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1.
Sinkhole formation in Florida is a common event. The Florida karst plain is significantly altered by human development and sinkholes cause considerable property damage throughout much of the state. We present in this paper a morphometric analysis of karst depressions in the Tampa Bay area, and the relation with the known distribution of sinkholes. We selected the Tampa Bay area because it is particularly susceptible to the evolution of karst depressions in relation with development of the built-up environment. Karst depressions were mapped from the 1:24,000 USGS topographic maps and a morphometric analysis was performed by using parameters such as shape, circularity index, perimeter, area, length, width, and orientation. Maps showing the distribution of depression density, and the sectors with greatest areas of karst depression were produced using a GIS. These results were compared with data compiled from the database of sinkhole occurrences in Florida maintained by the Florida Geological Survey. Our analysis demonstrates that the distribution of new sinkhole occurrences differs from the distribution of existing sinkholes, indicating that there are processes acting today that are influencing karst landscape formation that are different from those acting in the past.  相似文献   

2.
数字高程模型预处理方法的研究进展   总被引：3，自引：0，他引：3  
数字高程模型(Digital Elevation Model,简称DEM)是地形表面形态属性的数字化表达,被广泛应用于流域水文模拟中河网水系的提取.从DEM直接提取的河网水系及相关的流域地理空间信息,是分布式水文模拟的地理信息平台.由于DEM中洼地和平坦区的存在会影响水流方向的确定和数字河网的正确提取.因此在河网自动提取过程中必须首先对DEM数据进行预处理.本文对国内外各种DEM预处理方法进行了归纳总结.将DEM数据预处理方法分为两大类:分步处理法,以及一体化处理法.分步处理法按处理对象又可分为洼地处理方法和平坦区处理方法两部分;而一体化处理法则采用迭代算法同时对洼地和平地进行处理.  相似文献   

3.
The existing traditional methods of assessing the rates of soil loss have many limitations and are difficult to apply in the karst areas of Southwest China. Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of many depressions is not well understood. In this paper, the 137Cs technique was employed to investigate recent sedimentation rates in a Chinese polygonal karst depression. The results indicated that the sediment deposition rates ranged from 0.91 to 1.97 mm?a?1 in the period from 1963 to 2007, and the average sediment deposition rate and specific deposit yield of the catchment were estimated to be 1.47 mm?a?1 and 20 t?km?2?a?1, respectively. The results obtained were consistent with the local monitoring data of runoff plots, confirming the validity of the overall approach. It was shown that soil loss rates were very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the spacial distribution of surface soil and 137Cs inventories was affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon which exists widely in the karst areas and is significantly different from other places.  相似文献   

4.
Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants; yet the sedimentology of many depressions is not well understood in the world. In this paper, the 137Cs technique was employed to estimate recent sedimentation rates in a Chinese polygonal karst depression. The results indicate that the sediment deposition rates ranged from 0.91 to 1.97 mm year−1 from 1963 to 2007, and the average sediment deposition rate and specific deposit yield were estimated to be 1.47 mm year−1 and 20 t km−2 year−1, respectively. These results are consistent with the local monitoring data of runoff fields, which confirms the validity of the overall approach. This shows that the soil loss rate is very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the space distribution of surface soil and 137Cs inventories are affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon, which exists widely in karst areas, and it is significantly different from other places.  相似文献   

5.
岩溶研究中,通常会使用高分辨率卫星图像和地理空间数据识别、描绘岩溶发育及相关地质灾害发生的地貌特征。本文旨在利用ArcGIS10.0确定干涉合成孔径雷达数字高程模型（IFSAR-DEM）识别、量化和描述岩溶洼地。这种半自动岩溶洼地/天坑探测方法采用水流模拟法,并结合（1）流域划分;（2）下沉填充法提取洼地特征;（3）下沉深度测量及分类;（4）使用2013年至2014年谷歌高光谱卫星图像和数字地形模型对探测到的岩溶洼地进行验证。该方法已在薄荷省旁劳市进行的评估中进行了预测试。使用国家测绘资源信息局（菲律宾）1991年的1:50 000比例尺地形图进行的初步封闭洼地分析,发现旁劳岛有15个天坑。利用5米高分辨率IFSAR-DEM,共探测到820个天坑,其中424个根据详细的地面实况进行了描绘,以验证了岩溶洼地的存在。地表实况包含天坑大小、形状和深度等基本形态测量分析以消除误报数据。阈值设定为沉降深度大于1米,孔径大于10米,从而最大程度精确区分实际的天坑。这种基于GIS的工具有助于生成高分辨率岩溶塌陷易发区图,继而指导当地规划者、工程师及决策者进行开发规划和土地利用。   相似文献   

6.
 Arid karst landscapes that have been degraded by human activities provide a challenge for rehabilitation and an opportunity to test ideas about the stability and resilience of limestone ecosystems. The Nullarbor Plain is the largest arid karst area in Australia (220 000 km2) and is divided into extensive closed karstic depressions separated by low rocky ridges, while the dominant vegetation is chenopod shrubland. Since European settlement there has been considerable change in the vegetation, with significant reduction in shrub and grass cover over large areas of the plain. These changes are related to a state and transition model of vegetation dynamics which incorporates climatic variability, fire history and grazing pressure from sheep, kangaroos and rabbits. A partial sediment budget using 137Cs inventories reveals local and regional patterns of soil redistribution within this arid karst landscape. Rehabilitation of eroded soil in pastoral lands has been accomplished at several sites but is labour intensive and vulnerable to climatic fluctuations. Given the low stock numbers, limited number of people involved, and poor economic returns, it would be sensible to make pastoral activities on the Nullarbor secondary to conservation priorities. This would necessitate a change in land ethic to stewardship, with emphasis on rehabilitation and control of feral animals. Management of increased numbers of visitors to the caves and karst also requires that resource inventories and management plans for each area be drawn up and used. Received: 1 June 1995 · Accepted: 4 December 1995  相似文献   

7.
滇东南丘北区峰丛—洼地地貌形态特征分析   总被引：1，自引：0，他引：1  
王迪  许模  漆继红  张强 《中国岩溶》2010,29(3):239-245
云贵高原东南部丘北区为峰丛—洼地岩溶组合地貌。利用统计分析方法考察了该区48个岩溶洼地及峰体的形态参数特征;利用分形理论方法计算了不同高程的等高线和地表水系的分维数。结果表明:（1）洼地的平均边数为5.6,平均周长3.4km,平均面积0.8km2;（2）洼地的加深和扩大近于同步,原始地面对后期溶蚀面的发育起控制作用;（3）峰丛—洼地的形态分形特征对岩溶演化具有很好的响应关系,可溶岩区等高线分维数平均为1.30,非可溶岩区为1.16,地表水文网分维数为1.07,反映岩溶区地形变化复杂,地下水文网较发育,岩溶发育程度较高;（4）研究区岩溶发育仍处于幼年至壮年期,将继续缓慢发育。   相似文献   

8.
In Sahel-Doukkala, which is characterized by lands of a relatively low relief, global DEMs and DEMs generated from digitizing topographic maps, have been the primary source of several multidisciplinary researches. Although these products present a great value of the conducted research, the level of the given accuracy is not sufficient enough for detailed geospatial analysis. These requirements led us to generate a high-resolution DEM as an alternative of available global DEMs or/and DEMs generated from digitizing topographic maps. In this study, we present a workflow to extract high-resolution DEM at 5 m resolution and derived orthoimages from ALOS-PRISM data over Sahel-Doukkala, through photogrammetric techniques, using a variation of GCPs obtained from topographic maps at scale 1:25,000. The accuracy of the generated products is reported according to NSSDA standards. Using ten GCPs, a PRISM-DEM with 3.88 m vertical accuracy and 11.60 m horizontal accuracy, both at 95% confidence level is obtained. This DEM will serve as base dataset for further detailed geospatial analysis and mapping applications in order to identify the relationship between surface parameters and groundwater, and also to assess and understand all factors influencing the development of karst landscapes and consequently subsurface stability in the investigated area.  相似文献   

9.
以川西高原巴塘县、白玉县为研究对象,详细阐述研究区从三叠系到寒武系出露的主要可溶岩地层的分布、岩石成分、结构特征以及各地层的岩溶发育特征,系统总结出研究区可溶岩地层的特征和碳酸盐岩地层岩溶发育的规律。结果表明:研究区可溶地层呈北西南东向展布,明显受区域地质构造影响;岩溶地貌发育特征显示出与青藏高原主要地区岩溶地貌的一致性,属第三纪时期热带—亚热带环境下发育演化的覆盖型岩溶剥露地表而形成的古岩溶,且岩溶类型多样,形态与规模空间差异性明显;不同碳酸盐岩地层的岩溶发育程度统计显示,泥盆系溶蚀洼地所占面积最大,三叠系与志留系碳酸盐岩地层中溶蚀洼地个数较多,但发育密度低于泥盆系,二叠系溶蚀洼地个数与面积均为最小,石炭系地层由于碳酸盐岩纯度高且集中出露,溶蚀洼地发育密度最大。   相似文献   

10.
鄂西岩溶槽谷区洼地的水位响应特征及产流阈值估算   总被引：1，自引：0，他引：1  
廖春来  罗明明  周宏 《中国岩溶》2020,39(6):802-809
以湖北省兴山县黄粮镇刘家坝和龙湾两处岩溶洼地作为研究对象,利用其降雨、水文和土壤水等监测数据,探讨灌入式补给条件下洼地汇流的水位响应特征和产流特点,并基于降雨量和洼地内明渠流量的关系,采用数学拟合方程,估算两处洼地的降雨产流阈值,进而分析了影响产流阈值的因素。结果表明:降雨强度增大,产流阈值减小;土壤前期含水率越大,越有利于坡面产流;落水洞和岩溶泉水位与降雨有较好的同步响应关系,水位变化曲线随雨强大小分别表现出“陡升陡降”和“缓升缓降”的特点;刘家坝和龙湾洼地的产流阈值分别为7.4 mm和10.6 mm。   相似文献   

11.
Debris flows are a prevalent and destructive mass-wasting type in many mountainous regions throughout the world, yet the recent identification of a debris flow topographic signature has not been incorporated into landslide inventories. We have detected this signature in a digital elevation model of the mountainous Oconaluftee River basin of the southern Appalachians, USA, where we have conducted mass-wasting inventories. We evaluate the applicability of this topographic signature in debris flow mapping efforts using inventories created by semiautomated classification of topographic derivative and vegetation index maps. Debris flow detection was increased by 12 % when the inventory was limited to the portion of the landscape that exhibits the debris flow topographic signature. The extent of drainages with this topographic signature, which have areas of 6 to 35 km2, is corroborated by analyses of channel form, knickpoint and bedrock distributions, and hypsometry. This mass-wasting inventory technique provides a more focused approach to statistically characterize the land surface, which resulted in increased inventory proficiency across a landscape with an extensive and relatively well-documented debris flow history.  相似文献   

12.
为深化洼地空间分布及其影响因素的认识,以云南石林县为例,在ArcGIS中基于DEM提取洼地分布及相关数据,并运用K函数（Ripley’s K）、核密度函数、缓冲区、空间叠加等分析方法,探讨了该区洼地密度分布特征及地理环境对其的影响。结果表明:研究区洼地在8 km尺度上为聚集分布模式,可划分为高密度（＞6个?km-2）、中密度（5～6个?km-2）和低密度（＜5个?km-2）三个区域。受多种地理环境因素影响,研究区洼地密度在不同海拔段、坡度、起伏度、地层岩石和断层缓冲区上均有差异性表现;同时,岩层节理、断层方向在一定程度上控制了洼地长轴的发育。研究区潜在水文连通性、面积—高程积分值两个指标与洼地密度呈现良好的一致性,但两个指标所反映的喀斯特洼地的地貌学意义还需进一步研究。   相似文献   

13.
山克强 《中国岩溶》2021,40(2):334-345
数字高程模型可以定量描述地貌,而基于峰丛洼地实体的岩溶地貌量化统计方法目前尚未确立。文章在1:50 000地质测量的基础上,将西南岩溶区地质填图试点地区的地层重新划分组合为火山岩层组、碎屑岩层组、灰岩层组、白云岩层组、泥灰岩层组、灰岩碎屑互层层组、白云岩碎屑岩互层层组7种层组类型;基于1:50 000数字地形图构建了研究区数字高程模型（DEM）,通过空间分析技术建立了区域洼地锥峰DEM,以岩溶层组为统计单元,分析出各个单元的锥峰洼地数字特征,并定义锥峰洼地发育系数（k）,量化峰丛洼地发育程度,将研究区地貌划分为5种地貌类型:峰丛洼地（k＞8.5）,锥峰洼地极为发育;峰丛谷地（1.9＜k≤8.5）,锥峰较为发育,洼地中等发育;丘岭谷地（0.9＜k≤1.9）,锥峰弱发育,洼地极少发育;溶蚀中山（0＜k≤0.9）,锥峰、洼地极少发育;侵蚀中山（k=0）,发育冲沟,无岩溶形态发育。   相似文献   

14.
Landslide inventories are the most important data source for landslide process, susceptibility, hazard, and risk analyses. The objective of this study was to identify an effective method for mapping a landslide inventory for a large study area (19,186 km2) from Light Detection and Ranging (LiDAR) digital terrain model (DTM) derivatives. This inventory should in particular be optimized for statistical susceptibility modeling of earth and debris slides. We compared the mapping of a representative set of landslide bodies with polygons (earth and debris slides, earth flows, complex landslides, and areas with slides) and a substantially complete set of earth and debris slide main scarps with points by visual interpretation of LiDAR DTM derivatives. The effectiveness of the two mapping methods was estimated by evaluating the requirements on an inventory used for statistical susceptibility modeling and their fulfillment by our mapped inventories. The resulting landslide inventories improved the knowledge on landslide events in the study area and outlined the heterogeneity of the study area with respect to landslide susceptibility. The obtained effectiveness estimate demonstrated that none of our mapped inventories are perfect for statistical landslide susceptibility modeling. However, opposed to mapping polygons, mapping earth and debris slides with a point in the main scarp were most effective for statistical susceptibility modeling within large study areas. Therefore, earth and debris slides were mapped with points in the main scarp in entire Lower Austria. The advantages, drawbacks, and effectiveness of landslide mapping on the basis of LiDAR DTM derivatives compared to other imagery and techniques were discussed.  相似文献   

15.
Karst aquifers are highly susceptible to contamination, with numerous points of entry for contaminants through recharge features such as sinkholes, swallow holes and solutionally enlarged fractures. These recharge features may be filled or obscured at the surface, requiring the use of geophysical or remote sensing techniques for their identification. This study uses seismic refraction data collected at the Ft. Campbell Army Airfield (CAAF), Kentucky, USA, to test the hypothesis that refraction tomography is a useful tool for imaging bedrock depressions beneath thick overburden (greater than 20 m of unconsolidated sediment). Southeast of the main taxiway of CAAF seismic velocity tomograms imaged a bedrock low, possibly a closed depression, at a depth of 25 m that had been earlier identified through delay-time analysis of the same refraction data. Tomography suggests the bedrock low is about 250-m wide by 10-m deep at its widest point. High rates of contaminant vapor extraction over the western extension of this feature suggest a high concentration of contaminants above, and within, this filled bedrock low, the base of which may contain solutionally enlarged fractures (i.e. karst conduits) that could funnel these contaminants to the upper or lower bedrock aquifers. This study thus demonstrates the viability of seismic refraction tomography as a tool for identification of filled sinkholes and bedrock depressions in karst areas.  相似文献   

16.
铜陵市长江东路岩溶塌陷形成机制及土地适宜性分析   总被引：1，自引：0，他引：1  
孙凤贤 《安徽地质》2006,16(4):285-289
岩溶塌陷是铜陵市长江东路主要地质灾害类型,这种地质灾害现象,是在复杂的地质环境条件下产生的。本文在大量地质调查、分析与研究的基础上,通过对长江东路岩溶塌陷灾害的形成机理、产生条件的分析研究,并在研究这一灾害系统特性的基础上,预测分析了岩溶塌陷灾害的发展趋势,同时,根据铜陵市发展的实际情况和远期发展目标,对岩溶塌陷区的特征及土地的适宜性进行了评价分析,并在此基础上因地制宜的提出了工程建设过程中预防岩溶塌陷灾害的措施。  相似文献   

17.
Through utilizing water flow monitoring, rock scratching, soil wood piles and radionuclide 137Cs tracing in the Longhe karst ecological experimental site (hereinafter referred to“Longhe site”), Pingguo County, Guangxi Province, the features and values of soil erosion and soil leakage in different geomorphologic locations and land uses in the karst peak-cluster depressions are showed clearly. There are four kinds of geomorphologic locations in the karst peak-cluster depression, namely peaks, strip, slopes and depression. The soil leakage modulus in the peaks and strips respectively occupy 92.43% and 96.24% of the total mean soil erosion modulus at experimental sites. On the slope, soil leakage accounted for about 75%. At the bottom of depression, surface water was the main factor of soil erosion, and at last most soil leaked into underground rivers from sinkholes. The total soil erosion modulus and the contribution rates of relative surface soil erosion in regard of peaks, slopes and depressions gradually increased. There are also five major types of land use in the karst peak-cluster depressions, farmland, Kudingcha tea plantations, young Lignum Sappan fields, shrub-grassland and pastures. The soil erosion modulus of slope farmland has the highest value with an increasing trend year by year. But soil erosion modulus of other four land use types decreased by year, which shows the “grain for green” will result in better soil protection. By handling with rocky desertification and ecological rehabilitation in Longhe site, the mean soil erosion modulus of the karst peak-cluster depression has decreased about 80% from 2003 to 2015.  相似文献   

18.
Caves, springs, and large depressions of limestone karst formations are becoming more attractive tourist places and have potential importance on socio-economic development. The present study is a multi-scale point of view on limestone karst, from the space images to microscopic fabric. Here, the karst features consist of limestone formations of Cretaceous (Albian–Cenomanian) age of Tanuf Valley and Tertiary (Late Paleocene–Middle Eocene) age of Sur region of parts of Sultanate of Oman which are mapped in the visible near-infrared and shortwave infrared spectral bands of advanced spaceborne thermal emission and reflection radiometer (ASTER) using decorrelated stretch image processing technique and the occurrences of caves, springs, and depressions of the formations in the field were studied. The decorrelated RGB images of ASTER spectral bands 8, 3, and 1 discriminated well the limestone formations and associated lithology. The limestone formations of Tanuf valley (Natih formations of Hajar unit) are thick-bedded, massive, shallow marine limestone and clayey limestone, which have caves and springs. Large depressions are studied as collapsed structures at the boundary between Abat formations; they consist of gray to white marly or micritic limestone with chert nodules and Seeb Formation of bioclastic limestone, calcarenite, marl, and sandstone of Sur region. Interpretations of limestone formations, their occurrences and distributions of caves, springs and depressions of these regions are verified and confirmed in the field and studied in the laboratory. Occurrences of more springs and depressions in the limestone formations of the study sites are interpreted and located on the Google Earth image. The study proved the capability of ASTER sensor in mapping of limestone formations and recommends the technique to other geographical regions where similar geological questions need to be resolved.  相似文献   

19.
马山东部岩溶洼地谷地内涝特征与治理规划   总被引：2，自引：1，他引：1  
马山东部约94%的面积为碳酸盐岩分布区,岩溶洼地谷地发育,且封闭性好,内涝频繁发生。据调查,全区经常性发生内涝的洼地谷地多达170余处,受涝面积大于2. 1万亩,内涝具有周期性、多发性,以及分布面广、突发性强、治理难度大等特点。统计表明,本区内涝发生少者每年1～ 2次,多者可达5～ 7次,内涝淹没时间长的可达1～ 2个月。分析认为,持续的强降雨、封闭的地形地貌条件、地下管道排水不畅和洼地谷地远离排泄基准面等,是内涝形成的主要原因。在剖析加芳、古寨、古零等洼地谷地已有治涝工程失败教训的基础上,结合本区地理地质环境条件,有针对性地提出了对存在地表排泄基准面的地区宜实施排洪隧道工程治理、对无排泄基准面的洼地谷地区宜修建溶洼成库的洪涝治理方案与建议。   相似文献   

20.
Intra-continental depressions occurred in Central Arabia, within the evaporite-bearing Sulaiy Formation, and extends for over 550 km along N-S arcuate belt, passing through eastern Ar Riyadh, Saudi Arabia. They mark Jurassic/Cretaceous contact within the Interior Homocline of Central Arabia, accommodating Neogene and Quaternary deposits. Two en echelon major depressional areas were discovered, the northern major depressional area and the southern major depressional area. The first depressional area occurs between Al Artawiyah and Ad Dilam towns, following the arcuate Jurassic/Cretaceous contact. It contains five depressions: N-S Al Artwaiyah depression; NW-SE Ath Thumamah depression, northeast of Riyadh; NW-SE Jinadriyah depression, east of Riyadh; E-W Al Kharj depression; and N-S Ad Dilam depression. All five depressions seems to be formed by tectonic and subsequent geomorphic events, except for Al Artawiyah and Jinadriyah depression, which developed mainly by tectonic events. Southern major depressional area steps over to southwest of Ad Dilam, and occurs from Hawtat bani tamim to Layla towns. This Hawtah-Layla major depression trends N-S, and Cretaceous units strike NNE, which is a slightly oblique relationship, suggesting expression of deep-seated structures. Tectonic features were part of the Alpine-Himalayan orogeny, developing during Eocene. They followed by a geomorphic event (karsts and subsequent collapse) that took place during Mid Pleistocene. Ad Dilam depression is a surface expression of three oil and gas fields, while the southern major depression between Hawtat Bani Tamim and Layla towns is a surface expression of four oil and gas fields. Yet, other several depressional areas are also accommodating Quaternary desert sediments, and they contain economic resources, which therefore, worth further detailed studies.  相似文献   

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