒构成,颗粒间采用平行黏结模型进行黏结。考虑了海冰的平均尺寸、密集度及流速三个因素对海冰堆积过程的影响,对海冰堆积高度进行预判。其中,堆积高度随海冰的密集度和流速的增大而增大,而海冰的平均尺寸对堆积高度没有明显影响。分析结果表明,离散元数值模拟可用于评估和预测取水工程中海冰堆积造成堵塞的风险。  相似文献   

Verifying a biotope classification using benthic communities – An analysis towards the implementation of the European Marine Strategy Framework Directive     

《Marine pollution bulletin》2014,78(1-2):181-189

The HELCOM Red List biotopes project proposed a Baltic Sea wide classification consisting of six levels: The HELCOM Underwater biotopes/habitats classification system (HELCOM HUB). We present a case study from the south-western Baltic Sea where we tested the applicability of this system. More than 500 sampling stations were analyzed regarding macrozoobenthic communities and their linkage to environmental parameters. Based on the analyses of biotic and abiotic data, 21 groups were assigned to 13 biotopes of the classification. For some biotopes varying states of communities were recognized. Even though not all abiotic parameters are considered directly in the hierarchy of the classification in general, all soft-bottom communities could be allocated to a corresponding biotope. The application of the HELCOM HUB for the south-western Baltic Sea is feasible, in regard to the implementation of the European Marine Strategy Framework Directive as well as the Baltic Sea Action Plan.  相似文献   

Use of Mosses as Biomonitors of Major,Minor and Trace Element Deposition Around the Largest Thermal Power Plant in Serbia          下载免费PDF全文

Mirjana Ćujić  Snežana Dragović  Marko Sabovljević  Latinka Slavković‐Beškoski  Milan Kilibarda  Jelena Savović  Antonije Onjia 《洁净——土壤、空气、水》2014,42(1):5-11

  相似文献   

白云鄂博矿区土壤和植物中稀土元素的分布特征   总被引：2，自引：1，他引：1  

张立锋  刘杰民  张翼明 《岩矿测试》2019,38(5):556-564

白云鄂博矿区是稀土的主要产出地,在矿山开采和选炼等过程中,稀土元素通过迁移、富集等作用进入植物体,研究稀土元素的分布特征和迁移规律,可为白云鄂博矿体闭坑后的生物修复提供数据支持。本文设置了7个土壤采样点,采集铁花、沙蒿、沙打旺、沙朋、青蒿、小叶杨、猪毛菜七种植物,用电感耦合等离子体质谱法测定土壤和植物的根、茎、叶及整株的稀土含量,研究稀土元素在土壤和植物中的分布特征和迁移规律。统计分析结果表明:随着采样区与主矿区的距离增加,土壤样品中的稀土含量逐渐减少;在七种植物中,铁花的稀土含量最高,青蒿最低;对不同植物的整株稀土含量和各部位(根、茎、叶)稀土含量进行多元线性回归分析,叶(或花)的稀土含量在整珠植物中的占比最大。此外在不同季节,植物中的稀土含量基本保持不变,含量较高的稀土元素为Ce(0.0035%～0.020%)、La(0.0012%～0.011%)、Nd(0.0010%～0.0094%)和Pr(0.00036%～0.0046%),其中Ce最高。本研究提出:根据土壤样品中的稀土含量逐渐减少的特征,矿区周围土壤的稀土来源可能是矿石在采、选过程中的扩散造成的;根据植物富集稀土的能力,在矿山闭坑后,可种植富集稀土能力强的植物——铁花,进行矿山生物修复。  相似文献   

Studying Resource-Dependent Communities Through a Social-Ecological Lens? Examining Complementarity with Existing Research Traditions in Canada     

Sara Teitelbaum  Annie Montpetit  Jean-François Bissonnette  Clément Chion  Guy Chiasson  Frédérik Doyon 《社会与自然资源》2019,32(1):93-112

This article explores the suitability of Ostrom and colleagues' social-ecological systems framework (SESF) for the study of resource-dependent communities in Canada. Through a broad literature about resource-dependent communities in Canada, three main approaches are identified, named staples research, rural development, and sustainability studies. Each of these research traditions is analyzed with regards to a common set of criteria – focus, scale, methods, treatment of institutions, and treatment of environmental dimensions. Research in each category is compared and contrasted with the SESF approach, to identify areas of overlap and divergence. Results indicate that the SESF is unlikely to provide additional benefit in terms of in-depth of social analysis, however, it does provide a unique contribution in terms of its coupled approach to conceiving social and ecological systems and its ability to operationalize these relationships through structured variables.  相似文献   

How forest gaps shaped plant diversity along an elevational gradient in Wolong National Nature Reserve?     

Chen  Li  Han  Wangya  Liu  Dan  Liu  Guohua 《地理学报(英文版)》2019,29(7):1081-1097

Journal of Geographical Sciences - Understanding the underlying ecological processes that control plant diversity within (α-diversity) and among (β-diversity) forest gaps is important for...  相似文献