北京市平原区小流域划分技术研究     

冯学兵  任海英  马福光  王淼 《北京测绘》2012,(6):34-36,59

流域是水利现代化管理与精细化管理的重要基础,小流域是对流域的进一步细化。本文首先阐述了小流域的概念,接着结合实际需求,分析讨论了北京市平原区内小流域划分技术及原则,最后对北京市平原区的小流域划分结果进行展示和讨论,并分析了小流域成果应用方向。  相似文献   

基于DEM的平缓地区水系提取和流域分割的流向算法分析   总被引：3，自引：0，他引：3  

张维  杨昕  汤国安  祝士杰  李彩丽 《测绘科学》2012,37(2):94-96

本文以地势较为平坦的秦淮河流域为实验样区,以高精度DEM(5m分辨率)和地形图水系为基础数据,对比分析了单流向算法(D8算法)、多流向算法(Dinf法)以及添加数字化河道信息后的单流向算法(AgreeD8算法)3种算法下水系提取和流域分割的结果。实验结果表明,提取得到的水系更逼近于实际河网,该算法既有效提高了水系提取和流域分割的精度,又保留了D8算法模型简单、稳定性强、运行效率高等优点。  相似文献   

Reflecting on Role Play in Geographic Education: The Case of the Banana War     

《The Journal of geography》2012,111(1):16-27

Abstract

Debates over the nature and extent of globalization raise many issues to be addressed in a geographic education. In this paper, I briefly review case method instruction and role-play as teaching strategies suitable for material on globalization and other geographic subject matter, and then sketch an overview of an undergraduate geography role-play that treats themes of globalization and agricultural trade. The role-play revolves around a real-world trade dispute, referred to as the Banana War, that was waged between the United States and the European Union during much of the 1990s over who could sell how many bananas to Europe. I conclude the paper by reflecting on the contributions of, limitations to and possibilities for case method instruction and role-play in geographic education.  相似文献   

Implementing a national environmental policy: Understanding the ‘success’ of the 1989–1999 integrated pest management programme in Indonesia     

Budy P. Resosudarmo 《Singapore journal of tropical geography》2012,33(3):365-380

The fact that most environmental degradation occurs in developing countries suggests the difficulties in implementing and sustaining environmental policies. In the current era of heightened environmental awareness and publicity for the impacts of climate change, where all countries are expected to take action, cases of ‘successful’ implementations of environmental policy in a developing country are instructive. This paper provides an overview of why and how the 1989–1999 national integrated pest management programme worked in Indonesia – before being terminated in the wake of the Asian financial crisis. It is seen that environmental programmes cannot be sustained without strong national political endorsement, focussed local research linked to international support, appropriate policy implementation mechanisms and demonstrated and direct benefits for local participants and communities.  相似文献   

中国东南地区源头溪流五川流域的氮饱和特征     

王飞飞  曹文志  李颖  苏彩霞  陈劲松 《亚热带资源与环境学报》2012,7(2)

以九龙江流域典型的农业源头溪流——五川溪为研究区域,开展每月一次共2年的NO,一采样用于溪流氮饱和特征的研究．结果表明,2005年和2007年溪流的NO,一浓度分别为35．5～319．5μeqL^-1和5．0～353．6μxeqL^-1,根据Stoddard和Traaen提出的氮饱和划分准则,五川流域分别处于氮饱和阶段2／3和阶段2,接近氮饱和．氮饱和阶段随着NO。一浓度的增加而上升,五川溪流的氮饱和阶段存在着时间上的变化．河流生态系统中氮负荷增加,使河流达到氮饱和状态,并最终改变溪流系统硝化和反硝化等氮的生物地球化学循环过程．随着NO,一浓度的增加,五川源头溪流已成为流域内重要的NO3^-源．  相似文献   

Morphometric analysis of a watershed of South India using SRTM data and GIS   总被引：3，自引：0，他引：3  

P. D. Sreedevi  S. Owais  H. H. Khan  S. Ahmed 《Journal of the Geological Society of India》2009,73(4):543-552

An attempt has been made to study drainage morphometry and its influence on hydrology of Wailapalli watershed, South India. For detailed study we used Shuttle Radar Topographic Mission (SRTM) data for preparing Digital Elevation Model (DEM), aspect grid and slope maps, Geographical information system (GIS) was used in evaluation of linear, areal and relief aspects of morphometric parameters. The study reveals that the elongated shape of the basin is mainly due to the guiding effect of thrusting and faulting. The lower order streams are mostly dominating the basin. The development of stream segments in the basin area is more or less affected by rainfall. The mean Rb of the entire basin is 3.89 which indicate that the drainage pattern is not much influenced by geological structures. Relief ratio indicates that the discharge capability of these watersheds is very high and the groundwater potential is meager. These studies are very useful for planning rainwater harvesting and watershed management.  相似文献   

山东省基本农田可持续利用研究     

许庆福  ;韩颖新 《山东地质》2009,(7):49-51

分析了山东省基本农田的数量、分布和构成状况,对1997--2005年全省及各市的基本农田面积变化情况进行对比,指出基本农田保护中存在的问题及面临的形势,提出实现基本农田可持续利用的对策：数量、质量和环境全面管护;经济效益、社会效益和环境效益相统一;用养结合、保持地力、提高产出水平;划定整备区、储备待补资源;区别对待、协调发展。  相似文献   

数字化流域及流域信息提取方法研究   总被引：3，自引：0，他引：3  

翁明华  姚成  李致家 《水文》2009,29(5)

介绍了基于数字高程模型(DEM)的流域信息提取方法,包括:DEM预处理,流向及集水面积的确定,水系的生成及子流域的划分方法以及流域面积、长度、坡度、坡向等信息的提取.并将这些方法应用于安徽境内的呈村流域,进行了实例验证,构建了数字化流域.  相似文献   

Spatial-temporal change in urban agricultural land use efficiency from the perspective of agricultural multi-functionality: A case study of the Xi’an metropolitan zone   总被引：4，自引：1，他引：3  

Zhongxue Zhou  Mengtao Li 《地理学报(英文版)》2017,27(12):1499-1520

The excessive expansion of urbanized areas has resulted in haphazard land utilization, immoderate consumption of superior agricultural land and water resources, significant fragmentation of agricultural landscape, and gradual deterioration of the agro-ecological environment. Combined, these factors cause poor land use efficiency. Under these circumstances, comprehensively assessing land use efficiency for urban agriculture is a key issue in land use research. Currently, evaluation methods for agricultural land use efficiency narrowly concentrate on aspects of economic input and output. However, urban agro-ecosystems can provide diverse economic, social, and ecological services and functions. In particular, the social and ecological services and functions originating from agricultural land, which have a higher value than economic services, play a significant role in ensuring regional social, ecological, and environmental security. However, recent research has rarely taken these benefits into consideration. Therefore, land use value has been greatly underestimated, which has resulted in mishandled and poor land use policies. In this study, we apply Landsat imagery and social and economic statistical data for the Xi’an metropolitan zone (XMZ) to investigate agricultural multi-functionality. We develop an evaluation framework for urban agricultural land use efficiency and identify agro-ecosystem services and functions as important outputs from agricultural land. The land use efficiency of urban agriculture is then evaluated using ecosystem services models, providing a mechanism for assessing spatial-temporal changes in land use efficiency in the XMZ from 1999 to 2015. Four important conclusions are reached from this analysis. First, the rapid urbanization and agricultural transformation from traditional cereal cultivation to modern urban agriculture has resulted in steadily increasing costs, outputs, and land use efficiency of urban agriculture. The total output value increased 41% and land use efficiency per hectare increased by 33.13% on average. Second, the spatial patterns of comprehensive output and land use efficiency were dominated by economic outputs from agricultural land. Areas near cities, which are dominated by orchard and arable land, provide more economic functions. These areas support and regulate services due to the transformation from extensive cereal production to intensive modern urban agriculture; therefore, they have higher output value and land use efficiency. In contrast, areas distant from cities, towns, and high traffic roads, namely, remote rural areas, provide more support and regulating services, but have relatively lower economic function due to inaccessibility to urban markets and slow agricultural transformation. Therefore, these areas have lower output value and land use efficiency. The spatial change in agricultural output and land use efficiency in urban areas is strongly dependent on the degree of urbanization and agricultural transformation. Third, the total output value and land use efficiency of urban agriculture measured with our approach are much higher than evaluations using traditional methods. However, the spatial patterns measured using the two approaches are in agreement. The evaluation framework integrates ecological services and economic and social functions into a comprehensive output from agricultural land. This approach is more methodical and accurate for evaluating the comprehensive efficiency of land use based on quantities and spatial scale because they are at the pixel scale. Finally, the evaluation results have important implications for enhancing current agricultural subsidies and even implementing ecological payment policies in China. Most importantly, they can be directly applied to agricultural transformation regulations, decision- making, and guidance for rational land utilization.  相似文献   

Impacts of Non-farm Employment of Rural Laborers on Agricultural Land Use: Theoretical Analysis and Its Policy Implications     

HAO Haiguang  LI Xiubin  XIN Liangjie 《资源与生态学报(英文版)》2017,8(6):595-604

During rapid urbanization and industrialization process, non-farm employment of rural laborers has emerged as a prevalent phenomenon in rural areas of China and become an important driving factor for changes in agricultural land use. This article attempts to theoretically analyze the impacts of non-farm employment of rural laborers on agricultural land use based on economic frameworks. As rational agents, farmers aim to maximize their income and follow equilibrium principles when they decide how to allocate their labor forces (or working time) in two departments (farm and non-farm) and how to use their agricultural land with different quality and location. The income earned by non-farm employment is higher, and there exists a comparative advantage between labors, as a result the quantity and quality of labor input in agricultural land use decreases. With the limitation of labor input during agricultural land use decision-making of farm households, on the one hand, land with higher quality is still utilized by farmers. On the other hand, poor quality land will be less well managed and is more likely to be abandoned. Non-farm employment of rural laborers and the rising of opportunity costs will result in abandonment of poor quality land, and great importance should be attached to this by policy makers.  相似文献