Taxonomy for surveying the use and value of geographical information!     

HUGH W. CALKINS  NANCY J. OBERMEYER 《International journal of geographical information science》2013,27(3):341-351

Abstract

Understanding the use and value of geographical information in decision making has been identified as crucial to the further development of geographical information systems and related spatial analysis techniques. Research into the use of geographical information will be through surveys and case studies. A taxonomy for investigating the use of geographical information and its associated value is needed to structure the surveys and case studies. This paper presents an initial attempt at such a taxonomy, intended to support continuing research into the use and value of geographical information. The survey methodology to be supported will be mostly telephone and/or mail questionnaires, and this has influenced the structure of the taxonomy. The goal of this work is to create a taxonomy suitable for use in surveys that will enhance the understanding of the use and value of geographical information in decision making.  相似文献   

Regionalization with dynamically constrained agglomerative clustering and partitioning (REDCAP)     

D. Guo 《International journal of geographical information science》2013,27(7):801-823

Regionalization is to divide a large set of spatial objects into a number of spatially contiguous regions while optimizing an objective function, which is normally a homogeneity (or heterogeneity) measure of the derived regions. This research proposes and evaluates a family of six hierarchical regionalization methods. The six methods are based on three agglomerative clustering approaches, including the single linkage, average linkage (ALK), and the complete linkage (CLK), each of which is constrained with spatial contiguity in two different ways (i.e. the first‐order constraining and the full‐order constraining). It is discovered that both the Full‐Order‐CLK and the Full‐Order‐ALK methods significantly outperform existing methods across four quality evaluations: the total heterogeneity, region size balance, internal variation, and the preservation of data distribution. Moreover, the proposed algorithms are efficient and can find the solution in O(n ²log n) time. With such data scalability, for the first time it is possible to effectively regionalize large data sets that have 10 000 or more spatial objects. A detailed comparison and evaluation of the six methods are carried out with the 2004 US presidential election data.  相似文献   

A regionalization method for clustering and partitioning based on trajectories from NLP perspective     

Yizhuo Li  Fan Zhang 《International journal of geographical information science》2013,27(12):2385-2405

ABSTRACT

Regionalization attempts to group units into a few subsets to partition the entire area. The results represent the underlying spatial structure and facilitate decision-making. Massive amounts of trajectories produced in the urban space provide a new opportunity for regionalization from human mobility. This paper proposes and applies a novel regionalization method to cluster similar areal units and visualize the spatial structure by considering all trajectories in an area into a word embedding model. In this model, nodes in a trajectory are regarded as words in a sentence, and nodes can be clustered in the feature space. The result depicts the underlying socio-economic structure at multiple spatial scales. To our knowledge, this is the first regionalization method from trajectories with natural language processing technology. A case study of mobile phone trajectory data in Beijing is used to validate our method, and then we evaluate its performance by predicting the next location of an individual’s trajectory. The case study indicates that the method is fast, flexible and scalable to large trajectory datasets, and moreover, represents the structure of trajectory more effectively.  相似文献   

陕北黄土高原土地类型区域分异规律遥感分析     

陈楚群  陈捷 《遥感学报》1992,(1)

陕北黄土高原地形破碎、交通不便、土地利用不合理、水土流失严重、生态环境脆弱。为了扭转这种局面,必须查清区内土地资源的类型及其分布状况,以便合理地评价和利用土地资源,改善当地的经济状况和生态环境。 本文以陕北11个县(市)为例,对利用TM图像进行1:10万土地类型遥感调查与制图的工作方法和程序进行了讨论,对区内土地类型区域分异因素和分异规律进行了分析,并在此基础上,提出了土地类型分区及分区治理措施的建议。  相似文献   

中国近50年降水量变化区划(1961-2010年)   总被引：2，自引：0，他引：2  

梁圆  千怀遂  张灵 《气象学报》2016,74(1):31-45

基于中国537个气象站点1961-2010年的年降水量数据,运用滑动概率分布模型、小波分析和Mann-Kendall检验法,结合中国地形特点,从降水量均值的变化、变率的变化、频率分布形式的变化、突变特征以及周期变化5个方面来分析中国降水量的变化特征和区域差异,构建具体的指标体系,对中国降水量变化进行区划。结果表明,中国降水量变化存在明显的区域差异,根据这些差异可以将中国划分为3个变率变化带、10个平均降水量变化区、35个周期变化亚区。   相似文献   

Developing a flow-based spatial algorithm to delineate hospital service areas     

《Applied geography (Sevenoaks, England)》2016

Hospital service areas (HSAs) capture most of local patient-to-hospital travel flows, and have been accepted as the most basic unit for analyzing local hospital utilization and hospitalization patterns. If a given HSA includes multiple hospitals providing care for its residents, it is complicated to assign responsibility for small-area variation in hospital performance or healthcare costs to specific hospitals without established HSA managers. The goal of this study is to produce HSAs with the fewest number of hospitals within an HSA unit. Only a very limited number of studies are related to the HSA delineation. This study reviews the existing approaches to delineate a broader range of service areas besides HSAs. A spatial algorithm named Travel-to-Hospital Algorithm (TTHA) was developed and implemented using the individual hospital discharge records from the Florida State Inpatient Database for 2011. The final output, named the TTHA-derived HSAs, included 14 more eligible divisions in Florida than the HSAs produced by the traditional approach (92 vs. 78), with the degree of self-containment comparable between the two sets of HSAs. The TTHA provides insight into the patterns of hospital visits and holds great value for the delineation of other types of service and catchment areas.  相似文献   

中国人口的分布、区划和展望   总被引：15，自引：10，他引：15  

胡焕庸 《地理学报》1990,(2)

我国地势西高东低。东部第一台阶为湿润的平原和丘陵,人口稠密。第二台阶分布在中部和西北部,大部为干旱半干旱气候。西南部的青藏高原属高寒气候,人口稀少。一条分界线东北起于黑龙江省的黑河,西南至云南省的腾冲。此线以东居住着全国96％的人口。以西居住着4％的人口。作者把全国分为八大人口区。在未来岁月里,我国人口分布的总格局不会有很大改变。  相似文献   

陕西省地质灾害区划及活动规律统计分析     

程谦恭  杨铭君  苏宝怀  赵淑芳  徐继刚 《地球科学与环境学报》1995,(1)

本文对陕西省主要地质灾害类型进行了综合区划，分出８个大的灾害区及５２个次一级灾害亚区。灾害规律统计分析表明：在空间上，区域性滑坡等灾害类型的群体发育受新构造应力场的制约，高频率优势事件往往是沿新构造应力网络中一组最大剪切面方向或主张应力方向出现；在时间上，灾害事件显示多层次多尺度群发期及周期序列，表现为具有２７０ａ的长周期及９～１３ａ、４～６ａ的短周期．  相似文献   

Regionalization of constraints on expected watershed response behavior for improved predictions in ungauged basins   总被引：2，自引：0，他引：2  

Maitreya Yadav  Thorsten Wagener  Hoshin Gupta 《Advances in water resources》2007

Approaches to modeling the continuous hydrologic response of ungauged basins use observable physical characteristics of watersheds to either directly infer values for the parameters of hydrologic models, or to establish regression relationships between watershed structure and model parameters. Both these approaches still have widely discussed limitations, including impacts of model structural uncertainty. In this paper we introduce an alternative, model independent, approach to streamflow prediction in ungauged basins based on empirical evidence of relationships between watershed structure, climate and watershed response behavior. Instead of directly estimating values for model parameters, different hydrologic response behaviors of the watershed, quantified through model independent streamflow indices, are estimated and subsequently regionalized in an uncertainty framework. This results in expected ranges of streamflow indices in ungauged watersheds. A pilot study using 30 UK watersheds shows how this regionalized information can be used to constrain ensemble predictions of any model at ungauged sites. Dominant controlling characteristics were found to be climate (wetness index), watershed topography (slope), and hydrogeology. Main streamflow indices were high pulse count, runoff ratio, and the slope of the flow duration curve. This new approach provided sharp and reliable predictions of continuous streamflow at the ungauged sites tested.  相似文献   

Identification of basin characteristics influencing spatial variation of river flows     

Dominic Mazvimavi  Saskia L.G.E. Burgers  Alfred Stein 《International Journal of Applied Earth Observation and Geoinformation》2006

The selection of basin characteristics that explain spatial variation of river flows is important for hydrological regionalization as this enables estimation of flow statistics of ungauged basins. A direct gradient analysis method, redundancy analysis, is used to identify basin characteristics, which explain the variation of river flows among 52 selected basins in Zimbabwe. Flow statistics considered are mean annual runoff, coefficient of variation of annual runoff, average number of days per year without flow and selected percentile flows. Basin characteristics investigated are those likely to reflect climatological, topographical and hydrogeological influences including that of land cover on river flows. The first ordination axis of flow statistics is strongly correlated with mean annual precipitation, mean annual potential evaporation and median slope. This ordination axis explains 64% of the variation of selected flow statistics among the selected drainage basins. The proportions of a basin under cultivation, and that with grasslands are correlated with the second ordination axis, which explains 6% of the variation of selected flow statistics. Mean annual precipitation is the most important basin characteristic, and this alone explains 50% of the variation of flow statistics. Median slope is the second most important basin characteristic. Proportions of a basin underlain by different lithological types had no effect on flow characteristics of selected basins. The paper has demonstrated the ability of redundancy analysis to identify basin characteristics that explain the variation of river flows among basins, including estimating the relative importance of these basin characteristics.  相似文献