基于SRTM-DEM和TM的流动沙丘提取方法研究   总被引：1，自引：0，他引：1  

柴慧霞  刘海江  周成虎  陈曦  程维明  王睿博 《干旱区资源与环境》2009,(9)

以塔克拉玛干沙漠的流动沙丘地貌为例,进行数字地貌形态提取方法研究。首先,利用高精度Srtm-DEM数据派生出坡度和起伏度两个地形因子数据,并参考坡度和起伏度的分类指标,实现沙地和沙丘边界线的自动提取,将风成地貌按照形态特征区分出沙地和沙丘两种地貌类型。其次,利用数学分析方法,根据斑块指数值的大小初步确定复合流动沙丘的类型。最后,基于高空间分辨率的遥感影像的色调、纹理、结构等特征,建立典型流动沙丘地貌特征的遥感影像特征图谱,依据遥感图谱进一步确定复合流动沙丘的类型,实现典型复合流动沙丘地貌形态和成因特征的计算机智能化提取方法。研究结果表明:该方法目前可以实现流动沙丘中的复合型链垄状沙丘、复合型沙垄、穹状沙丘和蜂窝状沙丘的智能化提取。  相似文献   

Evolution of the Minangkabau's shifting cultivation in the West Sumatra highland OF Indonesia and its strategic implications for dynamic farming systems     

A. Dendi  G. P. Shivakoti  R. Dale  S. L. Ranamukhaarachchi 《Land Degradation \u0026amp; Development》2005,16(1):13-26

This paper explores the evolution of the shifting cultivation of the Minangkabau , the biggest matrilineal society in Indonesia, and examines factors underlying the instability and vulnerability of farmers' livelihoods and the degradation of their resource base using an extended factor analysis technique, in order to understand how development strategies might be modified towards a more dynamic farming system. The study distinguished three main phases of the farming system's changes and found that these changes highly corresponded with the emerging market and institutional incentives. Furthermore, the factor analysis generated a six‐factor model suggesting strategic interventions to foster the improvement of farmers' livelihoods and environment in future. In addition, consistent with the results of these factors analysis, we argue that, provided land tenure is conducive, there are substantial possibilities for policies and interventions that focus first on agricultural diversification and then on organization building, to assist in dealing with farmers' vulnerability and environmental degradation in the uplands. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

基于最优潮流并计及TCPST的可用输电能力计算     

王俊  吴秀华  王思宇  谢飞  吴修世 《沈阳农业大学学报》2008,39(6)

基于最优潮流(OPF)方法.将可用输电能力的计算转化为求解多约束的非线性规划问题,建立了计及品闸管控制的移相器(TCPST)的ATC计算模型.利用功率注入法将TCPST对电网的控制作用通过对相关节点的等效注入功率来体现,从而使与TCPST关联的节电导纳矩阵南非对称阵变为对称阵.进而大大简化了潮流计算程序.在算法上采用半光滑牛顿算法,IEEE30节点系统的计算结果表明,所提出的模型及算法正确.  相似文献   

塔克拉玛干沙漠腹地高大复杂纵向沙垄区简单横向沙丘形态特征的空间变异   总被引：1，自引：0，他引：1  

范冬冬  李生宇  雷加强  徐新文  孙艳伟  代述勇  谷峰  邱永志  张忠良  刘保松 《干旱区研究》2009,26(5)

为了探讨小尺度风沙地貌形态的空间变异过程,对塔克拉玛干沙漠腹地高大复杂纵向沙垄横断面上简单横向沙丘形态特征进行了研究。沙丘形态野外测量采用RTK(real-tim e k inem atic)技术,并通过南方测绘软件(South Survey)量算形态特征参数。结果表明:简单横向沙丘形态特征参数及其相互关系具有空间变异性。在8个地貌部位之间,沙丘形态特征参数(不包括迎风坡度)存在显著性差异,主要体现在:垄顶、沙垄背风坡、其他地貌部位(包括垄间地和沙垄迎风坡)三者之间的差异。地貌部位、输沙风强度以及沙丘活动强度是驱动沙丘形态空间变异的因素。沙丘高度与翼展度余弦有负对数关系,发育指数与高度、迎风坡度成负线性相关,这些相关性的显著程度在垄顶、背风坡较高,在垄间和迎风坡较低。  相似文献   

吉林西部沙丘区造林树种在干旱——补水循环条件下生长率的比较     

韩国辉  韩国君 《吉林林业科技》2000,29(5):5-7

本文对５个树种在干旱－－补水循环条件下各器官的生长状况进行了调查,并对各权种间的生长率情况进行了比较。结果表明,杨树、樟子松、长白松和沙棘补水后短期内生长明显加快,其生长率由大到小的顺序为：沙棘〉杨树〉长白松〉樟子松。而经济树种枸杞反映不明显。  相似文献   

洛阳市土石山区小流域治理经验     

张军校  常黑林 《中国水土保持》1995,(4):54-55

洛阳市土石山区小流域治理经验张军校，常黑林（河南省洛阳市水利水产局，４７１０００）洛阳市地处河南省的西部，总面积１５１６０ｋｍ２，水土流失面积１０４４４ｋｍ２，全市土石山区面积约８８２９ｋｍ２，其中水土流失面积为６０８０ｋｍ２，截至１９９４年底已治理...  相似文献   

Simulated impact of sea level rise on phreatic level and vegetation of dune slacks in the Voorne dune area (The Netherlands)     

V. Noest 《Landscape Ecology》1991,6(1-2):89-97

Effects of sea level rise and different coastline management options on the phreatic level in a coastal dune area are calculated, using a scenario with 60 cm sea level rise in the course of the next century, resulting from global climatic changes. Changes in the phreatic level - both lowering and rising - are evaluated for their effects on the dune slack vegetation, using a newly developed interaction model hydrology-vegetation. Some indications of changes in nature conservation values are presented.  相似文献   

疏勒河中游盐质沙丘分布长穗柽柳种群空间格局及种间联结性研究   总被引：1，自引：0，他引：1  

方敏彦  丁品  张德罡 《畜牧与饲料科学》2008,29(6)

在中点四分法调查资料的基础上,阐述了疏勒河中游流域盐质沙丘分布长穗柽柳群落结构组成:并采用离散分布模型的理论拟合、聚集强度指标和种间联结测定等方法,研究了该群落类型优势种的空间分布格局和种间生态分布的联结关系.  相似文献   

Agroforestry practices in Nigeria     

J. O. Adegbehin  A. B. I. Igboanugo 《Agroforestry Systems》1990,10(1):1-22

The problems of too much pressure on land for the production of food and wood for the increasing population have made it mandatory to look into the various ways of maximising the uses of agricultural land in different parts of the world. Under this high demand for land, the system of shifting cultivation which has been practised from time immemorial can no longer support the needs of farmers in Nigeria. As a result of this, the different agroforestry practices have received increased attention. The experiences obtained with shifting cultivation, homestead gardens, taungya, alley-farming and scattered farm tree methods including shelterbelt planting in the country are reviewed in this paper and some research findings on these practices are highlighted.  相似文献   

Farmer adoption of contour hedgerow intercropping,a case study from east Indonesia     

K. F. Wiersum 《Agroforestry Systems》1994,27(2):163-182

The results of a study to assess the initial impact of the introduction of contour hedgerow intercropping on the Indonesian islands of Lombok and Sumbawa are described. The study focused on the reasons for adopting this technique and its initial effect. The results of detailed case studies in four villages indicated that the process of adoption is heterogeneous. Land-use conditions in the four villages were much more diverse and dynamic than the project anticipated. Rather than being an off the shelf technique as assumed by the project, hedgerow cropping proved to be a prototype technique; the farmers' ability to adapt the practice to their specific farming conditions such as subsistence food production or cash crop cultivation was an important motive for its adoption. In some cases the introduction competed with the extension of other promising land-use practices. Several farmers adopted the technique not because of its productive benefits, but as a means to gain access to land or credit, or to demonstrate their allegiance to social networks. The results indicate that there were significant discontinuities between what the project intended to achieve by introducing the technique and the farmers' motives for adopting it.  相似文献