A multi-scale study on land use and land cover quality change: The case of the Yellow River Delta in China   总被引：5，自引：0，他引：5  

Xuegong Xu  Honghai Guo  Xiaoling Chen  Huiping Lin  Qiaoling Du 《GeoJournal》2002,56(3):177-183

This paper presents a case study of the Yellow River Delta in China, to trace land use and land cover changes during the past 20 years, with an emphasis on land quality changes. Three sets of data are used in this case study: remote sensing data derived from satellite images; crop yield data from statistics; and soil data collected by the researchers in the field. Our study reveals that at the regional scale, LUCC has taken place in a positive direction: vegetation cover has been expanding and crop yields per hectare have been on rise. However, while the overall eco-environment has improved, the improvement is uneven across the Delta region. At local levels, some areas show signs of increased salinization and declining organic content. Both natural forces and human activities are responsible for the LUCC, but human activities play a more important role. While some impacts of human activities are positive, the damages are often long-lasting and irreversible. We also conclude that it is necessary to use both macro data (such as remote sensing data) and micro data (data collected in the field) to study land quality change. The former are efficient in examining land quality changes at the regional scale, the latter can serve to verify ground patterns revealed from macro data and help to identify local variations, so as to get a comprehensive understanding of LUCC and promote sustainable land use and land management. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Evaluation of the Reduction in Uncertainty Obtained by Conditioning a 3D Stochastic Channel to Multiwell Pressure Data     

Fengjun Zhang  Albert C. Reynolds  Dean S. Oliver 《Mathematical Geology》2002,34(6):715-742

A stochastic channel embedded in a background facies is conditioned to data observed at wells. The background facies is a fixed rectangular box. The model parameters consist of geometric parameters that describe the shape, size, and location of the channel, and permeability and porosity in the channel and nonchannel facies. We extend methodology previously developed to condition a stochastic channel to well-test pressure data, and well observations of the channel thickness and the depth of the top of the channel. The main objective of this work is to characterize the reduction in uncertainty in channel model parameters and predicted reservoir performance that can be achieved by conditioning to well-test pressure data at one or more wells. Multiple conditional realizations of the geometric parameters and rock properties are generated to evaluate the uncertainty in model parameters. The ensemble of predictions of reservoir performance generated from the suite of realizations provides a Monte Carlo estimate of the uncertainty in future performance predictions. In addition, we provide some insight on how prior variances, data measurement errors, and sensitivity coefficients interact to determine the reduction in model parameters obtained by conditioning to pressure data and examine the value of active and observation well data in resolving model parameters.  相似文献   

G-Probe-1 - An International Proficiency Test for Microprobe Laboratories - Report on Round 1 : February 2002 (TB-1 Basaltic Glass)     

Philip J. Potts  Michael Thompson  Stephen Wilson 《Geostandards and Geoanalytical Research》2002,26(2):197-235

Results are presented for round one of a new international proficiency testing programme designed for microprobe laboratories involved in the routine analysis of silicate minerals. The sample used for this round was TB-1, a basaltic glass fused and prepared by the USGS. Thirty nine laboratories contributed data to this round, the majority of major element results being undertaken by EPMA and the majority of trace elements by LA-ICP-MS. Assigned values were derived from the median of results produced by nine selected laboratories that analysed powdered material by conventional ICP-MS, INAA and XRF techniques using bulk powders of the sample. Submitted microprobe results were evaluated using a target precision calculated using the Horwitz function, adopting the same criteria as those used for "applied" geochemistry laboratories in the companion GeoPT proficiency testing programme for laboratories involved in the routine bulk analysis of silicate rocks. An evaluation of results from participating microprobe laboratories indicated that overall, data were compatible with this precision function. A comparison between the performance of bulk and microprobe techniques used in the analysis of the basaltic glass showed remarkably good agreement, with significant bias only observed for the major oxide MgO.  相似文献   

Seismic evaluation of existing nuclear facility using ambient vibration test to characterize dynamic behavior of the structure and microtremor measurements to characterize the soil: a case study   总被引：1，自引：0，他引：1  

Ph. Volant  N. Orbovic  F. Dunand 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1159-1167

The methods used for a building seismic hazard evaluation are presented with the associated results. The goals of the study are (1) to check the soil nature and the existence or not of a possible site effect around the installation and (2) to characterize the dynamic behavior of the building using ambient vibration records.

The results of the soil study with the Nakamura method are very difficult to interpret because they are not stable in space and time. The spectral ratios method has been used with regional earthquake records. The results of the application of this method allowed us to conclude that the installation was free of site effect.

The ambient vibration measurements on the building brought the conclusion to determine the first and second modes of the structure. These results have been used to calibrate numerical model. The modal shapes in plan (high roof) and in elevation (main column) have been evaluated. The damping of the building has been computed using ambient vibration records.  相似文献   

Fish zonation in a Mediterranean stream: Effects of human disturbances   总被引：7，自引：0，他引：7  

Anna Vila-Gispert  Emili García-Berthou  Ramon Moreno-Amich 《Aquatic Sciences - Research Across Boundaries》2002,64(2):163-170

  相似文献   

An scientific evaluation of annual earthquake prediction ability   总被引：1，自引：0，他引：1  

张国民  刘杰  石耀霖 《地震学报(英文版)》2002,15(5):550-558

Introduction There have been nearly 40 years for earthquake prediction since the research on earthquake prediction was carried out in plan by some advanced countries since 1960s. For the hard long process of earthquake prediction, Alen, American famous scientist and former president of the evaluation commission of earthquake prediction in California, USA, said that the difficulty of earthquake prediction is more than the expected and the practical progress of earthquake prediction is more sl…  相似文献   

金沙江干热河谷土地荒漠化评价方法研究   总被引：7，自引：5，他引：7  

范建容  刘淑珍  钟祥浩  李勇 《地理科学》2002,22(2):243-248

什么样的退化土地才是荒漠化土地，土地荒漠化的发生发展以及程度和区别等问题的定量确定，至今有关报道甚少。干热河谷是我国西南地区特殊的生态环境类型，自然资源丰富，但土地荒漠化问题十分突出，这一现象的定量认识尤为重要。针对土地景观生态系统的复杂和模糊性，在建立评价指标的基础上，采用模糊综合评判的方法，对土地荒漠化程度进行定量评价，为荒漠化土地的预防和防治提供科学依据和决策支持。  相似文献   

河流水质风险评价的灰色-随机风险率方法   总被引：3，自引：2，他引：3  

胡国华  夏军  赵沛伦 《地理科学》2002,22(2):249-252

提出了量化影响河流水质的随机不确定性与灰色不确定性的水质超标灰色－随机风险率概念，建立了水质超标灰色－随机风险率评价模型。在水质单项参数评价模型中，将河流污染物浓度变量的分布处理成灰色概率分布，将污染物浓度超过水质类别标准值的风险率处理成灰色概率，即水质超标灰色－随机风险率。在水质综合评价模型中，河流水环境系统被考虑为担任某一使用可能的可靠性系统，而任意一种水质参数超标意味着河流水体使用功能不能得到应有的保证，也即表明水体综合评价超标，最后借鉴系统可靠性分析的理论和方法计算水质综合超标率。该方法应用于黄河花园口断面重金属污染风险评价。  相似文献   

关于水资源承载力理论与方法的研究   总被引：119，自引：3，他引：119  

朱一中  夏军  谈戈 《地理科学进展》2002,21(2):180-188

本文首先明确了水资源承载力的基本概念 ,指出可持续发展理论、水 -生态 -社会经济复合系统理论、二元模式下的水文循环机制和过程是水资源承载力研究的理论基础 ,对水资源承载力研究的基本内容、评价指标体系的建立和评价方法进行了较全面的概括和总结。  相似文献   

吉林省通榆县旅游资源模糊评价研究     

王国霞  佟连军  马延吉 《地理与地理信息科学》2002,18(1):107-110

该文基于模糊数学的理论和方法 ,从不同角度、不同层次对吉林省通榆县的旅游资源进行综合评价 ,并针对旅游资源特征 ,提出了发展旅游业的基本构思。  相似文献