Erosion rates and sediment budgets in vineyards at 1-m resolution based on stock unearthing (Burgundy, France)   总被引：1，自引：0，他引：1  

Jrme Brenot  Amlie Quiquerez  Christophe Petit  Jean-Pierre Garcia 《Geomorphology》2008,100(3-4):345-355

A new and simple method is developed to efficiently quantify erosion and deposition rates based on stock unearthing measurements. This is applicable to spatial scales ranging from plot to hillslopes, and to time scales ranging from single hydrologic events to centennial scales. The method is applied to a plot area on vineyard hillslopes in Burgundy (Monthélie, France), with measurement of 4328 vine plants. A sediment budget established at the plot scale shows a mean soil lowering of 3.44 ± 1 cm over 20 years, involving a minimal erosion rate of 1.7 ± 0.5 mm yr^− 1. Locally, erosion rates can reach up to 8.2 ± 0.5 mm yr^− 1.This approach allows the sediment redistribution to be mapped and analyzed at 1-m resolution. It provides novel insights into the characterization of erosion patterns on pluri-decennial scales and into the analysis of spatial distribution of erosion processes on cultivated hillslopes.  相似文献   

空间光滑地震活动性模型中光滑函数的比较研究   总被引：2，自引：1，他引：1       下载免费PDF全文

徐伟进  高孟潭 《地震学报》2012,34(2):244-256

使用Frankel提出的基于空间光滑地震活动性模型的地震危险性分析方法,选择华南、华北、川滇3个地区的地震记录,比较分析了高斯、幂律和地震分形分布光滑函数3种光滑函数在不同地区的适用性．结果表明,使用交叉验证法可以为高斯光滑函数选取合适的相关距离c值,光滑得到的地震活动性模型能够真实反映研究区域的地震活动特征,根据活动性模型计算得出的峰值加速度(PGA)分布也符合人们对研究区域地震危险性的认识．幂律光滑函数适用于地震活动性较强的地区,且具有容易求取光滑参数的优点．光滑程度较低的幂律光滑函数不适用于地震活动性弱的地区,在该类地区应选择光滑程度较高的高斯光滑函数．地震分形分布光滑函数不适用于地震活动较强且地震活动强度差异较大的地区,其容易过分高估高震级地震对地震危险性的影响,而忽略了低震级地震对地震危险性的贡献．但对于地震活动较弱且地震活动强度差异较小的地区,可使用地震分形分布光滑函数,且同样具有容易求取光滑参数的优点．   相似文献   

小震密集带与地质活动断裂的关系研究     

冉志杰  张合  温超  杨岐炎  骆艳欣  彭远黔 《华北地震科学》2012,30(2):13-16

采用双差地震定位方法对1830年磁县7(1/2)级地震X区及其附近地区小震进行重新定位,划分出小震密集带,根据小震空间分布特征,研究X区范围内断裂构造与小震密集带之间的关系。结果表明,小震主要集中在NE向断裂与磁县—大名断裂交汇处以及断层切割区。  相似文献   

由GOCE高低卫卫跟踪数据反演地球重力场的模拟研究     

刘晓刚  孙文  李新星  周睿 《大地测量与地球动力学》2014,34(6):66-71

根据调和分析法、最小二乘法,建立利用扰动位数据解算地球重力场的实用数学模型。结果表明,采用不同数据量和不同采样率的观测数据对重力场模型解算结果有一定影响,不同分辨率的观测数据恢复重力场模型的精度差异较大,调和分析法精度优于最小二乘法。  相似文献   

汶川地震同震形变场的GPS和InSAR邻轨平滑校正与断层滑移精化反演   总被引：1，自引：1，他引：0       下载免费PDF全文

杨莹辉  陈强  刘国祥  程海琴  刘丽瑶  胡植庆 《地球物理学报》2014,57(5):1462-1476

为克服InSAR观测汶川地震同震形变场的邻轨不连续问题,提出联合GPS观测值与邻轨平滑约束的同震位移校正方法,采用GPS观测形变去除PALSAR轨道误差引入的残留平地相位,基于形变平滑条件校正邻轨干涉相位的不连续性.ALOS/PALSAR干涉处理结果表明,校正后同震形变场的准确度与平滑性得以显著提高,InSAR高相干点残差达3.6 cm,校正后精度提高约60%,低相干点精度提高约40%,校正后形变场的邻接平滑因子标准差减小约33%,验证了轨道误差校正与邻轨平滑约束方法的准确性与可靠性.进一步基于弹性半空间位错模型的断层滑移反演结果表明,断层滑移主要分布于映秀、北川和青川地区,集中于地壳深度0~16 km范围,最大滑动量（位于北川县城）约为9.0 m,GPS反演模型残差为5.5 cm,InSAR反演模型残差达9.2 cm,InSAR反演精度约有30%的显著提高,由模型反演计算得到的地震矩为8.0469×10²⁰ N·m.  相似文献   

A STATISTICAL PREDICTION MODEL FOR SPRING RAINFALL OVER NORTHERN CHINA BASED ON THE INTERANNUAL INCREMENT APPROACH     

范可 《热带气象学报(英文版)》2012,18(4):543-550

The spring (March-April-May) rainfall over northern China (SPRNC) is predicted by using the interannual increment approach. DY denotes the difference between the current year and previous years. The seasonal forecast model for the DY of SPRNC is constructed based on the data that are taken from the 1965-2002 period (38 years), in which six predictors are available no later than the current month of February. This is favorable so that the seasonal forecasts can be made one month ahead. Then, SPRNC and the percentage anomaly of SPRNC are obtained by the predicted DY of SPRNC. The model performs well in the prediction of the inter-annual variation of the DY of SPRNC during 1965-2002, with a correlation coefficient between the predicted and observed DY of SPRNC of 0.87. This accounts for 76% of the total variance, with a low value for the average root mean square error (RMSE) of 20%. Both the results of the hindcast for the period of 2003-2010 (eight years) and the cross-validation test for the period of 1965-2009 (45 years) illustrate the good prediction capability of the model, with a small mean relative error of 10%, an RMSE of 17% and a high rate of coherence of 87.5% for the hindcasts of the percentage anomaly of SPRNC.  相似文献   

Identification of coastal water quality by statistical analysis methods in Daya Bay, South China Sea   总被引：3，自引：0，他引：3  

Mei-Lin Wu  You-Shao Wang  Cui-Ci Sun  Haili Wang  Jian-Ping Yin 《Marine pollution bulletin》2010,60(6):852-5195

In this paper, cluster analysis (CA), principal component analysis (PCA) and the fuzzy logic approach were employed to evaluate the trophic status of water quality for 12 monitoring stations in Daya Bay in 2003. CA grouped the four seasons into four groups (winter, spring, summer and autumn) and the sampling sites into two groups (cluster DA: S1, S2, S4-S7, S9 and S12 and cluster DB: S3, S8, S10 and S11). PCA identified the temporal and spatial characteristics of trophic status in Daya Bay. Cluster DB, with higher concentrations of TP and DIN, is located in the western and northern parts of Daya Bay. Cluster DA, with the low Secchi, is located in the southern and eastern parts of Daya Bay. The fuzzy logic approach revealed more information about the temporal and spatial patterns of the trophic status of water quality. Chlorophyll a, TP and Secchi may be major factors for deteriorating water quality.  相似文献   

利用地脉动台阵记录反演场地浅层Vs结构     

董连成  陶夏新  师黎静  李广影 《岩土力学》2008,29(2):553-556

比较了影响Love波相速度频散曲线的主要因素,通过虚拟反演,说明了利用Love波相速度反演浅层剪切波速度结构的可行性,以地脉动台阵3分量观测记录提取的Love波相速度频散曲线为目标函数,利用遗传算法与单纯形法混合算法,分两种情况反演了某实际工程场地的浅层剪切波速度结构。结果表明,利用从地脉动台阵3分量观测资料中提取的Love波相速度反演工程场地浅层的剪切波速度Vs结构是一种很有前景的技术方法。  相似文献   

Calibration of the specific barrier model to Iranian plateau earthquakes and development of physically based attenuation relationships for Iran   总被引：1，自引：0，他引：1  

H. Zafarani  M. Mousavi  As. Noorzad  A. Ansari 《Soil Dynamics and Earthquake Engineering》2008,28(7):550-576

Earthquake ground-motion relationships for soil and rock sites in Iran have been developed based on the specific barrier model (SBM) used within the context of the stochastic modeling and calibrated against up-to-date Iranian strong-motion data. A total of 171 strong-motion accelerograms recorded at distances of up to 200 km from 24 earthquakes with moment magnitudes ranging from Mw 5.2 to 7.4 are used to determine the region-specific source parameters of this model. Regression analysis was conducted using the “random effects” methodology that considers both earthquake-to-earthquake (inter-event) variability and within-earthquake (intra-event) variability to effectively handle the problem of weighting observations from different earthquakes. The minimization of the error function in each iteration of the “random effects” procedure was performed using the genetic algorithm method. The residuals are examined against available Iranian strong-motion data to confirm that the model predictions are unbiased and that there are no significant residual trends with distance and magnitude. No evidence of self-similarity breakdown is observed between the source radius and its seismic moment. To verify the robustness of the results, tests were performed to confirm that the results are unchanged if the number of observations is changed by removing different randomly selected datasets from the original database. Stochastic simulations, using the derived SBM, are then performed to predict peak ground-motion and response spectra parameters for a wide range of magnitudes and distances. The stochastic SBM predictions agree well with the new empirical regression equations proposed for Iran, Europe and Middle East in the magnitude–distance ranges well represented by the data. It has been shown that the SBM of this study provides unbiased ground-motion estimates over the entire frequency range of most engineering interests (1–10 Hz) for the Iranian earthquakes. Our results are also important for the assessment of hazards in other seismically active environments in the Middle East and Mediterranean regions.  相似文献   

应用线性光谱分离技术研究喀斯特地区土地覆被变化——以贵州省关岭县为例   总被引：24，自引：3，他引：21  

万军  蔡运龙 《地理研究》2003,22(4):439-446

喀斯特地区土地覆被主要类型除了和非喀斯特地区一样的植被和裸露土壤外,还存在一个广泛分布的裸露基岩,一般遥感处理方法不具备直接定量提取这三类土地覆被参数的能力。基于地物光谱线性混合模型的线性光谱分离技术,可以在亚象元的尺度上直接获取植被覆盖、裸露土壤和裸露基岩等在各象元区域内的比例,非常适合用于喀斯特地区的土地覆被变化的研究。本文利用1987年2月17日和1999年12月27日LandsatTM各6波段遥感影像,使用ENVI软件,分离出植被、裸露土壤、裸露岩石和阴影等土地覆被丰度和RMS的空间分布。对比结果表明,研究区1987～1999年,植被覆盖率上升593%,裸露土壤面积下降1215%,裸露基岩面积上升408%。表明研究区尽管植被在恢复、水土流失总量在减少,但石漠化面积在明显上升,生态形势依旧严峻。  相似文献