A comparison of drainage networks derived from digital elevation models at two scales   总被引：2，自引：0，他引：2  

Xinhao Wang  Zhi-Yong Yin 《Journal of Hydrology》1998,210(1-4):221-241

Automated generation of drainage networks has become increasingly popular with powerful analytical functions in geographic information systems (GIS) and with the increased availability of digital elevation models (DEMs). This paper compares drainage networks derived from DEMs at two scales, 1:250 000 (250K) and 1:24 000 (24K), using various drainage parameters common in hydrology and geomorphology. The comparison of parameters derived from the 250K DEMs with those from the 24K DEMs in 20 basins ranging from 150 to 1000 km² in West Virginia shows that the goodness-of-fit between parameter estimates based on the DEMs varies. Results clearly show that superior estimations are produced from the 24K DEMs. Better estimates can be obtained from the 250K DEMs for stream length and frequency parameters than for gradient parameters. However, the estimation of the mean gradient parameters based on the 250K DEMs seems to improve with increasing terrain complexity. Finally, basin size does not strongly affect the accuracy of parameter estimates based on the 250K DEMs.  相似文献   

标定电流对标度值测量的影响和数字表标度值测量稳流仪     

李铁  朱兆才 《东北地震研究》1996,12(3):64-66

本文讨论了标定电流对标度值测量的影响，并介绍了研制的数字表标度值稳定仪及其使用效果，该仪器标定电流在４－１９ｍＡ范围可手动选定，电流稳定精度小于０．０２ｍＡ，电流升，降的转换时间约３０ｓ，仪器结构紧凑，操作简便，可以满足地磁台工作需要。  相似文献   

Variability of sedimentary sequence: numerical modeling of the deposition-erosion process     

S. Ivanov 《International Journal of Earth Sciences》1996,85(1):12-18

Reinterpretation of field studies of bedload transport allowed some power-law relations to be obtained between different quantities. They were taken as a basis for the construction of a numerical model simulating bedload transport. The deposition-erosion process is presented as a sequence of individual events with intensities distributed according to a power law, characteristic of the regime of self-organized criticality. The model output (sedimentary cross sections with the model age of each of its elements) is rich in features resulting from the non-linearity of the underlying process. Analysis of the results of a series of numerical experiments provided an estimation of scale invariance of model sedimentary structures in space and time. These data are tested against observed regularities of spaciotemporal variability of real sedimentary sequences. Good agreement of these data makes it possible to extrapolate the scaling relations obtained to larger scales.  相似文献   

Refinement of the geopotential scale factorR 0 on     

David Nesvorný  Zdislav Šíma 《Earth, Moon, and Planets》1994,65(1):79-88

Altimetric measurements of the GEOSAT satellite were used for the determination of geopotential scale factorR ₀. The geopotential valueW ₀ on the geoid surface was then computed (W ₀ =GM/R ₀).The GEOSAT Geophysical Data Records (GDR's) covering an initial period of the Exact Repeat Mission (ERM) were filtered and processed. The necessary corrections were made in order to allow a precise detection of the sea surface. Gravitational geopotential, rotation and permanent tides were taken into account and the equipotential surface which is the best approximation of the sea surface was found.The determination of the potential valueW ₀ on the mean geoid surface in this way is very promising. An associated value withW ₀ - the geopotential scale factorR ₀ - seems to be a very good Earth dimension defining quantity. Moreover, there are many possible applications ofW ₀ (R ₀) in modern geophysics.The incorporation of one of these parameters - we now recommendR ₀ - into the set of the Primary Geodetic Parameters (PGP) is discussed and suggested.  相似文献   

沉积模型和储层随机建模   总被引：11，自引：9，他引：11  

刘振峰  郝天珧  杨长春 《地球物理学进展》2003,18(3):519-523

沉积模型是地层分析的重要工具，可以分为比例尺模型、概念模型和数学模型三大类型，其中数学模型又可分为确定性模型和随机模型。在实际地层分析及模拟工作中，特别是在小尺度问题的研究中，采用随机模型(或称统计学模型)往往更为有利。储层随机建模技术，作为这方面研究的典范，近年来成为储层预测和风险评价的一项较为有效的手段。然而，由于研究目标的复杂性，不同沉积模型之间的嵌套制约关系亦应引起重视。  相似文献   

Scale and the other: Levinas and geography   总被引：2，自引：0，他引：2  

Richard Howitt 《Geoforum》2002,33(3):299-313

This paper seeks to contribute to Geography's recent conversation of identity, landscape, scale and difference. It brings into dialogue previously divergent discussions about space, place and difference and proposes an approach that treats time, space, place and scale as co-equal conceptual and/or analytical elements of cultural landscapes. It argues that many philosophical debates about embodiment, emplacement and difference abstract a universalized notion of `place', `body' and `self' which confounds and conflates scale issues and consequently confuses the dialectical interplay of `time', `space', `being' and `culture' across scales. The paper takes the work of Emmanuel Levinas (1906-1995) and the discursive communities around it as a philosophical entry point into these debates.  相似文献   

气象要素场概率分布特征的模拟          下载免费PDF全文

张维锋  张军 《气象科学》2002,22(3):294-303

本文在气象要素区域概率分布模型－锯齿波模型的基础上，通过最小二乘法，拟合了该模型产生的区域气象要素概率分布曲线，并使用得到的拟合函数，模拟了实际气象要素场阈值的概率分布，验证了该模型的有效性，模拟结果表明：模拟值和实际统计值吻合较好，从而可以通过使用拟合函数，由某要素单站概率较方便，准确地得出该要素在区域范围的概率分布特征。  相似文献   

潮汐汊道形态动力过程研究综述   总被引：5，自引：0，他引：5  

高抒 《地球科学进展》2008,23(12):1237-1248

潮汐汊道是潮流作用占优势的沉积环境之一。潮汐汊道系统的口门水道往往是天然航道,在海港建设上具有重要性。从动力地貌学的观点来看,口门水道形态特征和演化研究涉及多种关键的海岸动力过程,因而具有重要的理论意义。均衡态下的潮汐汊道的口门过水断面面积与纳潮量之间存在着幂函数关系,当用传统的O′Brien方法来确定幂函数曲线时,指数n的值变化范围较大,这是由于参与统计分析的部分汊道系统未达到均衡态而造成的;而应用沉积动力学方法,所获的n值稳定在1.15左右,能更好地代表均衡态断面面积。在断面形状上,小型潮汐汊道可以形成宽浅水道中镶嵌次级水道的形态,以适应沉积物输运和堆积过程,提高汊道系统的稳定性。因此,小型潮汐汊道具有不同于大型潮汐汊道的时间—流速不对称特征。这些研究结果在小型汊道的开发和整治工程上具有应用价值。由于口门断面形态是与口门水道和潮流三角洲的整体特征及其动态相联系的,因此,今后的研究重点应是水动力条件、沉积物输运和堆积过程、水道形态之间的反馈关系,以及与纳潮海湾充填同步的潮流三角洲的生长过程,从而使水道地貌演化能够被定量地模拟。  相似文献   

保山金厂河大型铜铁多金属隐伏矿床   总被引：3，自引：1，他引：2  

周荣  陈均  吕永增  董文伟 《云南地质》2008,27(2):189-196

隐伏矿床位于金厂河隆起核部上、下两层矽卡岩化带中,垂向上Pb、Zn—Cu、Cu、Fe—Fe多层楼结构,水平上Fe、Cu—Pb、Zn—Cu分带。属热液交代矽卡岩型铜铁多金属矿床。  相似文献   

楚雄盆地上三叠统储集体成因类型及几何模式     

赖生华 《云南地质》2007,26(3):315-321

楚雄盆地经历多期构造变形.晚三叠世,盆地北部由盆底扇深水环境过渡到沿岸砂坝和三角洲环境.该时期形成辫状河道砂、砾岩体、滨滩砂岩体,河口坝砂岩体和分流河道充填砂岩体四类储集体,构成三种相结合,即扇储集体、三角洲前缘储集体和三角洲平原储集体,几何形态对应为透镜状、带状和不规则状.  相似文献