Influence of vegetation canopies on solar potential in urban environments     

《Applied geography (Sevenoaks, England)》2016

Solar energy is clearly a promising option among the many available sources of renewable energy, and its market has seen outstanding growth. Careful evaluation to determine suitable locations for photovoltaic installations is needed, however, as their efficiency is highly dependent on exposure to sun. Especially in urban environments, quantifying the shadows cast by other buildings and vegetation canopies may be essential. In the present study, we used light detection and ranging (LiDAR) data and geographic information systems (GIS) to assess the influence of shading vegetation on solar irradiation estimates in five European towns. The fraction of annual solar irradiation lost to shading by existing vegetation ranged between 3% and 11%. The fraction lost was higher in winter and lower in summer. Due to greater incoming solar radiation in summer, however, more than 50% of annual loss was accounted for in summer. We suggest that at the broad scale of whole cities the influence of vegetation on rooftop solar potential estimates is negligible (especially in densely populated areas). Analyses which do not consider vegetation because of data availability nevertheless provide valuable insight into localities' solar potential.  相似文献   

航空电磁法在黄河口地区寻找浅层淡水的地质效果   总被引：1，自引：0，他引：1  

王卫平  王越胜 《物探与化探》1999,23(2):115-121,127

对利用航空电磁法寻找浅层淡水的方法技术进行了探索,根据找水需要编制了保留区域场的三频标差异常图,对本区的海侵界线及海侵程度进行了研究,并在咸水区内圈定浅层淡水远景区29处,对各淡水远景区进行了分析与评价.  相似文献   

北部湾北海─临高海区的空气微生物     

陈皓文 《热带海洋学报》1999,(3)

对北部湾的北海-临高海区作了空气微生物含量考察。结果表明,测区的空气平均细菌、真菌、总菌量及真菌/总菌的百分比分别为632．3,1324．0,1956．3CFU·m-3及67．7％。数据分析显示：测区空气微生物含量呈北高、南低、中间最少的势态;近岸海区的比相邻陆区的低,海上部分的平均比环海南岛上空的稍大,比粤西海区的稍少。其昼夜变化显示出空气细菌量峰值出现在晨间,谷值在中午。真菌量的峰值出现在黄昏,谷值在上午。其状态基本上不同于北海市区的,但近似于相邻海区的。空气做生物含量与气温间无显著相关关系。结果意味着空气污染近岸区重于海上区,人为活动的影响也较海上区的大。  相似文献   

APPLICATION OF UAVLS TO RAPID GEOLOGICAL SURVEYS          下载免费PDF全文

SHAO Yan-xiu  ZHANG Bo  ZOU Xiao-bo  WANG Ai-guo  ZHANG Fan-yu  YUAN Dao-yang  LIU Xing-wang  HE Wen-gui 《地震地质》2017,39(6):1185-1197

Three-dimensional scanning with LiDAR has been widely used in geological surveys. The LiDAR with high accuracy is promoting geoscience quantification. And it will be much more convenient, efficient and useful when combining it with the Unmanned Aerial Vehicle (UAV). This study focuses on UAV-based Laser Scanning (UAVLS)geological field mapping, taking two examples to present advantages of the UAVLS in contrast with other mapping methods. For its usage in active fault mapping, we scanned the Nanpo village site on the Zhangxian segment of the West Qinling north-edge fault. It effectively removed the effects of buildings and vegetation, and uncovered the fault trace. We measured vertical offset of 1.3m on the terrace T₁ at the Zhang river. Moreover, we also scanned landslide features at the geological hazard observatory of Lanzhou University in the loess area. The scanning data can help understand how micro-topography affects activation of loess landslides. The UAVLS is time saving in the field, only spending about half an hour to scan each site. The amount of average points per meter is about 600, which can offer topography data with resolution of centimeter. The results of this study show that the UAVLS is expected to become a common, efficient and economic mapping tool.  相似文献   

Controls on the occurrence and prevalence of floodplain channels in meandering rivers          下载免费PDF全文

Scott R. David  Douglas A. Edmonds  Sally L. Letsinger 《地球表面变化过程与地形》2017,42(3):460-472

The process of channelization on river floodplains plays an essential role in regulating river sinuosity and creating river avulsions. Most channelization occurs within the channel belt (e.g. chute channels), but growing evidence suggests some channels originate outside of the channel‐belt in the floodplain. To understand the occurrence and prevalence of these floodplain channels we mapped 3064 km² of floodplain in Indiana, USA using 1.5 m resolution digital elevation models (DEMs) derived from airborne light detection and ranging (LiDAR) data. We find the following range of channelization types on floodplains in Indiana: 6.8% of floodplain area has no evidence of channelization, 55.9% of floodplains show evidence (e.g. oxbow lakes) of chute‐channel activity in the channel belt, and 37.3% of floodplains contain floodplain channels that form long, coherent down‐valley pathways with bifurcations and confluences, and they are active only during overbank discharge. Whereas the first two types of floodplains are relatively well studied, only a few studies have recognized the existence of floodplain channels. To understand why floodplain channels occur, we compared the presence of channelization types with measured floodplain width, floodplain slope, river width, river meander rate, sinuosity, flooding frequency, soil composition, and land cover. Results show floodplain channels occur when the fluvial systems are characterized by large floodplain‐to‐river widths, relatively higher meandering rates, and are dominantly used for agriculture. More detailed reach‐scale mapping reveals that up to 75% of channel reaches within floodplain channels are likely paleo‐meander cutoffs. The meander cutoffs are connected by secondary channels to form floodplain channels. We suggest that secondary channels within floodplains form by differential erosion across the floodplain, linking together pre‐existing topographic lows, such as meander cutoffs. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Modelling soil moisture in a high‐latitude landscape using LiDAR and soil data          下载免费PDF全文

Julia Kemppinen  Pekka Niittynen  Henri Riihimäki  Miska Luoto 《地球表面变化过程与地形》2018,43(5):1019-1031

Soil moisture has a pronounced effect on earth surface processes. Global soil moisture is strongly driven by climate, whereas at finer scales, the role of non‐climatic drivers becomes more important. We provide insights into the significance of soil and land surface properties in landscape‐scale soil moisture variation by utilizing high‐resolution light detection and ranging (LiDAR) data and extensive field investigations. The data consist of 1200 study plots located in a high‐latitude landscape of mountain tundra in north‐western Finland. We measured the plots three times during growing season 2016 with a hand‐held time‐domain reflectometry sensor. To model soil moisture and its temporal variation, we used four statistical modelling methods: generalized linear models, generalized additive models, boosted regression trees, and random forests. The model fit of the soil moisture models were R² = 0.60 and root mean square error (RMSE) 8.04 VWC% on average, while the temporal variation models showed a lower fit of R² = 0.25 and RMSE 13.11 CV%. The predictive performances for the former were R² = 0.47 and RMSE 9.34 VWC%, and for the latter R² = 0.01 and RMSE 15.29 CV%. Results were similar across the modelling methods, demonstrating a consistent pattern. Soil moisture and its temporal variation showed strong heterogeneity over short distances; therefore, soil moisture modelling benefits from high‐resolution predictors, such as LiDAR based variables. In the soil moisture models, the strongest predictor was SAGA (System for Automated Geoscientific Analyses) wetness index (SWI), based on a 1 m² digital terrain model derived from LiDAR data, which outperformed soil predictors. Thus, our study supports the use of LiDAR based SWI in explaining fine‐scale soil moisture variation. In the temporal variation models, the strongest predictor was the field‐quantified organic layer depth variable. Our results show that spatial soil moisture predictions can be based on soil and land surface properties, yet the temporal models require further investigation. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

基于广义模型约束的时间域航空电磁反演研究   总被引：1，自引：0，他引：1       下载免费PDF全文

苏扬  殷长春  刘云鹤  张博  任秀艳 《地球物理学报》2019,62(2):743-751

由于航空电磁具有海量数据,因此快速有效的成像和反演手段至关重要.本文针对层状介质模型推导与实现了广义模型约束条件下时间域航空电磁一维反演.从正则化反演的目标函数出发,通过改变模型约束项构造Lp范数反演和聚焦反演,进而通过改变模型求解域构造出基于小波变换的稀疏约束反演.针对不同反演方法目标函数的构建方式,本文进一步从数学原理上分析不同反演方法的预期效果,并通过理论模型和实测数据进行验证.结果表明L0.8范数反演、聚焦反演和基于小波变换的稀疏约束反演可以得到更符合地下层状介质陡变界面的反演结果.  相似文献   

黄土高原中东部沙尘与非沙尘天气花粉组成及来源范围     

李月从  许清海  葛亚汶  李英  吕素青  曹现勇  田芳  郝利生 《地理研究》2014,33(12):2367-2381

通过黄土高原两个不同地区(浑源、洛川)沙尘与非沙尘天气花粉组合的对比来探讨主要花粉类型最大传播距离。结果表明：沙尘天气花粉汇集量明显高于非沙尘天气,特别是蒿属和藜科花粉,沙尘天气平均是非沙尘天气的3倍以上。随风速增大,花粉可能的最大源区范围明显增大。风速低于3.3 m/s时,蒿属和藜科花粉多来自100 km范围内,其他类型花粉来源范围不超过20 km;风速大于5.9 m/s时,蒿属和藜科花粉源区范围增至300 km以上;其他类型花粉不超过100 km。风速达到12.5 m/s时,蒿属及藜科最大花粉源区范围可达1000 km,其他类型花粉不超过300 km。浑源地区不论平均风速还是最大风速均明显高于洛川地区,因此,主要花粉类型可能的最大源区范围达200 km,大于洛川地区(低于100 km)。  相似文献   

自适应移动盒子的机载LiDAR点云去噪算法     

李炼  王蕾  刘刚  郭加伟 《测绘科学》2016,41(4):144-147

针对现有LiDAR点云去噪算法难以实现自适应的问题,该文提出了基于空间盒子结构的自适应移动盒子去噪算法。基于经验模型建立盒子自适应准则,较好规避了现有算法的去噪阈值确定问题;采用聚类分析实现噪声点与有效点的精确标示。基于不同类型噪声的点云数据实验结果表明:与现有去噪算法相比,基于自适应移动盒子的去噪算法具有更好的适应性和去噪效果。  相似文献   

辽东半岛五龙金矿床航空电磁场特征及找矿意义     

石连成  骆燕  江民忠  王志宏  朱琳  陈伟  韩鹏辉  陈志鹏 《地质学报》2020,94(10):3106-3119

五龙金矿床位于五龙矿集区中部,是矿集区内规模大的石英脉型金矿。为查明矿集区深部构造及指导深部找矿预测,需结合深部地球物理资料综合分析研究。本文基于五龙矿集区航空探测任务,并结合其成矿地质特征,研究了五龙金矿在平面、剖面、空间等维度的航磁、航空TEM、航空大地电磁特征及其找矿意义。研究表明：平面上矿体位于鸡心沟断裂东侧负磁背景场中NE与近SN、NW向弱磁异常带交汇处,中等 强剩余磁异常带的转折端、梯度带,视电阻率低阻区及中低阻梯度带,深部存在团块状视磁化率高值区;剖面上矿体位于“左低右高,上高下低”的视电阻率梯度带上,呈中低阻、低阻特征及强磁场区至弱磁场区的视磁化率梯度带上,呈浅部“上高下低”、深部“下高上低”的中等 弱磁特征;空间上矿体位于鸡心沟断裂东侧的断裂构造低阻带与岩体高阻异常带的梯度带。五龙金矿地质地球物理找矿标志的建立和深部高视磁化率异常区的存在,表明矿区深部1000~2000m空间与五龙金矿体视电阻率、视磁化率特征相似的地段,仍具有较好找矿潜力。  相似文献