Groundwater vulnerability mapping: A GIS and fuzzy rule based integrated tool

Contamination of groundwater has become a major concern in recent years. Since testing of water quality of all domestic and irrigation wells within large watersheds is not economically feasible, one frequently used monitoring strategy is to develop contamination potential maps of groundwater, and then prioritize those wells located in the potentially highly contaminated areas for testing of contaminants. However, generation of contamination potential maps based on groundwater sensitivity and vulnerability is not an easy task due inherent uncertainty. Therefore, the overall goal of this research is to improve the methodology for the generation of contamination potential maps by using detailed landuse/pesticide and soil structure information in conjunction with selected parameters from the DRASTIC model. The specific objectives of this study are (i) to incorporate GIS, GPS, remote sensing and the fuzzy rule-based model to generate groundwater sensitivity maps, and (ii) compare the results of our new methodologies with the modified DRASTIC Index (DI) and field water quality data. In this study, three different models were developed (viz. DI_fuzz, VI_fuzz and VI_{fuzz_ped}) and were compared to the DI. Once the preliminary fuzzy logic-based (DI_fuzz) was generated using selected parameters from DI, the methodology was further refined through VI_fuzz and VI_{fuzz_ped} models that incorporated landuse/pesticide application and soil structure information, respectively. This study was conducted in Woodruff County of the Mississippi Delta region of Arkansas. Water quality data for 55 wells were used to evaluate the contamination potential maps. The sensitivity map generated by VI_{fuzz_ped} with soil structure showed significantly better coincidence results when compared with the field data.     

Urban development and flooding in Houston Texas, inferences from remote sensing data using neural network technique

The effects of urban development on the natural ecosystem and its link to the increased flooding in Houston, Texas were evaluated. Houston is suitable for this type of analysis due to its 1.95 million population, large geographic area and fast growth rate. Using neural network techniques, four Landsat Thematic Mapper images were grouped into five land use classes for the period 1984 to 2003: vegetation, bare ground, water, concrete and asphalt. Results show that asphalt and concrete increased 21% in the time period 1984–1994, 39% in 1994–2000 and 114%, from 2000 to 2003, while vegetation suffered an overall decrease. When change detection data are compared with runoff ratio data, a relationship between increased runoff and urban development is apparent, which indicates increased chances of flooding. Initial results of this work are made available to the public in GIS format via internet using Arc Internet Map Server (ArcIMS) at .     

夜间灯光遥感对城市发展类动能与相似性评估

评估城市发展水平与制定城市规划和城市发展政策息息相关.已有研究表明人口、国内生产总值(GDP)等统计数据和夜间灯光遥感数据能够用来衡量城市发展水平,但大多研究只关注城市发展总量,忽视了发展速度对城市发展的影响.因此,本文基于2012年—2019年Suomi NPP-VIIRS(Suomi National Polar-...     

GPS网中已知点粗差探测时限差的研究

在利用附合导线法对GPS网中已知点的可靠性进行检核时,本文对如何合理地、客观地确定限差,以达到有效检核的目的进行了探讨,提出了检核限差标准。并结合实例进行计算和分析,成功地剔除了含有粗差的已知点。     

一种全自动提取居民地的方法

对遥感影像中居民地提取的各种方法作了一般性的阐述,并在吸收这些算法优势的同时,提出了一种全自动实现遥感影像中居民地目标的提取方法：先求取非最大值抑制后的梯度图,而后进行高斯模糊处理,以提高影像上居民地区域纹理特征一致性;通过增强大津法和形态学的方法全方位腐蚀与膨胀,完成面状地物居民地的提取;最后进行图象矢量化处理。论述方法的同时,展示和分析了实验结果。     

武汉市区域似大地水准面精化成果应用分析

介绍了武汉市区域似大地水准面精化成果的应用分析、评价以及应用GPS静态和以WHCORS系统的网络RTK的两种作业方法,对两种方法所得成果进行了精度分析,并论述了两种方法的适用范围。     

GPS RTK校准检测试验场建设的研究

叙述了GPSRTK接收机校准检测试验场建设的方法,介绍了GPSRTK接收机校准检测的步骤,提出了GPSRTK校准检测的项目和结果判定方法,为未来的GPSRTK国家检定规程的出台做了有益地探索。     

基于GPS/CDMA集成的移动定位与服务技术

随着空间信息技术的发展,移动定位服务需要更高的定位精度。人们的活动范围越来越不确定,这给移动通信带来了无限商机和挑战,在此领域,日本处于世界领先地位,国内主要有Nokia、Ericsson、Motorola等。提出了一种基于GPS／CDMA集成的移动定位与服务技术,并分析了其中关键技术和实施的可行性。