The influence of leaf litter diversity and soil fauna on initial soil erosion in subtropical forests   总被引：4，自引：0，他引：4       下载免费PDF全文

Steffen Seitz  Philipp Goebes  Pascale Zumstein  Thorsten Assmann  Peter Kühn  Pascal A. Niklaus  Andreas Schuldt  Thomas Scholten 《地球表面变化过程与地形》2015,40(11):1439-1447

Although the protective role of leaf litter cover against soil erosion is known for a long time, little research has been conducted on the processes involved. Moreover, the impact of soil meso‐ and macrofauna within the litter layer on erosion control is not clear. To investigate how leaf litter cover and diversity as well as meso‐ and macrofauna influence sediment discharge in subtropical forest ecosystems, a field experiment has been carried out in Southeast China. A full‐factorial random design with 96 micro‐scale runoff plots and 7 domestic leaf species was established and erosion was triggered by a rainfall simulator. Our results demonstrate that leaf litter cover protects soil from erosion (?82 % sediment discharge on leaf covered plots) by rainfall and this protection is removed as litter decomposes. The protective effect is influenced by the presence or absence of soil meso‐ and macrofauna. Fauna presence increases soil erosion rates significantly by 58 %, while leaf species diversity shows a non‐significant negative trend. We assume that the faunal effect arises from arthropods slackening and processing the soil surface as well as fragmenting and decomposing the protecting leaf litter covers. Even though the diversity level did not show a significant influence, single leaf species in monocultures show rather different impacts on sediment discharge and thus, erosion control. In our experiment, runoff plots with leaf litter from Machilus thunbergii showed the highest sediment discharge (68.0 g m^?2) whereas plots with Cyclobalanopsis glauca showed the smallest rates (7.9 g m^?2). Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

容积率对地价的作用机理及实证研究--以南京市为例   总被引：7，自引：0，他引：7  

章波  苏东升  黄贤金 《地域研究与开发》2005,24(5):105-109

文章在分析容积率对于城市地价影响的作用机理基础上,应用有关城市土地经济学理论和模型,采用边际分析方法,对南京商业、住宅、工业用地的样点数据进行实证分析。研究结果表明,城市规划与城市地价的相互关系十分复杂,但建立两者相互作用的模型是可行的,同时指出城市规划按地价理论来实施并且通过城市规划的实施促进地价空间的合理分布是必要的。研究地价、城市规划的关系,其意义不仅仅局限于如何在城市规划中充分利用地价理论优化城市土地利用结构、提高土地利用效率,同时也是为了在城市规划工作中寻找内在规律,为编制出最佳的土地利用规划及在城市中形成最佳地价空间分布及地价水平奠定基础。  相似文献   

Applicability of Wakeby distribution in flood frequency analysis: a case study for eastern Australia   总被引：1，自引：0，他引：1       下载免费PDF全文

Ataur Rahman  Mohammad A. Zaman  Khaled Haddad  Salaheddine El Adlouni  Chi Zhang 《水文研究》2015,29(4):602-614

Parametric method of flood frequency analysis (FFA) involves fitting of a probability distribution to the observed flood data at the site of interest. When record length at a given site is relatively longer and flood data exhibits skewness, a distribution having more than three parameters is often used in FFA such as log‐Pearson type 3 distribution. This paper examines the suitability of a five‐parameter Wakeby distribution for the annual maximum flood data in eastern Australia. We adopt a Monte Carlo simulation technique to select an appropriate plotting position formula and to derive a probability plot correlation coefficient (PPCC) test statistic for Wakeby distribution. The Weibull plotting position formula has been found to be the most appropriate for the Wakeby distribution. Regression equations for the PPCC tests statistics associated with the Wakeby distribution for different levels of significance have been derived. Furthermore, a power study to estimate the rejection rate associated with the derived PPCC test statistics has been undertaken. Finally, an application using annual maximum flood series data from 91 catchments in eastern Australia has been presented. Results show that the developed regression equations can be used with a high degree of confidence to test whether the Wakeby distribution fits the annual maximum flood series data at a given station. The methodology developed in this paper can be adapted to other probability distributions and to other study areas. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Effects of grass contour hedgerow systems on controlling soil erosion in red soil hilly areas,Southeast China   总被引：6，自引：0，他引：6  

Ji Fan  Lijiao Yan  Pei Zhang  Ge Zhang 《国际泥沙研究》2015,(2):107-116

Soil erosion by water is a well-recognized serious environmental problem in the world.While contour hedgerow systems are an effective method for soil water conservation,there are a few studies on its effect in the red soil hilly areas in Southeast China.With a fixed field experiment,we constructed a runoff plot at hilly area in Zhuji County,Zhejiang province,to evaluate the effect of the grass hedgerows in soil water conservation,and to determine the optimized hedgerow patterns.Hemerocallis citrine(HC)and Ophiopogon japonicas(OJ) were selected to build the hedgerows in patterns of one row and two rows.The REE method was used to trace the source of the sediment for a better understanding of the characteristic and mechanism of erosion with hedgerows control.Our results showed that(1) hedgerows reduced erosion and surface runoff by 31.99-67.22%and 15.44-45.11%,respectively;(2) hedgerows delayed the development of rills;(3) hedgerows reduced the soil nutrients loss;(4) hedgerows reshaped the soil physical properties,especially in increasing > 0.25 mm water-stable aggregates.Taken together,our results suggest that two-row OJ is the optimized contour hedgerow pattern in the experiment condition,and downward sloping land should have the highest priority to take measures for soil water conservation.This research comprehensively studied the effects and mechanism of contour hedgerows in controlling soil and water loss in red soil hilly areas,Southeast China,so that the practice of soil and water conservation can be implemented more effectively in these areas.  相似文献   

用SVG实现基于 Web的地震数据图形化服务   总被引：1，自引：0，他引：1  

牟磊育  王占英  马士振  张伟 《地震地磁观测与研究》2004,25(5):44-47

SVG是一种基于XML的用来描述二维矢量的标志语言,是一种全新的矢量图形规范,为了能够对相关人员提供方便直观快捷的地震数据表现形式,本文对利用SVG实现地震数据图形化表示的方法进行了讨论与研究。  相似文献   

Measurement of surface water runoff from plots of two different sizes   总被引：1，自引：0，他引：1  

Abraham Joel  Ingmar Messing  Oscar Seguel  Manuel Casanova 《水文研究》2002,16(7):1467-1478

Intensities and amounts of water infiltration and runoff on sloping land are governed by the rainfall pattern and soil hydraulic conductivity, as well as by the microtopography and soil surface conditions. These components are closely interrelated and occur simultaneously, and their particular contribution may change during a rainfall event, or their effects may vary at different field scales. The scale effect on the process of infiltration/runoff was studied under natural field and rainfall conditions for two plot sizes: small plots of 0·25 m² and large plots of 50 m². The measurements were carried out in the central region of Chile in a piedmont most recently used as natural pastureland. Three blocks, each having one large plot and five small plots, were established. Cumulative rainfall and runoff quantities were sampled every 5 min. Significant variations in runoff responses to rainfall rates were found for the two plot sizes. On average, large plots yielded only 40% of runoff quantities produced on small plots per unit area. This difference between plot sizes was observed even during periods of continuous runoff. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

几种土壤的细沟侵蚀过程及其影响因素   总被引：15，自引：0，他引：15       下载免费PDF全文

蔡强国  朱远达  王石英 《水科学进展》2004,15(1):12-18

通过间隔为11h的二次人工模拟降雨和冲蚀槽试验研究了10种土壤的侵蚀过程,发现在第2次降雨中大多数土壤出现了细沟侵蚀形式。采样微形态观察发现,在第1次降雨中形成结皮的土壤在第2次降雨中出现了细沟侵蚀;产流产沙观测发现所有出现细沟侵蚀的土壤在第1次降雨中径流含沙量逐渐减少,而第2次降雨中有一个先剧增后减少的过程。土壤理化分析及多元逐步回归分析结果表明,土壤颗粒组成、有机质含量、铁铝含量等因素对细沟侵蚀的影响表现不明显,而与土壤团聚体有关结构指标、细沟侵蚀、产流产沙速率及总量呈显著相关关系。分析表明,团聚体分散度、崩解速率与渗透系数之比两个指标能较好地预测细沟侵蚀发生的可能性,同时也能很好地预测侵蚀产沙量。  相似文献   

Magnetic interaction analysis of basaltic samples and pre-selection for absolute palaeointensity measurements     

Florian Wehland  Roman Leonhardt  Fabienne Vadeboin  Erwin Appel 《Geophysical Journal International》2005,162(2):315-320

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改良的数字化测图新方法     

余代俊  熊伟 《四川地震》2005,(4):21-24

阐述了在地形复杂、地貌破碎、作业组较多时一种改良的数字化测图新方法的作业流程。该方法发挥了数字化测图的高精度高效率和模拟法测图善于处理勾绘复杂地貌等高线的长处，为针对不同情况制定合适的测图作业方案增加了一种选择。  相似文献   

基于Microstation图形工作站的城区防洪图的设计与编制     

朱晓青 《测绘学院学报》1997,(3)

本文从城市体系的构成出发，论述了城区防洪图的组成。结合《江苏省水利地图集》的制作，对该图种的用途、要求、资料使用情况及作业方法都作了简要说明；详细介绍了城区防洪图的编绘内容及表示方法。最后基于Microstation工作站，从符号系统、截幅到编绘效率及编绘过程中几个实际问题作了具体分析。  相似文献