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1.
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2.
The study of the interaction of mud-flows with obstacles is important to define inundation zones in urban areas and to design the possible structural countermeasures. The paper numerically investigates the impact of a mud-flow on rigid obstacles to evaluate the force acting on them using two different depth-integrated theoretical models, Single-Phase Model(SPM) and Two-Phase Model(TPM), to compare their performance and limits. In the first one the water-sediment mixture is represented as a homogeneous continuum described by a shearthinning power-law rheology. Alternatively, the twophase model proposed by Di Cristo et al in 2016 is used, which separately accounts for the liquid and solid phases. The considered test cases are represented by a 1D landslide flowing on a steep slope impacting on a rigid wall and a 2D mud dam-break flowing on a horizontal bottom in presence of single and multiple rigid obstacles. In the 1D test case, characterized by a very steep slope, the Two-Phase Model predicts the separation between the two phases with a significant longitudinal variation of the solid concentration. In this case the results indicate appreciable differences between the two models in the estimation of both the wave celerity and the magnitude of the impact, with an overestimation of the peak force when using the Single-Phase Model. In the 2D test-cases, where the liquid and solid phases remain mixed, even if the flow fields predicted by the two models present some differences, the essential features of the interaction with the obstacles, along with the maximum impact force, are comparable. 相似文献
3.
线性加权回归模型的高原山地区域降水空间插值研究 总被引：3，自引：1，他引：2
在山地和高原区域,地形对降水影响比较显著。常规空间插值方法通常不考虑地形要素,插值精度有限。考虑到降水量与高程存在较强的相关关系,采用局部线性加权回归模型预测山地和高原区域的降水分布。推导了回归计算公式,并在ArcGIS 9.0中编程实现算法。选取美国德克萨斯州西北部地区进行局部线性加权回归空间插值,并与普通Kriging、倒距离加权法比较。误差分析表明:在地形复杂的地区,线性加权回归模型比传统方法有优势。 相似文献
4.
Floods are one of the most common natural hazards occurring all around the world. However, the knowledge of the origins of a food and its possible magnitude in a given region remains unclear yet. This lack of understanding is particularly acute in mountainous regions with large degrees in Sichuan Province, China, where runoff is seldom measured. The nature of streamflow in a region is related to the time and spatial distribution of rainfall quantity and watershed geomorphology. The geomorphologic characteristics are the channel network and surrounding landscape which transform the rainfall input into an output hydrograph at the outlet of the watershed. With the given geomorphologic properties of the watershed, theoretically the hydrological response function can be determined hydraulically without using any recorded data of past rainfall or runoff events. In this study, a kinematic-wave-based geomorphologic instantaneous unit hydrograph (KW-GIUH) model was adopted and verified to estimate runoff in ungauged areas. Two mountain watersheds, the Yingjing River watershed and Tianquan River watershed in Sichuan were selected as study sites. The geomorphologic factors of the two watersheds were obtained by using a digital elevation model (DEM) based on the topographic database obtained from the Shuttle Radar Topography Mission of US’s NASA. The tests of the model on the two watersheds were performed both at gauged and ungauged sites. Comparison between the simulated and observed hydrographs for a number of rainstorms at the gauged sites indicated the potential of the KW-GIUH model as a useful tool for runoff analysis in these regions. Moreover, to simulate possible concentrated rainstorms that could result in serious flooding in these areas, synthetic rainfall hyetographs were adopted as input to the KW-GIUH model to obtain the flow hydrographs at two ungauged sites for different return period conditions. Hydroeconomic analysis can be performed in the future to select the optimum design return period for determining the flood control work. 相似文献
5.
Leaf Area Index(LAI)is a key parameter in vegetation analysis and management,especially for mountain areas.The accurate retrieval of LAI based on remote sensing data is very necessary.In a study at the Dayekou forest center in Heihe watershed of Gansu Province,we determined the LAI based on topographic corrections of a SPOT-5.The large variation in the mountain terrain required preprocessing of the SPOT-5 image,except when orthorectification, radiation calibration and atmospheric correction were used.These required acquisition of surface reflectance and several vegetation indexes and linkage to field measured LAI values.Statistical regression models were used to link LAI and vegetation indexes.The quadratic polynomial model between LAI and SAVI (L=0.35)was determined as the optimal model considering the R and R2 value.A second group of LAI data were reserved to validate the retrieval result.The model was applied to create a distribution map of LAI in the area.Comparison with an uncorrected SPOT-5 image showed that topographic correction is necessary for determination of LAI in mountain areas. 相似文献
6.
科学界定山地和山区类型是认识山地、因地制宜促进山区可持续发展的基础,可为山区分类开发、分类施策提供依据。本文采用均值变点法确定滑动窗口尺寸,运用空间分析工具对SRTM进行处理以获取山地坡度、起伏度,并提取了黔桂喀斯特各类山地空间范围和规模,以此对县级层面黔桂喀斯特山区类型进行了划分。主要结论如下：①二次使用均值变点法确定移动窗口面积与平均地形起伏度拟合的对数曲线拐点,其表征的是黔桂喀斯特山区地形起伏度最佳统计单元—移动窗口面积为6.50 km2。②黔桂喀斯特山地占比大,山地与非山地面积之比约为89:11,且山地省际空间分异明显,贵州喀斯特山地以中山、中低山为主,占贵州部分的57%;而广西喀斯特山地以丘陵为主,占广西部分的59%。③黔桂喀斯特山地区均为山区县,其中,18个纯丘陵县、10个半山区县、15个准山区县、21个显山区县、32个整山区县。整山区县个数多,多分布于乌蒙山区和黔桂峰丛洼地山区,多数为国家扶贫开发工作重点县。 相似文献
7.
This paper presents debris-flow numerical simulations using the Hyper KANAKO system, developed by the authors. The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface (GUI); hence, a user can easily produce appropriate landform data for simulations using standard laser profiler data, and visualize the results using a GIS. Hyper KANAKO was applied to the streams around Kiyomizu-dera in Kyoto, Japan. Kiyomizu-dera is a famous temple in Japan which is visited by numerous tourists throughout the year. We simulated a disaster scenario of debris flow caused by torrential rain. We set the hydrograph using rainfall intensity data, and set the landform data using information from the Geospatial Information Authority of Japan (GSI) and a digital elevation model (DEM). We evaluated different mesh sizes and also used a digital surface model (DSM) to consider the building heights. The simulation results showed that with small mesh size, the debris flow moved through the roads, which seems realistic for a disaster situation. When buildings were considered, the flow direction changed, and a 1-m flow depth, which was deeper than in other cases, appeared in the flow path. This may pose a dangerous situation for evacuations. 相似文献
8.
On the criteria to create a susceptibility map to debris flow at a regional scale using Flow-R 总被引：1，自引：1，他引：0
Studies on susceptibility to debris flows at regional scale(100-1000 km~2) are important for the protection and management of mountain areas. To reach this objective, routing models, mainly based on land topography, can be used to predict susceptible areas rapidly while necessitating few input data. In this research, Flow-R model is implemented to create the susceptibility map for the debris flow of the Vizze Valley(BZ, North-Eastern Italy; 134 km~2). The analysis considers the model application at local scale for three sub-catchments and then it explores the model upscaling at the regional scale by verifying two methods to generate the source areas of debris-flow initiation. Using data of an extreme event occurred in the Vizze Valley(4 August 2012) and historical information, the modeling verification highlights that the propagation parameters are relatively simple to set in order to obtain correct runout distances. A double DTM filtering-using a threshold for the upslope contributing area(0.1 km~2) and a threshold for the terrain-slope angle(15°)-provides a satisfactory prediction of source areas and susceptibility map within the geological conditions of the Vizze Valley. 相似文献
9.
山城眺望空间OSCA模型构建及应用 总被引：2，自引：0，他引：2
山体是大自然赋予城市的天然景观资源,通过山与城市中建筑群构成的山城空间关系,可形成多类型的眺望景观。当前山城眺望景观在建设热潮中不断被破坏,逐渐消失在林立的高楼中,需要进行一定的控制和保护。以济南市中心城区为例,基于眺望控制分区,寻找城市建筑发展演变、分区建设的规律,结合元胞自动机与多智能体,提出基于眺望景观控制下的山城眺望空间CA-OSCA模型（Overlooking Space Cellular Automata）,构建山城眺望空间演变模型。利用GIS等数据分析平台,对模拟结果进行分析,构建真实城市空间下的未来山城眺望空间景观三维模型,以更加直观、真实地方法探讨在眺望景观分区控制的影响下,未来城市空间结构的发展模式,最终为未来山城眺望景观空间的控制与保护以及眺望景观保护下,山城城市未来空间发展结构提出发展策略。 相似文献
10.
P. B. Hunukumbura S.B. Weerakoon Srikantha Herath 《山地科学学报》2007,4(4):309-320
A model to derive direct runoff hydrograph for an ungauged basin using the physical properties of the basin is presented. The basin is divided into grid cells and canal elements. Overland flow is generated from each grid cell of the basin by application of continuous effective rainfall of 1 mm/hr to the basin. The flow generated is routed through downstream grid cells and the canal elements using the kinematic wave approach. The travel time for direct runoff from each grid cell to the basin outlet is calculated and the S-curve is derived for the basin. The S-curve is used to derive the unit hydrograph of a given duration for the basin. The model, referred as Cell-basin model was applied to the Upper Kotmale Basin in Sri Lanka and the model predictions of direct runoff hydrographs for rainfall events agreed with the observations to a reasonable accuracy. Comparison of the unit hydrographs obtained from the model and from the conventional Snyder’s synthetic unit hydrograph using regionalized parameters assuming the basin as an ungauged basin, with the unit hydrograph derived from the observations showed that the model predicted unit hydrograph was more suitable than that obtained by Snyder’s method for Sri Lankan up country basins. Thus, the present model is a useful tool to obtain direct runoff hydrograph for ungauged basins. 相似文献
11.
基于Dyna-CLUE改进模型和SD模型耦合的山区城镇用地情景模拟研究——以岷江上游地区为例 总被引：3，自引：0，他引：3
山区城镇扩张受山区地形和山地灾害等因素限制,而常用的土地利用模型难以有效表达这一特征。本文通过对Dyna-CLUE（Dynamic Conversion of Land Use and its Effects Model）模型进行改进并结合系统动力学（System Dynamic,SD）模型,充分发挥这2个模型在微观土地分配,及宏观情景模拟上的优势,很好地表达了山区地形和山地灾害等因素对山区城镇扩张的限制作用,为山区城镇扩张情景模拟提供了一个有效的方法。以岷江上游地区为例,根据研究区历史统计数据构建山区城镇用地SD模型,模拟低速发展、惯性发展和高速发展3种不同发展情景下城镇用地的需求,结合Dyna-CLUE改进模型,预测了对应情景下2011-2030年的城镇用地范围,并探究其对其他土地利用类型的影响。结果表明,发展速度越快,城镇主体越快达到地理限制区域的上限,并开始沿山间平地向两端扩张。耕地受山区城镇扩张的影响要远远超出其他土地利用类型,离城镇越近受影响越大。随着城镇扩张的加剧,其对自然环境的影响也逐渐增大。模型模拟结果能为山区城镇用地规划、评估由城镇扩张造成的生态环境问题和制定相应的对策提供有效的技术支撑。 相似文献
12.
LIU Chun-la ;CHEN Ming-xing ;TANG Zhi-peng ;LIU Wei-dong ;LU Da-dao ;ZHANG Yi-feng 《山地科学学报》2014,11(5):1372-1382
A case study is presented of a regional development model for valley economies in the mountain areas of Beijing, China. The nature and framework of the valley economy model are described and the development of the model, which is specific to the mountain areas of Beijing, is analyzed. Five different valley economy models applied in the Beijing mountain areas are compared. The major purpose of the valley economy model is to develop the regional economy, including the selection of appropriate industries, the allocation of industrial space, the establishment of supply chains and the integration of various industries. Pilot experiments using the valley economy model have been conducted in seven counties（districts） in Beijing： Pinggu, Huairou, Changping, Mentougou, and Fangshan districts, and Yanqing and Miyun counties. Five models for developing the Beijing mountain areas have been explored, including： creative cultural industries, characteristic industry clusters, the promotion of large tourist areas, natural scenic tourism and folk cultural tourism. Each model has its own unique features and potential to help in the regional development of mountain areas. 相似文献
13.
多尺度DEM提取地势起伏度的对比分析——以福建低山丘陵区为例 总被引：4，自引：0，他引：4
坡度和起伏度是地形描述中最常用的参数,它们能快速、直观地反映地势起伏特征;坡度是划分平原和非平原的重要依据之一,地势起伏度可进一步划分台地、丘陵、小起伏山地、中起伏山地和大起伏山地等类型,基本地貌类型就是由海拔和起伏度两个指标确定的形态类型,它是遥感解译划分更详细地貌类型的基础。本研究以福建省1∶25万和1∶10万的DEM为实验数据,计算坡度划分平原和山地大区,其临界坡度值约为3°;利用ArcG IS空间分析中栅格窗口递增方法,对应不同尺度的DEM,计算地势起伏度,确定研究区的最佳分析窗口面积为4.41km2,得出中国低山丘陵区计算基本地貌形态类型的最佳尺度DEM为1∶25万比例尺,而1∶10万比例尺DEM适用于没有连绵起伏的更小范围的低山丘陵区;利用已有研究成果得出不同尺度DEM计算地势起伏度与最佳格网单元之间的函数关系。该研究对提取我国低山丘陵区基本地貌形态类型具有一定的借鉴作用。 相似文献
14.
The precision modeling of dam break floods can lead to formulation of proper emergency action plan to minimize flood impacts within the economic lifetime of the assets.Application of GIS techniques in integration with hydrological modeling for mapping of the flood inundated areas can play a momentous role in further minimizing the risk and likely damages.In the present study,dam break analysis using DAMBRK model was performed under various likely scenarios.Probable Maximum Flood (PMF)calculated for a return period of 1000 years using deterministic approach was adopted for dam break analysis of the proposed dam under various combinations of breach dimensions.The available downstream river cross-sections data sets were used as input in the model to generate the downstream flood profile.Dam break flow depths generated by the DAMBRK model under various combinations of structural failure are subsequently plotted on Digital Elevation Model(DEM)of the downstream of dam site to map the likely affected area.The simulation results reveals that in one particular case the flood without dam may be more intense if a rainfall of significant intensity takes place. 相似文献
15.
洪水研究包括径流与淹没两种模式。为了探究流域降雨产汇流与淹没情况、提高洪水预报精度,本研究在传统流域水文模型的基础上耦合二维水动力学模型,建立水文-水动力耦合模型。以我国吉林温德河流域为研究实例,模拟了2017年“7·13”洪水在下游口前镇所处子流域洪水淹没过程。首先对基础数据进行预处理,建立HEC-HMS水文模型并进行参数优化后,最终获得流量过程水文结果作为水动力学模型边界条件,之后建立HEC-RAS二维水动力学模型对重要子流域进行淹没模拟。耦合模型计算结果显示,水文模型经多参数优化流量模拟的NSE系数为0.988,水动力计算最大淹没水深达9.3 m相对误差为-5.2%。从泛洪模拟结果来看,子流域上游部分的农田大量被淹,淹没水深范围在0.5~2.0 m,平均流速基本在1 m/s以下。下游口前镇内最大淹没水深接近1 m,水流速度0.2 m/s至1.5 m/s,与实际的淹没情况相吻合。研究表明,所建水文水动力耦合模型模拟计算的结果准确率较高,对具有复杂水文、水力条件的流域的洪水预报具有重要的指导意义。 相似文献
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本文采用信息量模型法研究湖南省山丘区小流域山洪灾害的危险性程度。信息量模型的最大意义是能从影响山洪灾害发生的众多因素中找到“最佳因素组合”。基于湖南省1955-2015年近60年的历史山洪灾害数据,结合地形、下垫面以及降雨条件,利用信息量模型按危险性程度高低划分出湖南省山丘区山洪灾害危险性的分布情况。研究结果表明,湖南省山丘区山洪灾害容易发生在坡度小于10°,高程小于100 m,起伏度小于30 m,土地覆被为人工表面,土壤类型为粘土以及降雨量在1584.3~1662.0 mm之间的区域。湖南省山丘区危险等级较高的地级市有永州市、郴州市、株洲市、岳阳市、娄底市以及长沙东部山区,经过混淆矩阵验证后,通过信息量方法建立的山洪灾害危险性评价模型准确率为75.36%,基本可信。 相似文献
18.
Glacial lake outburst floods(GLOFs)represent one of the most serious hazard and risk in deglaciating high mountain regions worldwide and the need for GLOF hazard and risk assessment is apparent.As a consequence,numerous region-and nation-wide GLOF assessment studies have been published recently.These studies cover large areas and consider hundreds to thousands of lakes,prioritizing the hazard posed by them.Clearly,certain simplification is required for executing such studies,often resulting in neglecting qualitative characteristics which would need manual assignment.Different lake dam types(e.g.,bedrock-dammed,moraine-dammed)are often not distinguished,despite they control GLOF mechanism(dam overtopping/dam breach)and thus GLOF magnitude.In this study,we explore the potential of easily measurable quantitative characteristics and four ratios to approximate the lake dam type.Our dataset of 851 lakes of the Cordillera Blanca suggests that while variances and means of these characteristics of individual lake types differ significantly(F-test,t-test),value distribution of different geometrical properties can’t be used for the originally proposed purpose along the spectra.The only promising results are obtained for extreme values(selected bins)of the ratios.For instance,the low width to length ratio indicates likely morainedammed lake while the high value of ratio indicating round-shape of the lake indicates increased likelihood of bedrock-dammed lake.Overall,we report a negative result of our experiment since there are negligible differences of relative frequencies in most of the bins along the spectra. 相似文献
19.
将深度全连接神经网络引入大坝变形预测领域,结合大坝多源监测数据的训练样本,建立基于深度全连接神经网络的大坝变形预测模型。利用几种常见的深度优化学习算法对模型进行优化训练,通过对比各损失函数的变化曲线选取最优学习算法,进一步构建基于最优学习算法的深度全连接神经网络大坝变形预测模型;最后结合大坝多源监测数据的测试样本对模型进行检验分析,并将预测结果和传统BP神经网络的预测结果进行对比。研究结果表明,本文的深度全连接神经网络模型预测精度高、实用性强,可为大坝安全监控提供参考。 相似文献
20.
山地因其较高的异质性和特殊的环境特征给遥感科学及其应用带来了诸多问题和挑战。为实现山地植被信息的精准提取,本研究选择部分滇西北山地区域作为研究区开展方法实验,利用高分辨率遥感影像数据和数字高程模型,结合分区分层感知思想,提出一种基于不确定性理论的山地植被型组分类制图方法。首先结合地形对研究区影像进行多尺度分割制作图斑;然后根据图斑特征使用随机森林方法进行分类,将分类结果与对应类别样本间的相似性作为优化目标, 并构建混合熵模型定量计算图斑推测类型的不确定性,据此进行针对性的样本补充和分类模型的迭代优化。实验总体分类精度达90.8%,较迭代前提升了29.4%,Kappa系数达到0.875。在高不确定性区域,该方法相比使用一次性补样和随机补样方法的分类结果,精度分别提高了17%和13%。研究结果表明,通过人机交互的方式,基于不确定性理论为样本库融入增量信息的迭代优化方法能够有效提高植被型组分类的精度,相较于传统的样本选择方法具有更高的效率和更低的不确定性。 相似文献