Study of discontinuities in hydrological data using catastrophe theory     

Mohammad Ali Ghorbani  Rahman Khatibi  Loren Cobb 《水文科学杂志》2013,58(7):1137-1151

Abstract

Modelling and prediction of hydrological processes (e.g. rainfall–runoff) can be influenced by discontinuities in observed data, and one particular case may arise when the time scale (i.e. resolution) is coarse (e.g. monthly). This study investigates the application of catastrophe theory to examine its suitability to identify possible discontinuities in the rainfall–runoff process. A stochastic cusp catastrophe model is used to study possible discontinuities in the monthly rainfall–runoff process at the Aji River basin in Azerbaijan, Iran. Monthly-averaged rainfall and flow data observed over a period of 20 years (1981–2000) are analysed using the Cuspfit program. In this model, rainfall serves as a control variable and runoff as a behavioural variable. The performance of this model is evaluated using four measures: correlation coefficient, log-likelihood, Akaike information criterion (AIC) and Bayesian information criterion (BIC). The results indicate the presence of discontinuities in the rainfall–runoff process, with a significant sudden jump in flow (cusp signal) when rainfall reaches a threshold value. The performance of the model is also found to be better than that of linear and logistic models. The present results, though preliminary, are promising in the sense that catastrophe theory can play a possible role in the study of hydrological systems and processes, especially when the data are noisy.

Citation Ghorbani, M. A., Khatibi, R., Sivakumar, B. & Cobb, L. (2010) Study of discontinuities in hydrological data using catastrophe theory. Hydrol. Sci. J. 55(7), 1137–1151.  相似文献   

A spatially distributed Clark’s unit hydrograph based hybrid hydrologic model (Distributed-Clark)     

Younghyun Cho  Venkatesh M. Merwade 《水文科学杂志》2013,58(10):1519-1539

ABSTRACT

A hybrid hydrologic model (Distributed-Clark), which is a lumped conceptual and distributed feature model, was developed based on the combined concept of Clark’s unit hydrograph and its spatial decomposition methods, incorporating refined spatially variable flow dynamics to implement hydrological simulation for spatially distributed rainfall–runoff flow. In Distributed-Clark, the Soil Conservation Service (SCS) curve number method is utilized to estimate spatially distributed runoff depth and a set of separated unit hydrographs is used for runoff routing to obtain a direct runoff flow hydrograph. Case studies (four watersheds in the central part of the USA) using spatially distributed (Thiessen polygon-based) rainfall data of storm events were used to evaluate the model performance. Results demonstrate relatively good fit to observed streamflow, with a Nash-Sutcliffe efficiency (E_NS) of 0.84 and coefficient of determination (R²) of 0.86, as well as a better fit in comparison with outputs of spatially averaged rainfall data simulations for two models including HEC-HMS.  相似文献   

Incorporating groundwater recharge and discharge functions into an existing monthly rainfall–runoff model/Incorporation de fonctions de recharge et de vidange superficielle de nappes au sein d’un modèle pluie-débit mensuel existant     

《水文科学杂志》2013,58(2)

Abstract

Abstract There is an urgent need for an integrated surface water and groundwater modelling tool that is suitable for southern African conditions and can be applied at various basin scales for broad strategic water resource planning purposes. The paper describes two new components (recharge and groundwater discharge) that have been added to an existing monthly time-step rainfall–runoff model that is widely used in the southern African subcontinent. The new components are relatively simple, consistent with the existing model formulation, but based on accepted groundwater flow principles and well understood groundwater parameters. The application of the revised model on two basins in southern Africa with quite different baseflow characteristics has demonstrated that the new components have a great deal of potential, even if the improvement is only to be able to simulate the groundwater baseflow component of total runoff more explicitly. More comprehensive testing and comparison of the results with existing groundwater and geohydrological data is required, while some extensions to the new components need to be considered to ensure that the model can be considered applicable to a wide range of basin and climate types.  相似文献   

Controls on Devonian–Carboniferous magmatism in Tasmania,based on inherited zircon age patterns,Sr, Nd and Pb isotopes,and major and trace element geochemistry     

L. P. Black  J. L. Everard  M. P. McClenaghan  C. R. Calver  A. M. Fioretti 《Australian Journal of Earth Sciences》2013,60(7):933-968

Devonian–Carboniferous granites are widespread in Tasmania. In eastern Tasmania, Devonian granites intrude Ordovician–Early Devonian quartz-rich turbidites of the Mathinna Supergroup. The earliest (～400 Ma) I-type granodiorites may be arc-related. Following the Tabberabberan Orogeny (～389 Ma), more felsic and, finally, strongly fractionated I- and S-type granites were emplaced until ～373 Ma. In contrast, western Tasmania granites intrude a more diverse terrane of predominantly marine shelf successions, with depositional ages as old as Late Mesoproterozoic. They are mostly felsic and fractionated I- and S-types emplaced from ～374–351 Ma, possibly in response to post-collisional crustal extension following juxtaposition of the eastern and western Tasmanian terranes. Granites from the two terranes are readily distinguishable by the age spectra of their inherited zircon, which are noticeably similar to those of the detrital zircon from sedimentary successions in their respective terranes. Furthermore, within each terrane, both I and S-types yield similar inheritance patterns. This suggests a pivotal role for the sedimentary successions in the petrogenesis of both types. Western Tasmanian granites are also enriched in ～1600 Ma zircon, which is essentially unrepresented in the exposed supracrustal succession. Subtle differences between the inheritance and detrital age spectra in eastern Tasmania probably relate to unrepresentative sampling of the supracrustal rocks. Nd, Sr and Pb isotopic characteristics of the granites are consistent with their derivation by mixing of magmas derived from the mantle, possibly the lower crust, and from supracrustal rocks. Systematic isotopic trends in some eastern Tasmanian I-types, particularly in the Scottsdale Batholith, correlate well with major and trace element geochemistry and age. The isotopes are inconsistent with simple restite unmixing or crystal fractionation in a closed magma chamber, and indicate progressive contamination by the Mathinna Supergroup, or similar rocks. The isotopic characteristics of late, strongly fractionated granites, although sometimes obscured by hydrothermal alteration, are also consistent with concurrent assimilation-fractional crystallisation processes. Together with the close association of some strongly fractionated I- and S-types, this suggests that such granites were generated directly in the lower crust, and were not derived from unfractionated parental granite magmas.  相似文献   

青岛台站重力固体潮和海潮负荷特征研究   总被引：1，自引：0，他引：1  

杜文成  袁林果  张宁宁  杨忠荣  姜中山 《大地测量与地球动力学》2018,38(9):913-916

选取青岛台站2012-01~2013-02 gPhone重力仪连续观测资料进行预处理和调和分析，获得其重力潮汐参数，并选取8个全球海潮模型对O1、K1和M2潮波进行海潮负荷改正。结果表明：1）8个主要潮波调和分析的振幅因子标准差均在2.6%之内，与理论潮汐模型值的差异也在3.0%之内；2）利用海潮模型对O1、K1和M2潮波进行改正能有效地降低残差矢量，观测残差负荷改正的有效性大致分布在30%~75%，全球海潮模型对青岛台站主要潮波的海潮负荷改正差别不大。  相似文献   

海洋碳汇经济价值核算研究   总被引：1，自引：0，他引：1  

刘芳明  刘大海  郭贞利 《海洋通报》2019,38(1):8-13

海洋碳汇经济价值核算是推动海洋碳汇市场交易、促进海洋环境保护和生态修复的前提和基础。本文探讨了海洋碳汇及海洋碳汇价值内涵，提出海洋碳汇经济价值分狭义与广义两种，重点分析了广义海洋碳汇价值的特点和构成，运用“总经 济价值法”核算广义海洋碳汇价值，构建了分类价值指标体系和分类核算方法。最后从海洋碳汇资源调查监测方法学、评估与核算标准体系、海洋增汇项目开发、海洋碳汇政策保障等角度提出海洋碳汇发展的具体建议。  相似文献   

Data-moderate assessments of Cape monkfish Lophius vomerinus and west coast sole Austroglossus microlepis in Namibian waters     

JN Kathena  A Kokkalis  MW Pedersen  JE Beyer  UH Thygesen 《African Journal of Marine Science》2018,40(3):293-302

There is global interest in providing scientific advice on optimal harvesting of all commercially exploited fish stocks. Nevertheless, many commercially important stocks lack analytical assessments. Therefore, we evaluate a data-moderate stock assessment method: the stochastic surplus production model in continuous time (SPiCT). The method was applied to two Namibian stocks: (i) the data-rich Cape monkfish Lophius vomerinus, where results are compared to a new data-rich assessment using a state–space assessment model (SAM); and (ii) the data-moderate west coast sole Austroglossus microlepis, which is an important bycatch species in the Cape monkfish fishery, but currently unassessed. The information available to the data-moderate assessment is total commercial catch, commercial catch per unit effort (CPUE), and survey CPUE. SPiCT and SAM gave largely consistent estimates of relative fishing mortality (F/F_MSY) and relative exploitable biomass (B/B_MSY) for the Cape monkfish stock, although with some discrepancies. Differences in the biomass estimates between the two assessments suggest that further investigation is required to understand the cause, and that some caution is necessary when considering the biomass of the stock. SPiCT shows that the west coast sole may be overexploited, although the confidence bounds were too wide for a firm conclusion. Similarity in the estimates of F/F_MSY for Cape monkfish in recent years, using SPiCT relative to SAM, likewise indicates the suitability of SPiCT for managing west coast sole.  相似文献   

海洋激光雷达反演水体光学参数   总被引：2，自引：2，他引：0  

刘志鹏  刘东  徐沛拓  吴兰  周雨迪  韩冰  刘群  宋庆君  毛志华  张与鹏  崔晓宇  陈鹏 《遥感学报》2019,23(5):944-951

研制了一套船载海洋激光雷达,用于探测海水光学参数垂直廓线。2017年8月,该系统在黄海海域进行了实验测量。在准单次散射模型中引入原位测量的光学参数,实现了理想激光雷达回波信号的模拟,并将该理想信号与系统响应函数卷积后精确复现了实验的激光雷达信号。采用Fernald后向迭代积分法(简称Fernald法),比较了不同水体悬浮物激光雷达比下反演的激光雷达衰减系数α与原位漫射衰减系数Kd的差别。基于停航时标定的水体悬浮物激光雷达比,采用Fernald法获得了走航时的激光雷达衰减系数。进一步地,提出一种基于米散射激光雷达数据和原位测量的后向散射数据的融合算法,模拟了高光谱分辨率激光雷达(HSRL)反演α的过程,并将其与Fernald法进行了比较。实验结果表明,自研的海洋激光雷达能够有效探测海水光学参数,基于合适的水体悬浮物激光雷达比的Fernald法可以有效应用于米散射激光雷达的反演,未来无需假设的HSRL在海水光学参数探测领域具有更大的优势。  相似文献   

虚拟海洋场景构建与技术研究     

郭雪  姜晓轶  康林冲 《海洋通报》2018,(6):625-632

随着传统GIS应用向三维立体方向发展,三维虚拟场景在信息认知、空间规划管理、时空挖掘与分析等方面的应用逐渐成为研究热点。本文基于Skyline平台集成遥感影像数据、地形数据、纹理特征数据、倾斜摄影测量数据、三维全景数据和三维模型数据,构建了集虚拟海岛海岸带模型、虚拟海底地形模型和虚拟水体模型于一体的虚拟海洋场景,并针对场景构建中涉及的多源影像数据集成技术、多尺度影像实时切片技术和基于OGC服务的数据集成技术开展了研究。构建形成的虚拟海洋场景在海洋应用服务系统中开展了实践应用。  相似文献   

基于LZW的海底声学探测数据压缩方法研究     

晋松  裴彦良  阚光明  吴爱平  付青青 《海洋科学》2019,43(4):36-45

针对海底声学探测仪器采集数据量大而存储容量有限、数据传输带宽不足的实际问题,基于Lempel-Ziv-Welch(LZW)无损压缩算法,研究海底声学探测数据的实时压缩方法,提高数据压缩效果、节省传输带宽。并在LZW无损压缩算法的基础上结合数据存储的特点对压缩结果进行内存重新分配,极大提高压缩比(压缩数据大小/原始数据大小)。利用海底地震仪(OBS)采集的原始声学探测数据进行测试验证,结果表明该方法对于OBS声学探测数据有很好的压缩比,可用于对OBS采集的声学探测数据进行压缩处理,对于海底探测仪器的研发有很好的指导意义。  相似文献