Geo-questionnaires in urban planning: recruitment methods,participant engagement,and data quality

ABSTRACT

Recent focus on sustainable urban development and livability has increased the demand for new data sourcing techniques to capture experiences and preferences of urban dwellers. At the same time, developments of geospatial technologies and social media have enabled new types of user-generated geographic information and spatially explicit online communication. As a result, new public participation GIS methods for engaging large groups of individuals have emerged. One such method is geo-questionnaire, an online questionnaire with mapping capabilities, which has been used to elicit geographic data in variety of topics and geographical contexts. This article presents two recent cases, in which geo-questionnaires have been used in Polish cities to obtain public input on quality of life and development preferences in local land use planning. The article evaluates participant recruitment methods focusing on sample representativeness, participant engagement, and data quality. Recruitment via social media was found to increase bias towards younger population. Paper questionnaires used along the online version provided for better representation of target population’s age structure, but did not reduce bias related to educational attainment. We discuss how these issues relate to data usability and generalizability in the context of digital divide, and suggest directions for future research.     

城市化进程对气象探测环境代表性的影响：以寿县国家气候观象台为例

为了探讨城市化进程对寿县国家气候观象台探测环境及气象要素的影响程度,本文利用高分辨陆地卫星影像结合GIS技术揭示了近25年(1987—2012)寿县县城的城市化进程及其对气象观测场周边土地利用/覆盖变化以及热环境的影响过程;以搬迁后新址为参考站,进一步分析了城市扩张对气温和风的影响。结果表明:1城市化进程中的土地利用改变是破坏寿县观象台探测环境代表性主要原因;2城建用地是影响和构成寿县旧址周围缓冲区较高地表温度的热环境分布主体,而植被和水体是较低地表温度的热环境分布主体;3城市化扩张造成旧址年平均气温偏高和年平均风速偏小,由于城市化的影响,寿县新旧站址风向的相符率仅为15%左右,且城市扩张对气象要素的影响呈现明显的日变化和季节变化特征。控制台站周边城建用地的规模和布局是改善台站热环境以及提高台站观测区域代表性的重要举措。     

黑河遥感试验中尺度上推研究的进展与前瞻

尺度问题是遥感科学研究的一个关键科学问题,但其理论和方法的发展严重受限于稀缺的多尺度观测数据。黑河生态水文遥感试验(Hi WATER)的核心目标之一是开展多尺度观测以支持尺度转换研究。本文综述了Hi WATER中定点观测的尺度上推研究进展,内容包括:(1)尝试严格定义了空间平均、空间尺度上推、观测足迹、代表性误差、观测真值等概念;(2)介绍了Hi WATER获取的多尺度(单点—像元—区域—流域)生态水文观测数据;(3)发展了基于地统计理论的多尺度采样方法,改进了基于时间稳定性的采样方法;(4)定量评估了辐射、碳通量、土壤水分、地表温度单点观测的代表性误差,实证了异质性地表遥感产品真实性检验的不确定性主要来源于观测的时空代表性;(5)发展了定点观测的尺度上推方法,将克里格方法推广至回归克里格、面到面、不等精度观测等情形,发展了贝叶斯框架下的非线性尺度上推方法,实证了引入遥感观测作为协同信息可显著提高尺度上推的精度。总之,Hi WATER初步形成了从采样设计、多尺度观测、代表性误差的度量、尺度上推新方法到真实性检验的研究框架。     

浅谈我国某金红石矿采样设计

选矿试验采样设计是一项复杂而又重要的工作,确保试样的代表性是采样设计工作的关键。本文以我国某金红石矿为例,根据矿床地质特征和矿石的性质,综合考虑影响矿石代表性的各种因素,对其进行了采样设计,以确保能够采出满足试验要求、且具有带表性的试验样品。对类似项目具有一定的指导和借鉴意义。     

Temporal and Spatial Representativeness of Alpine Sediment Yields: Cascade Mountains,British Columbia

New alpine, lake-based sediment yield data are presented from a cirque basin in the alpine zone of the Cascade Mountains, British Columbia. Average rates of sediment deposition in Glacier Lake from a 1·33 km² basin where 7 ta⁻¹(BP ) 10 300–6845 BP , 8 ta⁻¹(BP ) 6845–3390 BP and 9·8 ta ⁻¹(BP ) 3390 BP to the present. The potential representativeness of the site is carefully assessed on the basis of three major axes of variability: lithology, climate and relief. Slope frequency data suggest the site is representative of the cirque component of the landscape but not of the whole alpine zone. The results emphasize the importance of considering the spatial variability of relief and the temporal variability of climate in assessing the representativeness of sediment yield data. © 1997 by John Wiley & Sons, Ltd.     

北京降水特征及北京市观象台降水资料代表性

将北京分为城区、郊区、南部山区及北部山区4个区域,利用14个观测站1978—2010年共33年的月降水量资料,分析了不同区域降水年变化和夏季降水特征及其差异。结果表明:各区域年平均降水量存在较大差异,郊区降水量最多 (620 mm),城区与南部山区降水量较少,而北部山区降水量最少 (476 mm);城区与南部山区的年降水量较接近,二者与郊区和北部山区都有显著差异。4个区域的降水量都表现出减少趋势,郊区最明显 (47 mm/10 a),北部山区的减少趋势最小 (0.7 mm/10 a)。对4个区域夏季 (6—9月) 降水量分析发现,城区与南部山区具有较好的一致性,二者与郊区和北部山区具有显著差异。均方根偏差和相关系数的计算结果表明:北京市观象台与城区和南部山区的降水年变化和夏季降水特征差异均不显著,而与郊区和北部山区有显著差异,说明北京市观象台降水资料对城区和南部山区具有最优代表性,而对北部山区和郊区的代表性较差。     

整合已有土壤样点的数字土壤制图补样方案

我国多数地区经过两次土壤普查以及科研工作者的野外调查, 积累了一定数量的土壤样点“( 已有样点”)。本文在充分整合已有样点的基础上, 提出了逐次、高效地设计补充样点的方案, 它包括3 个步骤:首先, 确定已有样点集的空间代表范围“( 可推测范围”);然后, 将已有样点集不能代表范围内的每一个栅格都看作一个候选样点, 计算每一个候选样点的可扩推范围, 选择可扩推范围最大的点作为第一个补充样点;最后, 基于已有样点和补充样点更新样点集的空间代表范围图。重复以上过程, 直至新样点集的空间代表范围能够覆盖整个研究区。该方法在充分利用已有样点资源的基础上, 不仅能够确定补充样点的数量、位置, 而且能够给定补充样点的重要性次序, 在采样资源有限的情况下, 为采样者合理地选择样点提供了重要依据。     

基于地面资料集合均方根滤波同化方案的京津冀暴雨模拟研究

为了更加有效地同化地面自动气象站观测资料,针对模式地形与观测站地形存在的高度差异对同化效果的影响,提出了相应的解决方案。在同化系统的位温和露点观测误差中分别引入位温和露点地形代表性误差,在WRF模式中应用集合均方根滤波方法（EnSRF）同化地面自动气象站观测资料,并对2016年一次京津冀暴雨个例进行数值试验。研究结果表明,同化地面资料后,同化阶段的均方根误差、预报阶段的降水TS评分和前13个时次各要素预报均有整体改进。在观测误差中引入地形代表性误差与引入前相比,风场均方根误差得到整体改进;位温和露点的均方根误差在前期表现并不稳定,在后期有所改进;预报阶段前24 h累计降水与后24 h累计降水TS评分在整体上均有所提高。新方案能够减少高度差异对同化效果的影响。      

Are flat‐field snow depth measurements representative? A comparison of selected index sites with areal snow depth measurements at the small catchment scale

Single or a limited number of point observations, such as from index stations, are commonly assumed to be representative for the snow cover of larger areas in many applications. This study presents a systematic investigation of the relationship between point observations and areal mean snow depths ranging from the scale of tens of metres to entire catchments. We analyse aerial snow depth information from four mountain regions in the European Alps, one in the Spanish Pyrenees and one in the Canadian Rocky Mountains, obtained from airborne laser scanning surveys. This rich data set allowed to compare point values with snow cover statistics, reflecting the real snow depth distribution of the investigation areas. We present two contrasting approaches in order to assess the representativeness of typical flat‐field snow depth measurements. In the first approach, we define potential index stations based on topographic characteristics as commonly applied for snow cover monitoring stations. The point observations of these index stations are then compared with the mean values in their vicinities. We show that most of the index stations strongly overestimate the snow depth of the catchment and of their surrounding area at distances of several hundreds of metres. Results confirm the expectation that the larger the support area, the smaller the difference to the mean of the complete catchment. The second approach was to analyse topographic characteristics of all cells with snow depths that deviated less than 10% from the catchment mean. It appears that these representative cells are rather randomly distributed and cannot be identified a priori. In summary, our results show large potential biases of index stations with respect to snow distribution and therefore also snow water equivalent. Copyright © 2014 John Wiley & Sons, Ltd.