Spatial patterns of adolescent drug use     

《Applied geography (Sevenoaks, England)》2015

Adolescent drug use is individually and socially harmful in terms of disrupting adolescent development and social cohesion. Prior research has identified populations at risk and risk factors for adolescent drug use. This research sought to contextualize adolescent drug use by examining this behavior from a geographic perspective. The specific objectives were to identify patterns, local clusters and excess spatial risk for 5-digit zip codes within the 5-county Cincinnati, Ohio region. Adolescents (n = 57,241) were recruited within local schools by the Coalition for a Drug-free Greater Cincinnati. Results of this research show spatial clusters for perceived safety of marijuana; peer approval of alcohol, tobacco and marijuana; and age of onset for other drugs. The location and nature of these clusters are discussed and displayed in-text. Further, zip codes that were in excess risk compared to the 5-county region were identified. The utility of this research is two-fold: (1) It identifies the geographic variability in adolescent drug use and correlated factors of use, and (2) It provides a methodological framework for future research in spatial epidemiology of drug use.  相似文献   

Converting Brazil's pastures to cropland: An alternative way to meet sugarcane demand and to spare forestlands     

《Applied geography (Sevenoaks, England)》2015

Brazil seeks to rapidly increase its agricultural production to meet future demands, especially for sugarcane, which is an agricultural commodity and a biofuel source. In this paper, we explore how to achieve this increase without compromising existing forestlands. We propose that it is possible to substantially expand sugarcane production in Brazil while avoiding further environmental losses and the indirect land use changes often associated with them, such as deforestation. This task could be accomplished by converting existing pasturelands with agricultural potential into cropland. A great deal of pastureland exists in Brazil. Thus, we addressed the following questions in this study: (1) where are the most suitable pasturelands for sugarcane located geographically and (2) what potential do these pasturelands have for sugarcane production regarding their physical suitability and other significant factors, such as infrastructure availability and socioeconomic factors. We conducted a land suitability analysis using a spatial location model based on multicriteria decision-making and geographic information systems (GIS) to identify the cultivated pasturelands most suitable for conversion to sugarcane production in Brazil. “What if” scenarios were built to determine how changes in the subjectively derived weights of the priority criteria would modify the spatial distribution of the suitability classes relative to the MCDA model and demonstrate the robustness of the crop suitability assessment. The most suitable pastureland areas for conversion to sugarcane production were predominantly located in Minas Gerais, São Paulo, Paraná, Goiás, Mato Grosso do Sul, Mato Grosso and Pará. These zones have large contiguous areas of pasture with moderate and high agricultural potentials for sugarcane production. The total estimated area of cultivated pasturelands with moderate or high suitability for sugarcane production was 50 million hectares, which is much larger than the area currently used for sugarcane production in Brazil.  相似文献   

Linking pesticides and human health: A geographic information system (GIS) and Landsat remote sensing method to estimate agricultural pesticide exposure     

《Applied geography (Sevenoaks, England)》2015

Accurate pesticide exposure estimation is integral to epidemiologic studies elucidating the role of pesticides in human health. Humans can be exposed to pesticides via residential proximity to agricultural pesticide applications (drift). We present an improved geographic information system (GIS) and remote sensing method, the Landsat method, to estimate agricultural pesticide exposure through matching pesticide applications to crops classified from temporally concurrent Landsat satellite remote sensing images in California. The image classification method utilizes Normalized Difference Vegetation Index (NDVI) values in a combined maximum likelihood classification and per-field (using segments) approach. Pesticide exposure is estimated according to pesticide-treated crop fields intersecting 500 m buffers around geocoded locations (e.g., residences) in a GIS. Study results demonstrate that the Landsat method can improve GIS-based pesticide exposure estimation by matching more pesticide applications to crops (especially temporary crops) classified using temporally concurrent Landsat images compared to the standard method that relies on infrequently updated land use survey (LUS) crop data. The Landsat method can be used in epidemiologic studies to reconstruct past individual-level exposure to specific pesticides according to where individuals are located.  相似文献   

Progress and prospect of research on forest landscape model     

DAI Erfu  WU Zhuo  WANG Xiaofan  FU Hua  XI Weimin  PAN Tao 《地理学报》2015,25(1):113-128

The Forest Landscape Model (FLM) is an efficiency tool of quantified expression of forest ecosystem''s structure and function. This paper, on the basis of identifying FLM, according to the stage of development, summarizes the development characteristics of the model, which includes the theoretical foundation of mathematical model, FLM of stand-scale, primary development of spatial landscape model, rapid development of ecosystem process model as the priority, and developing period of structure and process driven by multi-factor. According to the characteristics of different FLMs, this paper classifies the existing FLM in terms of mechanism, property and application, and elaborates the identifications, advantages and disadvantages of different types of models. It summarizes and evaluates the main application fields of existing models from two aspects which are the changes of spatial pattern and ecological process. Eventually, this paper presents FLM''s challenges and directions of development in the future, including: (1) more prominent service on the practical strategy of forest management''s objectives; (2) construction of multi-modules and multi-plugin to satisfy landscape research demand in various conditions; (3) adoption of high resolution''s spatial-temporal data; (4) structural construction of multi-version module; (5) improving the spatial suitability of model application.  相似文献   

Spatiotemporal patterns of tropical deforestation and forest degradation in response to the operation of the Tucuruí hydroelectric dam in the Amazon basin     

《Applied geography (Sevenoaks, England)》2015

The planned construction of hundreds of hydroelectric dams in the Amazon basin has the potential to provide invaluable ‘clean’ energy resources for aiding in securing future regional energy needs and continued economic growth. These mega-structures, however, directly and indirectly interfere with natural ecosystem dynamics, and can cause noticeable tree loss. To improve our understanding of how hydroelectric dams affect the surrounding spatiotemporal patterns of forest disturbances, this case study integrated remote sensing spectral mixture analysis, GIS proximity analysis and statistical hypothesis testing to extract and evaluate spatially-explicit patterns of deforestation (clearing of entire forest patch) and forest degradation (reduced tree density) in the 80,000 km² neighborhoods of the Brazil's Tucuruí Dam, the first large-scale hydroelectric project in the Amazon region, over a period of 25 years from 1988 to 2013. Results show that the average rates of deforestation were consistent during the first three time periods 1988–1995 (620 km² per year), 1995–2001 (591 km² per year), and 2001–2008 (660 km² per year). However, such rate dramatically fell to half of historical levels after 2008, possibly reflecting the 2008 global economic crisis and enforcement of the Brazilian Law of Environmental Crimes. The rate of forest degradation was relatively stable from 1988 to 2013 and, on average, was 17.8% of the rate of deforestation. Deforestation and forest degradation were found to follow similar spatial patterns across the dam neighborhoods, upstream reaches or downstream reaches at the distances of 5 km–80 km, suggesting that small and large-scale forest disturbances may have been influencing each other in the vicinity of the dam. We further found that the neighborhoods of the Tucuruí Dam and the upstream region experienced similar degrees of canopy loss. Such loss was mainly attributed to the fast expansion of the Tucuruí town, and the intensive logging activities alongside major roads in the upstream reservoir region. In contrast, a significantly lower level of forest disturbance was discovered in the downstream region.  相似文献   

Mediterranean cities under fire. A critical approach to the wildland–urban interface     

《Applied geography (Sevenoaks, England)》2015

Wildfires are widely reviewed as key inputs to Mediterranean ecosystems. However, research is often flawed by major biases. (1) The approach adopted by most planners focusing on forest fires dismisses the human dimension of fire as a component of agricultural production systems. (2) The Wildland–Urban Interface (WUI) concept postulates that cities and wildlands/wildfires are, and should remain, worlds apart, a statement whose truth is increasingly questioned by recent disastrous “urban wildfires”. (3) The Mediterranean Basin as a fire-prone area is all the more fantasized, as it is almost never studied as a whole.The present paper takes a critical view of city–wildland/wildfire interrelationships through a large-scale study of the Mediterranean Basin based on MODIS MCD12Q1 (Land Cover Type) and MCD45A1 (Burned Area Product) data collected between 2001 and 2013. The Mediterranean is an ideal place to investigate, as its human-dominated and urbanized landscapes are known to be extremely vulnerable to fire hazards. Data processing reveals that (wild)fires and cities maintain indissoluble ties, as if both elements could not be considered mutually exclusive on a geographical basis. Urban sprawl, reduced rural autonomies, changes in forest covers, old agricultural practices, and military conflicts provide the framework for an extended mitigation process challenging the WUI concept as a space divider.  相似文献   

农村居民点动态演变及驱动机制研究——以江苏省宜兴市为例     

赵冰雪  夏敏  符海月 《地域研究与开发》2015,(1)

选取宜兴市为研究区,在GIS和RS技术的支撑下,对农村居民点用地的规模变化和空间分布进行分析,对引起农村居民点用地变化的驱动因素进行研究。结果表明:1农村居民点用地整体呈下降趋势,变化速度逐年减慢,主要新增来源是农用地,主要转移去向是城镇建设用地;2在地形平坦、距离水源和农用地较近的地区,农村居民点分布密集;3经济发展、人口减少、交通改善和城市化水平提高是影响农村居民点变化的主要驱动因素。  相似文献   

组团城市公交线网结构特征研究——以四川省南充市为例     

段含明 《地域研究与开发》2015,(3):79-84

以四川省南充市为例,从城市公交线路统计指标和线路网空间分布特征角度,定量分析了组团城市公交线网结构特征。研究结果表明:组团城市公交线网具有偏大的线路长度和非直线系数;公交复线条数和线路网密度在不同组团存在多个高值中心;不同剖面上线路网密度起伏显著;组团连接地带公交复线条数过大而成为通行瓶颈。这些特征增大了城市公交营运调度的难度,也给居民出行带来不便。  相似文献   

河南省农作物虚拟水含量时空分异特征     

黄会平  曹明明  宋进喜  韩宇平  陈姗姗 《地域研究与开发》2015,(3):167-171,176

在GIS技术的支持下,通过对1978—2013年河南省冬小麦、夏玉米、花生、棉花、油料作物、蔬菜6种主要农作物虚拟水量的计算与分析,探讨了其时空分异规律。河南省6种农作物单位质量虚拟水量在不断下降的趋势下有波动,2003年出现峰值,与当年大旱、所有农作物大面积减产有关;在农作物类型中,棉花单位质量虚拟水含量最高,多年平均值达到8 077.4 m3/t,蔬菜最低,多年平均值仅为159.95 m3/t。6种作物的虚拟水含量在空间分布上有明显差异,按其2013年的产量进行加权分析得到,第一等级区域为三门峡、郑州、信阳,第二等级为平顶山、洛阳、济源、开封,第三等级为南阳、驻马店、新乡、鹤壁、安阳、濮阳,第四等级为漯河,最低为许昌、周口、商丘、焦作。从整体看,西部、南部虚拟水含量高,而北部、东部虚拟水含量低。  相似文献   

一种基于事件的双序列时空数据模型     

刘飞  何珍文  郑新奇 《地理与地理信息科学》2015,31(3)

针对现有时空数据模型研究中存在的诸多不足,特别是基于事件的时空模型缺乏以空间对象个体为单位的时空变化贯穿式表达能力等缺点,提出一种基于事件的双序列时空数据模型,将状态变化与空间对象的变化用双重序列表达,用序列存储对象的变化解决了现有时空数据模型基于空间对象个体时空变化信息表达能力弱的问题。实验表明,该模型可有效用于时空数据管理。  相似文献