2004年6月17日四川宜宾4.5级地震烈度考察及灾害损失评估

2004年6月17日5时25分在四川省宜宾县境内发生的4.5级地震宏观震中位于白花镇与孔滩镇交界部位.震中区烈度为Ⅵ度区和Ⅴ度区,面积各为5km2和150km2.等震线分布总体形态呈长轴走向为北东向的椭圆状.震区建筑物出现一些破坏或损坏的现象.地震造成直接经济损失1 535万元,约占宜宾县2003年国民生产总值20.0429亿元的0.77%.     

基于ETM影像数据融合的土地覆盖分类研究

在ERDAS软件支持下，对ETM遥感影像数据的TM1-TM5，TM7与其全色波段TM8进行融合，采用主成分、乘积法、Brovey转换三种融合方法，重采样方法分别为邻域法、立方卷积法及双线性内插法。采用相同的训练样本区及最大似然法分类方法，对融合产生的9幅影像及未融合影像进行土地覆盖分类，通过对分类影像的Producers Accuracy，Users Accuracy，Kappa三者的精度数据和地物波谱信息的对比分析，在总体上，上述的影像融合方法对提高土地覆盖分类的精度不明显，但就某些地物类型来说，还是值得采用的；三种融合方法和三种重采样方式它们之问相比较而言，乘积法融合法和立方卷积重采样法相对较为可取。     

基于有向窗的自适应SIGMA中值滤波算法

提出了一种能够有效消除InSAR DEM噪声的自适应中值滤波算法:基于有向窗的自适应SIGMA中值滤波。分别采用中值滤波、基于高程的自适应SIGMA中值滤波和基于有向窗的自适应SIGMA中值滤波算法,对InSAR Tandem DEM和模拟DEM进行了滤波处理。结果表明,基于有向窗的自适应SIGMA中值滤波算法不仅能够更有效地消除噪声,而且能够更好地保留图像的边界特征。     

山东新泰太古代层状硫化物中的硫同位素非质量分馏效应

物理、化学和生物作用引起的热力学和巩俐学同位素分馏均为与质量有关的分馏。非质量同位素分馏效应应是由一些特殊的气相光化学反应引起的，它可以解释一些元素浓度，甚至单个同位素比值无法揭示的特殊的作用过程。笔者首次在山东新泰地区新太古代层状硫化物中观测到了明显的硫同位素非质量分馏效应。δ33S、δ34S呈线性排列，且与硫同位素质量分馏线平行，33S小于0。     

Accumulation rates and predominant atmospheric sources of natural and anthropogenic Hg and Pb on the Faroe Islands

A monolith representing 5420 ¹⁴C yr of peat accumulation was collected from a blanket bog at Myrarnar, Faroe Islands. The maximum Hg concentration (498 ng/g at a depth of 4.5 cm) coincides with the maximum concentration of anthropogenic Pb (111 μg/g). Age dating of recent peat accumulation using ²¹⁰Pb (CRS model) shows that the maxima in Hg and Pb concentrations occur at AD 1954 ± 2. These results, combined with the isotopic composition of Pb in that sample (²⁰⁶Pb/²⁰⁷Pb = 1.1720 ± 0.0017), suggest that coal burning was the dominant source of both elements. From the onset of peat accumulation (ca. 4286 BC) until AD 1385, the ratios Hg/Br and Hg/Se were constant (2.2 ± 0.5 × 10^-4 and 8.5 ± 1.8 × 10^-3, respectively). Since then, Hg/Br and Hg/Se values have increased, also reaching their maxima in AD 1954. The age date of the maximum concentrations of anthropogenic Hg and Pb in the Faroe Islands is consistent with a previous study of peat cores from Greenland and Denmark (dated using the atmospheric bomb pulse curve of ¹⁴C), which showed maximum concentrations in AD 1953.The average rate of atmospheric Hg accumulation from 1520 BC to AD 1385 was 1.27 ± 0.38 μg/m²/yr. The Br and Se concentrations and the background Hg/Br and Hg/Se ratios were used to calculate the average rate of natural Hg accumulation for the same period, 1.32 ± 0.36 μg/m²/yr and 1.34 ± 0.29 μg/m²/yr, respectively. These fluxes are similar to the preanthropogenic rates obtained using peat cores from Switzerland, southern Greenland, southern Ontario, Canada, and the northeastern United States. Episodic volcanic emissions and the continual supply of marine aerosols to the Faroe Islands, therefore, have not contributed significantly to the Hg inventory or the Hg accumulation rates, relative to these other areas. The maximum rate of Hg accumulation was 34 μg/m²/yr. The greatest fluxes of anthropogenic Hg accumulation calculated using Br and Se, respectively, were 26 and 31 μg/m²/yr. The rate of atmospheric Hg accumulation in 1998 (16 μg/m²/yr) is comparable to the values recently obtained by atmospheric transport modeling for Denmark, the Faroe Islands, and Greenland.     

基于Harris算子的遥感影像自适应特征提取方法

提出一种基于Harris算子的遥感影像自适应特征点信息提取新方法。在进行特征点自动提取时,该方法通过设计一种自适应的迭代策略,实现了特征点阈值的自动确定。在兼顾局部纹理信息的基础上,通过对影像预先的分块处理和邻近点剔除,保证了特征点在全幅影像中的均匀分布。杭州地区TM影像特征点的提取试验表明,该方法自动化程度高,提取的特征点分布均匀合理,能满足几何配准和几何纠正精度要求,具有较高的实用价值。     

Assessing catchment-scale spatial and temporal patterns of groundwater and stream salinity

Understanding catchment-scale patterns of groundwater and stream salinity are important in land- and water-salinity management. A large-scale assessment of groundwater and stream data was undertaken in the eastern Mt Lofty Ranges of South Australia using geographical information systems (GIS), regional scale hydrologic data, hydrograph separation and hydrochemical techniques. Results of the study show: (1) salts were mostly of marine origin (75%), while sulfate and bicarbonate from mineral weathering comprised most of the remainder, (2) elevated groundwater salinities and stable water isotopic compositions similar to mean rainfall indicated that plant transpiration was the primary salt accumulation mechanism, (3) key factors explaining groundwater salinity were geology and rainfall, with overall catchment salinity inversely proportional to average annual rainfall, and groundwater salinity ‘hotspots’ (EC >8 mS/cm) associated with geological formations comprising sulfidic marine siltstones and shales, (4) shallow groundwater correlated with elevated stream salinity, implying that baseflow contributed to stream salt loads, with most of the annual salt load (estimated to be 24,500 tonnes) occurring in winter when baseflow volume was highest. Salt-load analysis using stream data could be a practical, low-cost technique to rapidly target the investigation of problem areas within a catchment.     

Soil detachment and transport on field‐ and laboratory‐scale interrill areas: erosion processes and the size‐selectivity of eroded sediment

Field‐ and laboratory‐scale rainfall simulation experiments were carried out in an investigation of the temporal variability of erosion processes on interrill areas, and the effects of such variation upon sediment size characteristics. Poorly aggregated sandy soils from the semi‐arid environment of Senegal, West Africa, were used on both a 40 m² field plot and a 0·25 m² laboratory plot; rainfall intensity for all experiments was 70 mm h^?1 with a duration of 1 to 2 hours. Time‐series measurements were made of the quantity and the size distribution of eroded material: these permitted an estimate of the changing temporal balance between the main erosion processes (splash and wash). Results from both spatial scales showed a similar temporal pattern of runoff generation and sediment concentration. For both spatial scales, the dominant erosional process was detachment by raindrops; this resulted in a dynamic evolution of the soil surface under raindrop impact, with the rapid formation of a sieving crust followed by an erosion crust. However, a clear difference was observed between the two scales regarding the size of particles detached by both splash and wash. While all measured values were lower than the mean weight diameter (MWD) value of the original soil (mean 0·32 mm), demonstrating the size‐selective nature of wash and splash processes, the MWD values of washed and splashed particles at the field scale ranged from 0·08 to 0·16 mm and from 0·12 to 0·30 mm respectively, whereas the MWD values of washed and splashed particles at the laboratory scale ranged from 0·13 to 0·29 mm and from 0·21 to 0·32 mm respectively. Thus only at the field scale were the soil particles detached by splash notably coarser than those transported by wash. This suggests a transport‐limited erosion process at the field scale. Differences were also observed between the dynamics of the soil loss by wash at the two scales, since results showed wider scatter in the field compared to the laboratory experiments. This scatter is probably related to the change in soil surface characteristics due to the size‐selectivity of the erosion processes at this spatial scale. Copyright © 2006 John Wiley & Sons, Ltd.     

遥感影像配准误差传递模型及模拟分析

在遥感影像配准过程中,通常假设控制点是“完美的”。然而,在实际情况中,由于控制点本身不可避免的带有一定的误差导致这种假设在一定情况下并不成立,并且将会影响遥感影像几何校正的精度。普通最小二乘方法OLS(O rd inary Least Square)是遥感影像配准常用的校正估计模型,令人遗憾的是,在控制点存在误差的情况下,它的估计是有偏的,并且不能够正确传递和估计校正影像的误差大小。引入一致校正最小二乘方法CALS(ConsistentAd justed Least Squares),在此基础上提出的一个改进的方法,称之为松弛一致校正最小二乘方法RCALS(Relaxed ConsistentAd justed Least Squares)。这类回归模型具有改正控制点(解释变量)中的误差和跟踪回归模型中的误差传递的能力。为了验证CALS和RCALS模型的有效性,本文利用模拟影像进行分析。这里着重分析OLS,CALS和RCALS模型在几何校正过程中的比较。结果表明,RCALS和CALS的结果优于OLS估计结果。     

对城市活断层探测项目中地震地质数据建模的探讨

在城市活断层探测项目中,基于地震地质和活动构造研究的数据模型研究是相关应用领域中的重要问题。本文依据"中国地震活动断层探测技术系统"规程应用统一建模语言讨论和建立了地震地质数据模型,着重论述了地震地质数据模型与活动断层探测相关数据的组织方法,给出了地震地质基于ArcGIS的UML模型的空间和属性类结构图、类关系图表。在此基础上分析了地震地质UML模型的特点。