工程与环境地球物理的发展现状与趋势——1997年工程与环境地球物理国际学术会议侧记   总被引：10，自引：1，他引：9  

曹俊兴  贺振华  朱介寿 《地球科学进展》1998,13(5):501-504

以1997年工程与环境地球物理国际学术会议的论文及报告为基础,分析了该学科的国内外发展现状,探讨了应予重视的研究方向。电阻率成像、地质雷达、层析成像、核地球物理近年发展较快;环境地球物理仍处于发展的初期阶段。近期应重视并加强对电磁成像、面波成像、污染监测调查技术、环境遥感监测技术、矿山地球物理技术和水下探测技术及地球物理场环境效应的研究。  相似文献   

土壤风蚀中有关土壤性质因子的研究历史与动向   总被引：10，自引：1，他引：9  

李小雁  李福兴 《中国沙漠》1998,18(1):91-95

国外土壤风蚀中有关土壤性质因子的研究历史可分为四个阶段：第一,定性描述阶段;第二,定量实验研究阶段;第三,运用综合因子建立和完善“通用风蚀方程式”阶段;第四,土壤风蚀土壤亚模型和预测系统的建立和动态研究阶段。国内对土壤风蚀的研究起步较晚,对于不同土类的土壤物理化学性质对风蚀的影响尚没有作深入研究。其历史大致可分为二个阶段：第一,野外观测研究;第二,风蚀的半定量实验研究。目前正由半定量向定量化、标准化、国际化以及动态研究方向发展。  相似文献   

超化井田二1煤层厚度变化规律定量研究   总被引：3，自引：3，他引：0  

曹代勇  刘钦甫 《煤田地质与勘探》1998,26(5):28-32

超化井田二１煤层空间展布具有分带性、定向性、等距性和岛列性等基本规律。趋势面分析揭示了井田尺度煤厚变化的主体特征;方向梯度和滑动窗口变异系数分析是对煤厚变异性定量描述的一种新参数。  相似文献   

Causes and Predictability of the 2021 Spring Southwestern China Severe Drought     

Yunyun LIU  Zeng-Zhen HU  Renguang WU  Xing YUAN 《大气科学进展》2022,39(10):1766-1776

In the spring of 2021, southwestern China (SWC) experienced extreme drought, accompanied by the highest seasonal-mean temperature record since 1961. This drought event occurred in the decaying phase of a La Ni?a event with negative geopotential height anomalies over the Philippine Sea, which is distinct from the historical perspective. Historically, spring drought over SWC is often linked to El Ni?o and strong western North Pacific subtropical high. Here, we show that the extreme drought in the spring of 2021 may be mainly driven by the atmospheric internal variability and amplified by the warming trend. Specifically, the evaporation increase due to the high temperature accounts for about 30% of drought severity, with the contributions of its linear trend portion being nearly 20% and the interannual variability portion being about 10%. Since the sea surface temperature forcing from the tropical central and eastern Pacific played a minor role in the occurrence of drought, it is a challenge for a climate model to capture the 2021 SWC drought beyond one-month lead times.  相似文献   

1979—2018年长江口及邻近海域风速和波高的分布特征与变化趋势     

吴秋原  史本伟  黄远光  杨世伦 《海洋通报》2020,39(4):447-455

本文基于欧洲中期天气预报中心 （ECMWF） 的 ERA5 与 ERA-Interim 再分析资料，提取长江口及其邻近海域1979— 2018 年间共 40 年的风场和海浪场数据，探讨该海域风浪和波高的时空变化特征，EOF 经验正交函数分解法分析结果显示风速与波高的数值在外海普遍高于近岸，且符合长江口所在东海海域受盛行东亚季风影响的特征。Mann-Kendall 检验法分析结果显示，在 1979—2018 年间该海域海表面年均风速呈增长趋势，平均增长速率为 0.228 cm/（s·a），累计增长 1.6 %；年均有效波高呈增长趋势，平均增长速率为 0.120 cm/a，累计增长 5.4 %；年风速和波高的极端值也呈不同程度的增长趋势。  相似文献   

Flood frequency under the influence of trends in the Pearl River basin,China: changing patterns,causes and implications          下载免费PDF全文

Qiang Zhang  Xihui Gu  Vijay P. Singh  Mingzhong Xiao  Chong‐Yu Xu 《水文研究》2015,29(6):1406-1417

Using a nonstationary flood frequency model, this study investigates the impact of trends on the estimation of flood frequencies and flood magnification factors. Analysis of annual peak streamflow data from 28 hydrological stations across the Pearl River basin, China, shows that: (1) northeast parts of the West and the North River basins are dominated by increasing annual peak streamflow, whereas decreasing trends of annual peak streamflow are prevailing in other regions of the Pearl River basin; (2) trends significantly impact the estimation of flood frequencies. The changing frequency of the same flood magnitude is related to the changing magnitude or significance/insignificance of trends, larger increasing frequency can be detected for stations with significant increasing trends of annual peak streamflow and vice versa, and smaller increasing magnitude for stations with not significant increasing annual peak streamflow, pointing to the critical impact of trends on estimation of flood frequencies; (3) larger‐than‐1 flood magnification factors are observed mainly in the northeast parts of the West River basin and in the North River basin, implying magnifying flood processes in these regions and a higher flood risk in comparison with design flood‐control standards; and (4) changes in hydrological extremes result from the integrated influence of human activities and climate change. Generally, magnifying flood regimes in the northeast Pearl River basin and in the North River basin are mainly the result of intensifying precipitation regime; smaller‐than‐1 flood magnification factors along the mainstream of the West River basin and also in the East River basin are the result of hydrological regulations of water reservoirs. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

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何案华  赵刚  薛娜  王军  郭藐西  郭柏林  付子忠 《大地测量与地球动力学》2009,29(4):51-54

??????????????????????????????????????????????????????????????????????????????????????????????????????仯??????????￡????????????????0.007 5?棬????????仯????????????????????????????????????????????????????????????????????????????????г????????????????????????????????????????  相似文献   

Trend detection in river flow series: 2. Flood and low-flow index series / Détection de tendance dans des séries de débit fluvial: 2. Séries d'indices de crue et d'étiage     

《水文科学杂志》2013,58(5)

Abstract

Major floods in Europe and North America during the past decade have provoked the question of whether or not they are an effect of a changing climate. This study investigates changes in observational data, using up to 100-year-long daily mean river flow records at 21 stations worldwide. Trends in seven flood and low-flow index series are assessed using Mann-Kendall and linear regression methods. Emphasis was on the comparison of trends in these flow index series, particularly in peak-over-threshold (POT) series as opposed to annual maximum (AM) river flow series. There is a larger number of significant trends in the AM than in the POT flood magnitude series, probably relating to the way the series are constructed. Low flood peaks occurring at the beginning or end of a time series with trend may be too low to be selected for the POT analysis. However, one peak per year will always be selected for the AM series, making the slope steeper and/or the series longer, resulting in a more significant trend. There is no general pattern of increasing or decreasing numbers or magnitudes of floods, but there are significant increases in half of the low-flow series.  相似文献   

Detection of trends in hydrological extremes for Canadian watersheds     

Donald H. Burn  Mohammed Sharif  Kan Zhang 《水文研究》2010,24(13):1781-1790

The potential impacts of climate change can alter the risk to critical infrastructure resulting from changes to the frequency and magnitude of extreme events. As well, the natural environment is affected by the hydrologic regime, and changes in high flows or low flows can have negative impacts on ecosystems. This article examines the detection of trends in extreme hydrological events, both high and low flow events, for streamflow gauging stations in Canada. The trend analysis involves the application of the Mann–Kendall non‐parametric test. A bootstrap resampling process has been used to determine the field significance of the trend results. A total of 68 gauging stations having a nominal record length of at least 50 years are analysed for two analysis periods of 50 and 40 years. The database of Canadian rivers investigated represents a diversity of hydrological conditions encompassing different extreme flow generating processes and reflects a national scale analysis of trends. The results reveal more trends than would be expected to occur by chance for most of the measures of extreme flow characteristics. Annual and spring maximum flows show decreasing trends in flow magnitude and decreasing trends in event timing (earlier events). Low flow magnitudes exhibit both decreasing and increasing trends. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

多波束测深趋势面系数的主成分估计          下载免费PDF全文

王海栋  柴洪洲  宋国大  王君 《海洋测绘》2009,29(5):5-7

在多波束测深趋势面滤波构建趋势面模型的过程中,其模型变量线性相关时,系数阵存在复共线性,因此将主成分估计的方法应用于趋势面模型系数的求解,从而避免了复共线性的影响,最后通过实测数据进行实验,分别利用最小二乘算法和主成分估计求解二次趋势面模型。比较计算结果,验证了主成分估计算法的有效性。  相似文献