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This study presented a quantitative comparison of cockpit and doline karst by examining the numbers and characteristics of typical types of landform entities that are developed in Guilin(Guangxi, China), La Alianza(PR, USA), Avalton(KY, USA), and Oolitic(IN, USA). Five types of landform entities were defined: isolated hill(IH), clustered hills(CHs), isolated sinkhole(IS), clustered sinkholes(CSs), and clustered hills with sinkholes(CHSs). An algorithm was developed to automatically identify these types of landform entities by examining the contour lines on topographic maps of two cockpit karst areas(Guilin and La Alianza) and two doline karst areas(Oolitic and Avalton). Within each specific study area, the CHSs is the least developed type yet with a larger size and higher relief. The IH and IS entities are smaller in size, lower in relief, and outnumber their clustered counterparts. The total numbers of these types of entities are quite different in cockpit and doline karst areas. Doline karst is characterized by more negative(IS and CSs) than positive(IH and IHs) landforms and vice versa for cockpit karst. For example, the Guilin study area has 1192 positive landform entities in total, which occupy 9.81% of the total study area. It has only 622 negative landform entities occupying only 3.91% of the total study area. By contrast, the doline karst in Oolitic has 130 negative while only 10 positive landform entities. The positive and negative landforms in Oolitic occupy 12.68% and 2.61% of the total study area, respectively. Furthermore, average relief and slope of the landform entities are much higher and steeper in the cockpit karst than the doline karst areas. For instance, the average slope of CHs in Alvaton is 3.90 degrees while it is 19.78 degrees in La Alianza. The average relief of CSs is 4.07 m and 34.29 m in Oolitic and Guilin respectively. Such a difference within a specific area or between the cockpit and doline karst may reveal different controls on the development of karst landscape. 相似文献
23.
本文通过对曾广鸿等人[1]提出的利用三次Bezier曲线拼接模型实现满足拓扑关系的折线武等值线曲线化的理论方法进行编程实践后,发现仅仅根据文中的方法不能完全正确地实现等值线的绘制,为此作者通过编程实践对该方法进行了补充与完善,文中详细完整地介绍了能完全满足拓扑关系的折线式等值线全参数曲线化的具体实现方法. 相似文献
24.
The US Topo is a new generation of digital topographic maps delivered by the US Geological Survey (USGS). These maps include contours in the traditional 7.5-min quadrangle format. The process for producing digital elevation contours has evolved over several years, but automated production of contours for the US Topo product began in 2010. This process, which is quite complex yet fairly elegant, automatically chooses the proper USGS quadrangle, captures the corresponding 1/3 as grid points from the national elevation data set (3D Elevation Program), and adjusts elevation data to better fit water features from the National Hydrography Dataset. After additional processing, such as identifying and tagging depressions, constructing proper contours across double-line streams, and omitting contours from water bodies, contours are automatically produced for the quadrangle. The resulting contours are then compared to the contours on the original (legacy) topographic map sheets, or to the 10-m contours from the original map sheets. Where the elevation surface used to generate the contours has been derived from the previously published contours for a quadrangle, the generated contours match the legacy contours quite well. Where newer elevation sources, such as lidar, originate the elevation surface, generated contours may vary significantly from the previous cartographically produced contours due to more accurate representations of the surface, and less reliance on cartographic interpretation. 相似文献
25.
中国典型等降水量线年代际空间演变 总被引:3,自引:1,他引:2
基于1960-2013年中国573个气象站的月降水量数据,选用普通克里金插值法生成典型等降水量线(200、400,800 mm),从等降水量线移动距离和移动趋势的角度分析了中国近54年典型等降水量线的时空演变特征。结果表明:(1) 200、400,800 mm等降水量线近54年的空间分布大致呈东北-西南走向,且从西北到东南有序排列。(2) 200 mm等降水量线在宁夏平原和西藏中西部波动强烈,且均有向东和向南偏移趋势。200 mm等降水量线在宁夏平原20世纪70、80年代、21世纪初东移,20世纪90年代、21世纪10年代初西移。西藏中西部自20世纪80年代起200 mm等降水量线有西移和北移态势,新疆北部200 mm等降水量线范围不断扩大。(3) 400 mm等降水量线在华北中东部波动强烈,20世纪70年代、21世纪00年代东移,20世纪80、90年代和21世纪10年代初西移,且整体有向东和向南的偏移趋势,但年代际波动大。(4) 800 mm等降水量线在秦岭-淮河一线波动强烈,20世纪80年代、21世纪00年代北移,20世纪70、90年代、21世纪10年代初南移,且纬度降低趋势较明显。 相似文献
26.
针对东海冲绳海槽地区的地震地质背景,对东海海域潜在的地震海啸进行了预研究. 假设了冲绳海槽在发生8.5级大地震,断层错距高达15 m的极端地震情况引发的海啸对中国东部沿海地区的影响. 初步数值模拟结果表明,该地震引发的海啸的最大初始波高为4.3 m,4小时左右传至浙江沿岸,近岸各处波高为1——2 m,其中局部地区波高为2.4 m;约7——8小时靠近上海海岸线(若震源在中冲绳海槽地区,海啸传到上海最快大约7小时),近岸波高约为1 m. 近岸区域地形变化复杂,海岛密布,局部地形条件可能会很大地影响实际各地点海啸波高,加上海啸在岸边爬高及港湾效应,估计波高还会升高. 给出了冲绳海槽南、中、北部发生潜在地震海啸的传播等时图. 笔者在东海设置了3个地震及海啸监测站,基于海啸模拟结果绘制了监测站处的海啸随时间演化曲线,分析了预研究成果对海啸预警可能发挥的作用. 相似文献
27.
Antonio Donato Nobre Luz Adriana Cuartas Marcos Rodrigo Momo Dirceu Luís Severo Adilson Pinheiro Carlos Afonso Nobre 《水文研究》2016,30(2):320-333
Tools for accurately predicting environmental risks, such as the location and spatial extent of potential inundation, are not widely available. A dependence on calibration and a lack of available flood data have prevented the widespread application of existing hydrodynamic methods for predicting the extent of inundation. We use the height above the nearest drainage (HAND) terrain model to develop a simple static approach for mapping the potential extent of inundation that does not depend on flood observations and extends beyond methods for mapping low‐lying areas. While relying on the contour concept, the method utilizes drainage‐normalized topography and flowpaths to delineate the relative vertical distances (drop) to the nearest river. The HAND‐delineated relative drop is an effective distributed predictor of flood potential, which is directly related to the river stage height. We validated the new HAND contour approach using a flood event in Southern Brazil for which high‐resolution maps were available. The results indicated that the flood hazard‐mapping method accurately predicted the inundation extent of the channel carrying the flood wave and the channels influenced by flooding. For channels positioned outside of the flood‐wave area, the method overestimated the actual flood extent. As an original static assessment of floodwaters across the landscape, the HAND contour method could be used to map flood hazards in areas with poor information and could promote the development of new methods for predicting hydrological hazards. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
28.
MEI Hualin WU Changhua Tianjin Institute of Geology Mineral Resources CAGS Tianjin. JIN Wei Changchun University of Earth Sciences Changchun Jilin Hao Zhiguo Liu Xinzhu 《《地质学报》英文版》1998,72(1):14-28
Four distinct lithe-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt. Wulashan-Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo-tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800-1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan-Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000-1200 MPa to 500-700 MPa. The PT paths of the Jining and Erda 相似文献
29.
The empirical bay shape model proposed by Hsu and Evans in 1989 for predicting the static planform of a pocket beach is expanded to enable the calculation of three-dimensional beach changes on a pocket beach with a seawall. The original formulation was developed on the basis of a second-order regression analysis. Unlike the one-line model of shoreline changes, the model of Hsu and Evans does not require repeated calculations of the wave field and shoreline position, because it was derived on the assumption of null sediment movement within a pocket beach in static equilibrium, hence without the need of applying the continuity condition of total sand volume in the calculation. The expanded model proposed by the present authors satisfies the total sand budget on a pocket beach, by taking into account the concept of depth change due to longshore sand transport. Model tests were carried out and the new model was further applied to the beach changes at Kemigawa on the northeast of Tokyo Bay in Chiba Prefecture, as well as at Oarai in Ibaraki Prefecture, Japan. On both locations, seawall has been installed as countermeasures against beach erosion, where wave sheltering effect of the main breakwater and beach changes in front of the seawall has also been observed. With this expansion, the present model can be applied to predict the three-dimensional beach changes on a coast with seawall on a pocket beach. 相似文献
30.
将SURFER软件应用到地下水位等值线图绘制中,并以希尼尔水库为例,研究采用不同插值方法下SURFER软件绘制等值线图的差异,提出了不同插值方法的适用范围。 相似文献