贵州省不同地貌形态类型土壤侵蚀强度变化的定量分析   总被引：1，自引：0，他引：1  

赵青松  兰安军  范泽孟  杨青 《地球信息科学学报》2020,22(7):1555-1566

如何揭示不同地貌形态类型区土壤侵蚀强度变化,尤其是在生态环境比较脆弱的喀斯特区域,是地方生态保护战略实施亟需研究的关键问题之一。本文基于ALOS、ZY-3、GF-1、Landsat和GDEMV2遥感影像数据,以及2762条野外采样验证数据,参照国家在喀斯特与非喀斯特地区土壤侵蚀不同分类标准,实现10 m×10 m分辨率的贵州省2010年和2015年土壤侵蚀空间信息数据提取。进而结合贵州省地貌数据,通过构建贵州省土壤侵蚀的时空分析模型,实现对不同地貌形态类型,尤其是喀斯特区域和非喀斯特区域的土壤侵蚀强度的时空变化进行定量分析。结果显示：在2010—2015年,贵州省中—高海拔区域土壤侵蚀变化的动态度高于低海拔区域,土壤侵蚀强度总体呈下降趋势,下降总面积达6468.13 km2。喀斯特区域的土壤侵蚀变化广度高于非喀斯特区域的土壤侵蚀变化广度,而且变化趋势基本上是从高一级的侵蚀强度向低一级的侵蚀强度变化。高盆地、中山、高中山土壤侵蚀强度减弱趋势明显高于其他地貌类型的趋势,但高中山仍是喀斯特与非喀斯特区土壤侵蚀增强变化较为明显的区域。这说明自21世纪以来,在贵州喀斯特区域实施的生态修复工程和生态环境保护政策在土壤侵蚀防治过程中发挥了主导性作用,在今后贵州省进行土壤侵蚀防治的过程中,除了喀斯特区域的防治外,还需要同时注意非喀斯特区域的防治。  相似文献   

Characteristics of turbulence over the semi-fixed desert area north of Xinjiang,China     

Ali Mamtimin  Yu Wang  Hajigul Sayit  Xing Hua Yang  Fan Yang  Wen Huo  Chenglong Zhou  Lili Jin 《地球表面变化过程与地形》2021,46(12):2365-2378

As the largest fixed and semi-fixed desert in China, the Gurbantünggüt Desert undergoes a long period of snow cover in the winter and the rapid growth of ephemeral plants in the spring, presenting obvious seasonal changes in the underlying desert surface type, which can lead to variation in the turbulence of the near-surface boundary layer turbulence over the desert. In this study, gradient tower data and eddy covariance data from 2017 were analysed to investigate the turbulence characteristics of the different surface boundary layers in the hinterland of the Gurbantünggüt Desert. The results indicate that stable atmospheric conditions in the desert occur exclusively during the early morning and at night in the desert, and the onset and duration of this stable state varies seasonally. Two regimes of intermittent turbulence occur during the night, a weak turbulent regime that occurs when the wind speed is less than the threshold and a strong turbulent regime when the wind speed exceeds the threshold, and different wind speed thresholds were observed at each level. These parameters follow a seasonal pattern of summer (July) > spring (April) > autumn (October) > winter (January) in terms of magnitude. The mean turbulence intensities of the along-wind, cross-wind and vertical wind are 0.5, 0.47 and 0.14, respectively, with I_u > I_v > I_w. The normalized standard deviation of the wind velocity components (σ_u, σ_v and σ_w) generally satisfies a 1/3 power-law relation. Our results show that the night-time turbulence regime classification for the Gurbantünggüt Desert strongly depends on meteorological and orographic features, and the intermittent turbulent events have the non-stationarity of the flow in common. The results can contribute to the study of land surface processes, climate change and desertification in inland arid desert areas.  相似文献   

青海地区地震磁扰动异常特征研究   总被引：1，自引：1，他引：0       下载免费PDF全文

李霞  冯丽丽  赵玉红  刘磊  苟智栋 《地震工程学报》2021,43(1):99-104,112

以青海地区8个测点磁通门秒采样观测数据为研究对象,利用地磁垂直强度极化法结合该区域中强地震背景进行分析。基于极化背景场变化特征提取震磁异常在研究区实际应用中取得以下认识:多台站同步极化高值异常对于2个月以内青海地区5级左右及以上地震有一定映震能力,且异常具有一定信度;测点密度均匀分布情况下,震中位置基本位于极化高值区域。  相似文献   

机载激光雷达平面精度评价方法研究     

王圣尧 《测绘与空间地理信息》2013,36(7):54-56

目前,机载激光雷达数据的高程精度一般在10～20 cm,平面精度为0.5～1 m,所以大多学者和生产厂家关注高程精度较多,故而高程精度的评价方法相对成熟,而平面精度的评价方法则有待完善。本文介绍的几种方法,立足于实际工作中发现的问题,具体情况具体分析,旨在能寻求最接近平面精度真值的表达方法,为将来平面精度评价成熟而通用的方法寻求道路。  相似文献   

Structural behaviour and design criteria of under‐deck cable‐stayed bridges subjected to seismic action     

Alfredo Camara  Ana M. Ruiz‐Teran  Peter J. Stafford 《地震工程与结构动力学》2013,42(6):891-912

  相似文献   

Book Review     

DECLAN CONWAY  BERNARD FRANCOU  LINDA SEE  Z. W. KUNDZEWICZ 《水文科学杂志》2013,58(2):323-327

Abstract

The instantaneous unit hydrograph (IUH) of a watershed is the result of one instantaneous unit of rainfall excess distributed uniformly over the watershed. Although the geomorphological characteristics of the basin remain relatively constant, the variable characteristics of storms cause variations in the shape of the resulting hydrographs. It is, therefore, inadequate to use one typical IUH to represent the hydrological response generated from any specific storm. In this study, a variable IUH was derived that directly reflects the time-varying rainfall intensity during storms. The rainfall intensity used to generate the variable IUH at time t is the mean rainfall intensity occurring from the time t—T _c to t in which T _c is the watershed time of concentration. Hydrological records from three watersheds in Taiwan were used to demonstrate the applicability of the proposed model. The results show that better simulations can be obtained by using the proposed model than by using the conventional unit hydrograph method, especially for concentrated rainstorm cases.  相似文献   

Spatial disaggregation and intensity correction of TRMM-based rainfall time series for hydrological applications in dryland catchments     

E. Tarnavsky  M. Mulligan  G. Husak 《水文科学杂志》2013,58(2):248-264

Abstract

A novel approach is presented for combining spatial and temporal detail from newly available TRMM-based data sets to derive hourly rainfall intensities at 1-km spatial resolution for hydrological modelling applications. Time series of rainfall intensities derived from 3-hourly 0.25° TRMM 3B42 data are merged with a 1-km gridded rainfall climatology based on TRMM 2B31 data to account for the sub-grid spatial distribution of rainfall intensities within coarse-scale 0.25° grid cells. The method is implemented for two dryland catchments in Tunisia and Senegal, and validated against gauge data. The outcomes of the validation show that the spatially disaggregated and intensity corrected TRMM time series more closely approximate ground-based measurements than non-corrected data. The method introduced here enables the generation of rainfall intensity time series with realistic temporal and spatial detail for dynamic modelling of runoff and infiltration processes that are especially important to water resource management in arid regions.

Editor D. Koutsoyiannis

Citation Tarnavsky, E., Mulligan, M. and Husak, G., 2012. Spatial disaggregation and intensity correction of TRMM-based rainfall time series for hydrological applications in dryland catchments. Hydrological Sciences Journal, 57 (2), 248–264.  相似文献   

Petrography and geochemistry of Jumara Dome sediments,Kachchh Basin: Implications for provenance,tectonic setting and weathering intensity   总被引：1，自引：1，他引：0  

A. H. M. Ahmad  K. N. Noufal  Alam M. Masroor  Tavheed Khan 《中国地球化学学报》2014,33(1):9-23

In the Kachchh Mainland, the Jumara Dome mixed carbonate-siliciclastic succession is represented by the Jhurio and Patcham formations and siliciclastic-dominating Chari Formation （Bathonian to Oxfordian）. The Ju- mara Dome sediments were deposited during sea-level fluctuating, and were interrupted by storms in the shallow marine environment. The sandstones are generally medium-grained, moderately sorted, subangular to subrounded and of low sphericity. The sandstones are mineralogically mature and mainly composed of quartzarenite and subar- kose. The plots of petrofacies in the Qt-F-L, Qm-F-Lt, Qp-Lv-Ls and Qm-P-K ternary diagrams suggest mainly the basement uplift source （craton interior） in rifted continental margin basin setting. The sandstones were cemented by carbonate, iron oxide and silica overgrowth. The Chemical Index of Alteration values （73% sandstone and 81% shale） indicate high weathering conditions in the source area. Overall study suggests that such strong chemical weathering conditions are of unconformity with worldwide humid and warm climates during the Jurassic period. Positive correlations between A1203 and Fe203, TiO2, Na20, MgO, K20 are evident. A high correlation coefficient between A1203 and K20 in shale samples suggests that clay minerals control the major oxides, The analogous con- tents of Si, A1, Ti, LREE and TTE in the shale to PAAS with slightly depleted values of other elements ascribe a PAAS like source （granitic gneiss and minor mafics） to the present study. The petrographic and geochemical data strongly suggest that the studied sandstones/shales were deposited on a passive margin of the stable intracratonic basin.  相似文献   

同步辐射X射线荧光光谱测定沉积物中元素含量的归一方法研究——以四海龙湾纹层沉积物为例     

凌媛  孙青  朱庆增  陈栋梁  徐伟  谢曼曼  单雅冰  王宁  储国强 《第四纪研究》2014,34(6)

同步辐射X射线荧光光谱分析(SRXRF)是一种基于同步加速器光源与X射线荧光光谱分析(XRF)相结合的原位分析方法,可以直接对沉积物进行扫描获得每个点的能谱图,从而计算元素含量的相对变化.但是由于荧光光谱定性和定量分析中存在的问题,国内发表文献中各种XRF原位分析数据均以相对含量或者计数表示.本文通过对各种标准物质(土壤、沉积物和岩石)的SRXRF分析,结合标准样品的定量数据,对同步辐射X射线荧光光谱的定量方法进行了研究.鉴于元素质量数和谱线强度的差异,不同元素需要运用不同的归一方法.对于K和Ca元素,采用ROI0-195背景归一;Ti元素采用ROI293-303背景归一;Mn元素采用ROI214-222背景归一;而较高序数的元素Fe采用拟合康普顿散射峰归一.通过上述归一方法,我们获得了K、Ca、Ti、Mn和Fe元素的定量标准曲线,相关系数分别为0.89、0.98、0.96、0.93和0.98.运用标准样品对各元素的定量标准曲线进行检验,结果表明:Fe元素含量预测的平均相对偏差小于10％,K、Ca和Ti的平均相对偏差小于20％,Mn的相对偏差较大,为35.9％.从总体上看,SRXRF获得的数据可以基本满足湖泊沉积物中元素分析的定量化需求.为验证SRXRF方法能否揭示元素含量的季节性变化,我们对四海龙湾纹层沉积物进行了分析,按选定的归一方法计算样品中元素特征谱线的强度,利用各元素的标准曲线计算岩芯沉积物中元素含量.K、Ca、Ti、Mn和Fe元素含量具有明显的季节韵律变化,浅色碎屑微层中Ti和Ca含量较高,而Mn和Fe丰度的高值对应于暗色有机质-碎屑混合层.初步研究结果表明同步辐射X射线荧光光谱分析可以揭示湖泊中沉积的元素的季节性变化,对研究过去季节-年尺度的古气候、古环境变化具有重要的科学意义.  相似文献   

Environmental drivers of phytoplankton crops and taxonomic composition in northeastern Antarctic Peninsula adjacent sea area     

Yubin Feng  Dong Li  Jun Zhao  Zhengbing Han  Jianming Pan  Gaojing Fan  Haisheng Zhang  Ji Hu  Haifeng Zhang  Jiaqi Wu  Qiuhong Zhu 《海洋学报(英文版)》2022,41(1):99-117

The ecosystem of the sea region adjacent to the Antarctic Peninsula is undergoing remarkable physical and biological changes, in the context of global warming. However, understanding of the dynamics of phytoplankton taxonomic composition in this marginal ice zone remains unclear. In this study, seawater samples collected from 36 stations in the northeastern Antarctic Peninsula were analyzed for nutrients and phytoplankton pigments.Combining with CHEMTAX analysis, remote sensing data, and physico...  相似文献