Update and spatial extension of strategic forest inventories using time series remote sensing and modeling     

《International Journal of Applied Earth Observation and Geoinformation》2020

Up-to-date forest inventory information relating the characteristics of managed and natural forests is fundamental to sustainable forest management and required to inform conservation of biodiversity and assess climate change impacts and mitigation opportunities. Strategic forest inventories are difficult to compile over large areas and are often quickly outdated or spatially incomplete as a function of their long production cycle. As a consequence, automated approaches supported by remotely sensed data are increasingly sought to provide exhaustive spatial coverage for a set of core attributes in a timely fashion. The objective of this study was to demonstrate the integration of current remotely-sensed data products and pre-existing jurisdictional inventory data to map four forest attributes of interest (stand age, dominant species, site index, and stem density) for a 55 Mha study region in British Columbia, Canada. First, via image segmentation, spectrally homogenous objects were derived from Landsat surface-reflectance pixel composites. Second, a suite of Landsat-based predictors (e.g., spectral indices, disturbance history, and forest structure) and ancillary variables (e.g., geographic, topographic, and climatic) were derived for these units and used to develop predictive models of target attributes. For the often difficult classification of dominant species, two modelling approaches were compared: (a) a global Random Forests model calibrated with training samples collected over the entire study area, and (b) an ensemble of local models, each calibrated with spatially constrained local samples. Accuracy assessment based upon independent validation samples revealed that the ensemble of local models was more accurate and efficient for species classification, achieving an overall accuracy of 72% for the species which dominate 80% of the forested areas in the province. Results indicated that site index had the highest agreement between predicted and reference (R² = 0.74, %RMSE = 23.1%), followed by stand age (R² = 0.62, %RMSE = 35.6%), and stem density (R² = 0.33, %RMSE = 65.2%). Inventory attributes mapped at the image-derived unit level captured much finer details than traditional polygon-based inventory, yet can be readily reassembled into these larger units for strategic forest planning purposes. Based upon this work, we conclude that in a multi-source forest monitoring program, spatially localized and detailed characterizations enabled by time series of Landsat observations in conjunction with ancillary data can be used to support strategic inventory activities over large areas.  相似文献   

Discussion on establishing monitoring networks for temperature fields of shallow thermal energy in Shandong,China          下载免费PDF全文

ZHOU Bo  WEI Shan-ming  WANG Tao  NIE Yu-peng  WANG Chuan-qi 《地下水科学与工程》2019,7(1):86-93

In the recent decade, the construction projects related to shallow geothermal energy engineering have undergone rapid development in Shandong Province. The predominant type of these developments and applications was heat exchange through buried tubes and the main targets were residential and office buildings. However, an overwhelming majority of the completed geothermal heat pump projects lacked monitoring devices so that they were unable to comprehensively reflect the background values for the geothermal fields within the province and few researches were conducted on their influence on the geological environment. In this paper, locations for monitoring shallow geothermal energy and their validity of the monitoring point deployment were studied in view of the development and application status as well as geological background conditions of various projects located in multiple cities providing data support for analyzing the fluctuation trend and influence of large-scale shallow geothermal energy applications on the shallow geothermal and the feasibility and parameter designs of newly built systems in Shandong Province in the future.  相似文献   

Main progress and prospect for China's hydrogeological survey          下载免费PDF全文

WU Ai-min  HAO Ai-bing  GUO Hai-peng  LIU Jing-tao  ZHANG Er-yong  WANG Huang  WANG Xin-feng  WEN Xue-ru  ZHANG Cui-guang 《地下水科学与工程》2020,8(3):195-209

This paper reviewed the main achievements of hydrogeological survey in China, summarized the significant progress of hydrogeological survey over the past decade, and forecasted the key responsibilities for hydrogeological survey in the p14th Five-year Planq. The significant progress includes: China established the 1: 50 000 standard hydrogeological survey system with Chinese characteristics and produced the new generation of high-quality hydrogeological maps; the national groundwater monitoring project was completed and accepted, which marks China taking the leading position in groundwater monitoring internationally; fruitful results were achieved in the national groundwater quality survey, and groundwater quality background values were basically identified and checked; hydrogeological and environmental geological survey was continuously promoted in karst areas and the ecological restoration of rocky desertification achieved remarkable results; China strengthened layer exploration techniques for groundwater, integrating the key and practical techniques of layer exploration and monitoring; the exploration of groundwater in the poverty-stricken regions and old revolutionary base areas were effectively promoted to strongly guarantee the poverty alleviation and drinking water safety; the mystery of desert groundwater was uncovered, making up for the shortage of 1: 250 000 hydrogeological survey in the Badain Jaran Desert; and more efforts were made to conduct survey on the water resources in the basin, and to finish the unified measurement of national-scale groundwater level.  相似文献   

Estimation of groundwater storage from seismic data using deep learning     

Timo Lähivaara  Alireza Malehmir  Antti Pasanen  Leo Kärkkäinen  Janne M.J. Huttunen  Jan S. Hesthaven 《Geophysical Prospecting》2019,67(8):2115-2126

Convolutional neural networks can provide a potential framework to characterize groundwater storage from seismic data. Estimation of key components, such as the amount of groundwater stored in an aquifer and delineate water table level, from active-source seismic data are performed in this study. The data to train, validate and test the neural networks are obtained by solving wave propagation in a coupled poroviscoelastic–elastic media. A discontinuous Galerkin method is applied to model wave propagation, whereas a deep convolutional neural network is used for the parameter estimation problem. In the numerical experiment, the primary unknowns estimated are the amount of stored groundwater and water table level, while the remaining parameters, assumed to be of less of interest, are marginalized in the convolutional neural network-based solution. Results, obtained through synthetic data, illustrate the potential of deep learning methods to extract additional aquifer information from seismic data, which otherwise would be impossible based on a set of reflection seismic sections or velocity tomograms.  相似文献   

Intra-survey reservoir fluctuations – implications for quantitative 4D seismic analysis     

Veronica Omofoma  Colin MacBeth  Hamed Amini 《Geophysical Prospecting》2019,67(2):282-297

During the time taken for seismic data to be acquired, reservoir pressure may fluctuate as a consequence of field production and operational procedures and fluid fronts may move significantly. These variations prevent accurate quantitative measurement of the reservoir change using 4D seismic data. Modelling studies on the Norne field simulation model using acquisition data from ocean-bottom seismometer and towed streamer systems indicate that the pre-stack intra-survey reservoir fluctuations are important and cannot be neglected. Similarly, the time-lapse seismic image in the post-stack domain does not represent a difference between two states of the reservoir at a unique base and monitor time, but is a mixed version of reality that depends on the sequence and timing of seismic shooting. The outcome is a lack of accuracy in the measurement of reservoir changes using the resulting processed and stacked 4D seismic data. Even for perfect spatial repeatability between surveys, a spatially variant noise floor is still anticipated to remain. For our particular North Sea acquisition data, we find that towed streamer data are more affected than the ocean-bottom seismometer data. We think that this may be typical for towed streamers due to their restricted aperture compared to ocean-bottom seismometer acquisitions, even for a favourable time sequence of shooting and spatial repeatability. Importantly, the pressure signals on the near and far offset stacks commonly used in quantitative 4D seismic inversion are found to be inconsistent due to the acquisition timestamp. Saturation changes at the boundaries of fluid fronts appear to show a similar inconsistency across sub-stacks. We recommend that 4D data are shot in a consistent manner to optimize aerial time coverage, and that additionally, the timestamp of the acquisition should be used to optimize pre-stack quantitative reservoir analysis.  相似文献   

陕西测震台网地震速报结果评估     

王平  狄秀玲  关昕  古云鹤  赵韬 《内陆地震》2014,(1):57-62

陕西省"十五"数字测震台网的建成并投入运行,极大地提高了陕西测震台网地震监测能力和地震速报能力,并成功地经受了四川汶川8.0级地震的考验。在2008年5月12日14时28分汶川8.0级地震后至5月31日,陕西测震台网速报地震669个,其中在地震速报规定范围内速报5级以上地震11个。在应对2009年11月5日陕西高陵4.4级地震(Ⅰ类速报地震)和2013年7月22日甘肃岷县6.6级地震(Ⅲ类速报地震)及余震序列时,两个主震各种速报参数偏差全部符合地震速报规定对相应类别地震速报的要求。  相似文献   

环渤海虚拟台网的运行管理   总被引：1，自引：0，他引：1  

许可  刘瑞瑞  孔繁旭  薛娜  高文晶 《华北地震科学》2014,(3):55-60

针对天津市＂十一五＂期间的建设成果环渤海虚拟台网,从系统部署、运行监控、信息发布、系统维护等方面介绍了虚拟台网技术在天津地区的应用情况,并利用JAVA图像裁切技术解决了环渤海虚拟台网对天津地区速报地震的乡镇级震中位置显示问题。该台网的建成,不仅提高了天津台网对渤海海域的地震监测能力和研究水平,同时也为天津市各区县地办完善监测预报体系、提升社会显示度,提供了良好的机遇。  相似文献   

Spatial–temporal variability in water quality and macro-invertebrate assemblages in the Upper Mara River basin,Kenya     

《Physics and Chemistry of the Earth》2014

Tropical rivers display profound temporal and spatial heterogeneity in terms of environmental conditions. This aspect needs to be considered when designing a monitoring program for water quality in rivers. Therefore, the physico-chemical composition and the nutrient loading of the Upper Mara River and its two main tributaries, the Amala and Nyangores were monitored. Initial daily, and later a weekly monitoring schedule for 4 months spanning through the wet and dry seasons was adopted. Benthic macro-invertebrates were also collected during the initial sampling to be used as indicators of water quality. The aim of the current study was to investigate the physico-chemical status and biological integrity of the Upper Mara River basin. This was achieved by examining trends in nutrient concentrations and analyzing the structure, diversity and abundance of benthic macro-invertebrates in relation to varying land use patterns. Sampling sites were selected based on catchment land use and the level of human disturbance, and using historical records of previous water quality studies. River water pH, dissolved oxygen, electrical conductivity (EC), temperature, and turbidity were determined in situ. All investigated parameters except iron and manganese had concentration values within allowable limits according to Kenyan and international standards for drinking water. The Amala tributary is more mineralized and also shows higher levels of pH and EC than water from the Nyangores tributary. The latter, however, has a higher variability in both the total phosphorus (TP) and total nitrogen (TN) concentrations. The variability in TP and TN concentrations increases downstream for both tributaries and is more pronounced for TN than for TP. Macro-invertebrate assemblages responded to the changes in land use and water quality in terms of community composition and diversity. The study recommends detailed continuous monitoring of the water quality at shorter time intervals and to identify key macro-invertebrate taxa that can be used to monitor changes of the water quality in rivers of the Mara basin as a result of anthropogenic changes.  相似文献   

极地环境监测网的设计及其在南极普里兹湾的应用     

程文芳  朱建钢  吴荣荣  詹德川  陆大海  闫可  郑小罗 《海洋科学》2018,42(2):34-45

为了保护南极和北极的生态系统和环境,中国自20世纪90年代初开始推行和实施了极地环境监测计划,部署了各学科监测传感器阵列;采集了多学科数据,包括海洋、大气、冰冻圈、生物圈等主题;架构了"R/V雪龙号破冰船—极地考察站—国内基地"之间的快速数据传输网络;建立了海洋环境监测系统、太阳能地面空间监测系统、生态环境监测系统等系列监测系统。为了实现长期监测,达到预测和预警目标,本文针对国内外现状,在现有基础上设计了一套中国极地环境长期监测网(Polar Environment monitoring network of China,CPEMN)。该监测网集成各监测系统并在监测指标设计上覆盖我国极地所有常规监测/观测任务,且根据国际科研动态和长期监测规划拓展了预期监测范围。最后本文利用南极普里兹湾进行的破冰导航应用示范验证了CPEMN具有可执行性。  相似文献   

地理国情监测水面数据时空一致性优化方法     

程滔  周旭  郑新燕  郭建坤  袁如金 《地球信息科学学报》2018,20(9):1216-1224

地理国情监测利用遥感、地理信息等技术,动态获取地表覆盖等多样化的地理要素,经统计、分析、评价和应用,服务于政治、经济、文化、资源、环境等多个领域,为政府提供全面、准确、基础的地理信息情报。针对地理国情监测在全国范围基于多时相遥感影像采集水面信息存在时空不一致性的现状,提出一种基于精细DEM的水面数据时空一致性优化方法。利用栅格图形区域生长算法,采用8邻域算子,对水面种子点进行迭代生长计算,得出基于精细DEM的区域生长结果;通过与地理国情监测水面数据对比分析,实现空间化结果的修正,从而达到时空一致性优化的目的。分析了典型研究区水面数据特征,利用该方法进行了优化处理,结果显示：研究区水面数据空间范围相对于时点监测修正了7.99%,满足了地理国情监测时点一致性需求。研究表明：该方法的应用,能够使得在全国尺度上统计的水面数据反映同一季节或可接受时段内的状况,避免或缩小了由于影像数据源的差异造成的时间和空间上的不一致性带来的误差,满足了地理国情监测时点一致性需求,能够在地理国情监测等地表覆盖水面信息提取、优化中推广应用,为政府有效决策提供客观、准确和基础的水面信息。  相似文献