Combined analysis of precipitation and water deficit for drought hazard assessment     

Tamara Tokarczyk  Wiwiana Szalińska 《水文科学杂志》2013,58(9):1675-1689

Abstract

The combined analysis of precipitation and water scarcity was done with the use of the Standardized Precipitation Index (SPI) and the Standardized Runoff Index (SRI), developed as a monthly, two-variable SPI-SRI indicator to identify different classes of hydrometeorological conditions. Stochastic analysis of a long-term time series (1966–2005) of monthly SPI-SRI indicator values was performed using a first-order Markov chain model. This provided characteristics of regional features of drought formation, evolution and persistence, as well as tools for statistical long-term drought hazard prediction. The study was carried out on two subbasins of the Odra River (Poland) of different orography and land use: the mountainous Nysa K?odzka basin and the lowland, agricultural Prosna basin. Classification obtained with the SPI-SRI indicator was compared with the output from the NIZOWKA model that provided identification of hydrological drought events including drought duration and deficit volume. Severe and long-duration droughts corresponded to SPI-SRI Class 3 (dry meteorological and dry hydrological), while severe but short-term droughts (lasting less than 30 days) corresponded to SPI-SRI Class 4 (wet meteorological and dry hydrological). The results confirm that, in Poland, meteorologically dry conditions often shift to hydrologically dry conditions within the same month, droughts rarely last longer than 2 months and two separate drought events can be observed within the same year.  相似文献   

A spectral gradient difference based approach for land cover change detection     

《ISPRS Journal of Photogrammetry and Remote Sensing》2013

Change detection with remotely sensed imagery plays an important role in land cover mapping, process analysis and dynamic information services. Euclidean distance, correlation and other mathematic metrics between spectral curves have been used to calculate change magnitude in most change detection methods. However, many pseudo changes would also be detected because of inter-class spectral variance, which remains a significant challenge for operational remote sensing applications. In general, different land cover types have their own spectral curves characterized by typical spectral values and shapes. These spectral values are widely used for designing change detection algorithms. However, the shape of spectral curves has not yet been fully considered. This paper proposes to use spectral gradient difference (SGD) to quantitatively describe the spectral shapes and the differences in shape between two spectra. Change magnitude calculated in the new spectral gradient space is used to detect the change/no-change areas. Then, a chain model is employed to represent the SGD pattern both qualitatively and quantitatively. Finally, the land cover change types are determined by pattern matching with the knowledgebase of reference SGD patterns. The effectiveness of this SGD-based change detection approach was verified by a simulation experiment and a case study of Landsat data. The results indicated that the SGD-based approach was superior to the traditional methods.  相似文献   

基于权马尔可夫链模型的庐江县降水量预测   总被引：1，自引：0，他引：1  

韩璞璞  张生  李畅游  张俊 《水文》2012,32(3):38-42

由于降水过程的随机性与不确定性,使得降水量预测存在一定的难度。对安徽省庐江县1952~2009年逐年降水资料进行了分析,采用样本-标准差分级法将这58年的逐年降水量序列分为枯水年,偏枯水年,平水年,偏丰水年,丰水年5个状态,采用权马尔可夫链模型预测了2010年的降水量,预测结果与实测结果相吻合。  相似文献   

空间分类在连锁超市选址中的应用研究     

杨莉  周志富 《测绘与空间地理信息》2011,34(5):148-151,155

空间数据挖掘是一种知识决策支持技术,本文以大型综合连锁超市为例,研究了空间分类挖掘方法在连锁超市选址预测中的应用问题。结合连锁超市定位理论,对实验数据进行了选择和处理。同时进行了基于关联的分类实验,得到指导和预测选址的知识,并对预测知识的准确性和可信度进行了检验,结果显示预测准确率和可信度较高。本文制定的挖掘方案可为连...  相似文献   

A Comparison of Four Precipitation Distribution Models Used in Daily Stochastic Models     

LIU Yonghe  ZHANG Wanchang  SHAO Yuehong  ZHANG Kexin 《大气科学进展》2011,28(4):809-820

Stochastic weather generators are statistical models that produce random numbers that resemble the observed weather data on which they have been fitted; they are widely used in meteorological and hydrologi- cal simulations. For modeling daily precipitation in weather generators, first-order Markov chain-dependent exponential, gamma, mixed-exponential, and lognormal distributions can be used. To examine the perfor- mance of these four distributions for precipitation simulation, they were fitted to observed data collected at 10 stations in the watershed of Yishu River. The parameters of these models were estimated using a maximum-likelihood technique performed using genetic algorithms. Parameters for each calendar month and the Fourier series describing parameters for the whole year were estimated separately. Bayesian infor- mation criterion, simulated monthly mean, maximum daily value, and variance were tested and compared to evaluate the fitness and performance of these models. The results indicate that the lognormal and mixed-exponential distributions give smaller BICs, but their stochastic simulations have overestimation and underestimation respectively, while the gamma and exponential distributions give larger BICs, but their stochastic simulations produced monthly mean precipitation very well. When these distributions were fitted using Fourier series, they all underestimated the above statistics for the months of June, July and August.  相似文献   

遥感地质勘查技术与应用研究   总被引：14，自引：0，他引：14  

王润生  陈微  杨苏明  张瑞江  葛大庆  张晓坤  张振华  王品清  郭小方  李丽  熊盛青  聂洪峰  梁树能  齐泽荣  杨金中  闫柏琨  赵福岳  范景辉  童立强  林键  甘甫平 《地质学报》2011,85(11):1699-1743

遥感的发展极大地拓宽了人类的视野和视觉能力,以其宏观性、综合性、多尺度、多层次的特点,已成为地质研究和地质勘查不可缺少的技术手段,在地质调查、矿产勘查、地质环境评价、地质灾害监测和基础地质研究等方面都发挥了越来越大的作用.随着传感器分辨率(空间、光谱、时间、辐射)的不断提高,特别是高光谱和干涉雷达技术的发展,不仅极大地...  相似文献   

Middle and late Pleistocene glaciations in the Campo Felice Basin (central Apennines, Italy)   总被引：1，自引：0，他引：1  

Carlo Giraudi  Giulia Bodrato  Nicola Cipriani  Biagio Giaccio 《Quaternary Research》2011,75(1):219-230

The present paper refers to research conducted in the tectonic-karst depression of Campo Felice in the central Apennines (Italy), in which glacial, alluvial and lacustrine sediments have been preserved. Stratigraphic interpretations of sediments underlying the Campo Felice Plain are based on evidence obtained from nine continuous-core boreholes. The boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces. Each cycle is interpreted as an initial response to a mainly warm stage, characterized by low-energy alluvial and colluvial deposition, pedogenesis, and limited episodes of marsh formation. In turn, a mainly cold stage follows during which a lake formed, and glaciers developed and expanded, leading to deposition of glacial and fluvioglacial deposits. The chronological framework is established by eleven accelerator mass spectrometer ¹⁴C ages and three ³⁹Ar-⁴⁰Ar ages on leucites from interbedded tephra layers. These age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2, 3-4, 6, 10 and 14.  相似文献   

基于WebServices的空间信息应用集成解决方案研究     

邬群勇  王钦敏 《地球信息科学学报》2011,13(2):219-225

 在对应用集成及其发展分析的基础上,将Web Services技术运用到空间信息应用集成,提出和建立了面向服务的空间信息应用集成框架,包括Web应用层、服务集成层、服务层和UDDI等4个组成部分。通过该框架,可以实现空间信息集成、服务集成和应用集成。论文解决了空间信息应用集成框架中的2个关键问题:(1)提出了分别从数据层次和业务层次对原有系统集成的解决方案,在数据层次上,提出了基于XML/GML的空间数据封装和基于Web服务接口的空间数据封装策略;在业务层次上,提出根据系统的功能模块和业务逻辑分别进行封装的策略;(2)提出了空间信息Web服务链接和服务组合的串联、并联和混联模式,通过三种模式服务链的设计,可以实现多个服务的链接和组合,从而完成空间信息以及应用集成。  相似文献   

全球链网下的欠发达地区产业集群化研究——以韶关汽车零部件产业为例     

许树辉 《世界地理研究》2011,20(1):36-43

全球链网下的地方产业集群,已成为区域经济发展的重要组织形式。欠发达地区产业集群的形成与发展是特色资源、产业基础、创新文化、政策激励和市场驱动对地方化和全球化两股力量“粘滞—集聚—再粘滞—再集聚”的循环积累结果。针对韶关资源丰富、产业基础厚实,但空间粘滞作用不强、产业集群化程度低的现状,认为韶关汽车零部件产业应走“立足资源,一园三片;精细专工,错位发展”的特色集群化道路。  相似文献   

洞庭湖区的泥沙淤积效应   总被引：7，自引：0，他引：7  

李景保  尹辉  卢承志  毛德华  周和平 《地理学报》2008,63(5):514-523

以1951-2005 年长系列实测泥沙等资料为依据, 从泥沙淤积特性与资源环境之间的关系上, 探讨了洞庭湖区的泥沙淤积效应。研究表明: 由于洞庭湖区始终处于淤积状态, 加之人类活动影响, 导致了泥沙淤积循环演进的格局, 以至于使泥沙的灾害性效应与资源性效应 均在湖区得到充分的显示。主要表现在: ① 塑造了水体滩地、泥沙滩地、湖草滩地、芦苇滩地等类型滩地, 构成了湖泊巨系统的主体; ② 孕育或诱发了泥沙淤积→洲滩扩展、围垦→调洪功能下降、鱼类资源枯竭、生物多样性减少灾害链: 泥沙淤积→洲滩扩展→洪涝、水质污染; 泥沙淤积→植被洲滩浮涨→血吸虫病、害鼠致害灾害链; 泥沙淤积→洪溃决堤→土地沙 化灾害链。这些淤积型泥沙灾害链给湖区直接或间接地造成巨大的经济损失。③ 近55 年间, 泥沙塑造土地约98.13×10⁸hm², 人类合理开发利用洲滩资源获得了巨大的经济效益, 就地挖沙加高防洪大堤2~3 m, 累积土石方约55×10⁸ m³, 节省了购买大量原材料的开支。  相似文献