基于REST和AJAX的WebGIS设计与实现

针对传统WebGIS技术存在的问题,提出REST架构风格与AJAX技术相结合的理念,设计并实现福建省交通地理信息发布系统。系统基于ArcGIS Server JavaScript API,并通过Extjs引擎实现地图的查询和统计分析等功能。结果表明基于REST与AJAX的WebGIS架构减轻了服务器端负载,增加客户端与服务器的交互能力,提高了系统的互操作性和伸缩性。     

Streambank sediment loading rates at the watershed scale and the benefit of riparian protection

Streambank erosion is a pathway for sediment and nutrient loading to streams, but insufficient data exist on the magnitude of this source. Riparian protection can significantly decrease streambank erosion in some locations, but estimates of actual sediment load reductions are limited. The objective of this research was to quantify watershed‐scale streambank erosion and estimate the benefits of riparian protection. The research focused on Spavinaw Creek within the Eucha‐Spavinaw watershed in eastern Oklahoma, where composite streambanks consist of a small cohesive topsoil layer underlain by non‐cohesive gravel. Fine sediment erosion from 2003 to 2013 was derived using aerial photography and processed in ArcMap to quantify eroded area. ArcMap was also utilized in determining the bank retreat rate at various locations in relation to the riparian vegetation buffer width. Box and whisker plots clearly showed that sites with riparian vegetation had on average three times less bank retreat than unprotected banks, statistically significant based on non‐parametric t‐tests. The total soil mass eroded from 2003 to 2013 was estimated at 7.27 × 10⁷ kg yr.^?1, and the average bank retreat was 2.5 m yr.^?1. Many current erosion models assume that fluvial erosion is the dominant stream erosion process. Bank retreat was positively correlated with stream discharge and/or stream power, but with considerable variability, suggesting that mass wasting plays an important role in streambank erosion within this watershed. Finally, watershed monitoring programs commonly characterize erosion at only a few sites and may scale results to the entire watershed. Selection of random sites and scaling to the watershed scale greatly underestimated the actual erosion and loading rates. Copyright © 2016 John Wiley & Sons, Ltd.     

新疆新源县暴雨洪涝灾害风险区划

本研究选用新疆新源县34个气象站2010-2019年日降水量、地理信息及社会经济等数据,采用归一化及GIS等方法,结合致灾因子危险性、孕灾环境敏感性和承灾体易损性,得出新源县暴雨洪涝灾害5个等级风险区划图。结果表明：新疆新源县暴雨洪涝灾害风险呈“东-北”分布的趋势,吐尔根乡、吐尔根农场、阿热勒托别镇、坎苏乡与那拉提镇属于洪涝高风险区;阿热勒托别镇、坎苏乡与那拉提镇的大部分区域及71、72团场属于次高风险区;新疆新源县中东部区域为中等风险区;其余区域为次低风险区与低风险区。     

地形图自动分幅模型的设计与实现

地形图分幅空间数据库常规构建方法对操作者要求较高,步骤烦琐,效率较低.本文基于ArcGIS Model Builder设计了一套地形图自动分幅模型,实现了自动构建适应研究区范围的多种比例尺地形图分幅空间数据库的功能.该模型可以很好地实现共享与复用,减少重复性劳动,提高数据处理效率,具有较好的推广意义.文中对模型设计流程...     

Remote sensing classification approach to large-scale crop cultivation identification: A case study of the Aral Sea Basin

Since the collapse of the Soviet Union, the crop cultivation structure in the Aral Sea Basin has changed dramatically, and these changes are worth studying. However, historical crop remote sensing mapping at the watershed scale remains challenging, especially crop misclassification at the cropland edge due to mixed pixels. Therefore, we proposed a field segmentation approach to constrain field edges based on time-series Sentinel-2 remote sensing images and the Google Earth Engine platform and then employed the random forest algorithm to perform crop classification based on time series Landsat/Sentinel-2 images and crop phenology information to produce historical crop maps in the Aral Sea Basin from the 1990s onward. The results showed that the intersection over union between the extracted field edges and in situ-measured field size data was 0.65. The overall accuracy of crop mapping was 95.2% in 2019. Then, we extended our method to historical mapping over the 1991–2015 period with accuracies ranging from 82.8% to 91.3%. Moreover, our method applied to historical mapping works well in terms of accuracy and policy matching. These findings indicate that our method can accurately distinguish cropland edges to reduce classification errors due to mixed pixels. This method is promising for solving the cropland edge problem for historical crop mapping in the Aral Sea Basin and can potentially provide a reference for historical crop classification in other watersheds of the world.     

徐州煤矿地质资料数据库建设及应用

通过对徐州煤矿地质资料的标准化整理，归纳并探讨多源数据融合的原则和标准，形成统一的空间坐标参数和数据格式，达到多源数据统一融合的目的。基于ArcGIS平台，建立涵盖基础地质、矿山开发利用、钻孔、采空区、塌陷及已治理区5大专题的煤矿地质资料数据库。项目成果纳入徐州自然资源“一张图”系统中，服务于矿政管理、矿地融合研究、工程建设新项目规划选址、国土空间规划等工作。     

基于ArcGIS的网格化雷电灾害风险评估方法研究与应用*

结合镇海区实际，开展大片区建（构）筑物网格化雷电灾害风险评估模型构建与应用，解决雷电灾害风险评估仅停留在依据灾后损失指标的单体建（构）筑物风险分布评估情况。在常规电气—几何雷电灾害风险评估模型基础上创新应用，引入地理信息处理技术将评估区域进行网格化分割，建立格点内包含建（构）筑物高度及其梯度、土壤电阻率及其梯度、直击雷防护效率、有效截收面积、地闪密度、电子电气设备系统、人口密度、火灾风险等指标在内的多层次网格化雷电灾害风险评估模型，并以辖区某化工企业厂区雷电灾害风险评估为例，对模型实践可行性应用示例。结果表明：对各指标数据集综合分析计算并运用ArcGIS风险区划，结合厂区功能布局特点分析评价，结果与市级雷电灾害风险评估报告、省级雷电易发区划基本一致。采用地理信息技术网格化处理大范围、跨区域雷电灾害风险评估方法，从“点”到“面”建立数学模型，对评估区域范围及扩展范围的雷电灾害风险评估、风险区划、政府决策支持等具有指导意义。     

长时序Landsat的北极Lena河DOC浓度变化及驱动力分析

北极Lena河是世界第十长河,也是北极地区第二大河,其年径流量约占北冰洋淡水总量的20％,同时将陆地生态系统上的大量有机物携带进海洋,并且在全球碳循环中起到非常重要的作用.卫星遥感数据是监测河流有机碳循环的重要数据源,特别是在无冰期的高纬度地区.本研究的目的是:(1)建立一种高精度反演算法估算北极Lena河的溶解有机碳...     

Google Earth Engine云平台对遥感发展的改变

近年来,随着遥感技术的快速发展,积累了海量的对地观测遥感数据.传统桌面端遥感处理平台(例如ERDAS和ENVI等)无法满足当前遥感大数据的应用需求.作为领先的遥感云计算平台,GEE (Google Earth Engine)的出现改变了传统遥感数据处理和分析模式,为海量数据快速处理与信息挖掘带来了新的契机.截止目前,科...