Data assimilation (4D-VAR) to forecast flood in shallow-waters with sediment erosion     

Eric Blanger  Alain Vincent 《Journal of Hydrology》2005,300(1-4):114-125

In this paper, the four-dimensional variational data assimilation technique (4D-VAR) is presented as a tool to forecast floods. Our study is limited to purely hydrological flows and supposes that the weather, here a big rain, has been already forecasted by meteorological services. The technique consists in minimizing, in the sense of Lagrange, the cost function: a measure of the difference between calculated data and available observations, here the water level. This is done under constraints that are the equations of the physical model. In our case, we modified the shallow-water equations to include a simplified sediment transport model. The steepest descent algorithm is then used to find the minimum. This is made possible because we can compute analytically the gradient of the cost function by using the adjoint equations of the model. As an application of the 4D-VAR technique, the overflowing of the Chicoutimi River at the Chute-Garneau dam, during the 1996 flood, is investigated. It is found that the 4D-VAR method reduces the error in the water height forecast even when the erosion model is not activated. In terms of Lyapunov exponents, we estimate the predictability horizon of such an event to be about half-an-hour after a big rain. However, this limit of predictability can be increased by using more observations or by using a finer computational grid.  相似文献   

Effect of the Mahanadi River on the Development of Storm Surge Along the Orissa Coast of India: A Numerical Study     

S. K. Dube  P. C. Sinha  A. D. Rao  Indu Jain  Neetu Agnihotri 《Pure and Applied Geophysics》2005,162(8-9):1673-1688

River-ocean coupled models are described for the evaluation of the interaction between river discharge and surge development along the Orissa coast of India. The models are used to study the effect of fresh water discharge from the Mahanadi River on the surge response along the Orissa coast due to the October 1999 super cyclone which led to severe flooding of the coastal and delta regions of Orissa. The so-called 1999 Paradip cyclone was one of the most severe cyclones; causing extensive damage to property and loss of lives. The present study emphasizes the impact of the Mahanadi River on overall surge development along the Orissa coast. Therefore, we have developed a location specific fine resolution model for the Orissa coast and coupled it with a one–dimensional river model. The numerical experiments are carried out, both with and without inclusion of fresh water discharge from the river. The bathymetry for the model has been taken from the naval hydrographic charts extending from the south of Orissa to the south of west Bengal. A simple drying scheme has also been included in the model in order to avoid the exposure of land near the coast due to strong negative sea-surface elevations. The simulations with river-ocean coupled models show that the discharge of fresh water carried by the river may modify the surge height in the Bay, especially in the western Bay of Bengal where one of the largest river systems of the east coast of India, the Mahanadi River, joins with the Bay of Bengal. Another dynamic effect of this inlet is the potentially deep inland penetration of the surge originating in the Bay. The model results are in good agreement with the available observations/estimates.  相似文献   

吉林省发展矿泉水产业的战略思考   总被引：1，自引：0，他引：1  

于明宽 《吉林地质》2005,24(1):54-57,88

本文在分析吉林省矿泉水资源特征和矿泉水事业发展现状的基础上，结合国内外矿泉水产业的发展趋势，指出了当前吉林省矿泉水产业发展中存在的问题，提出了快速发展矿泉水产业的对策和建议。  相似文献   

施工降水中的环境保护及水资源合理利用     

钟士国 《岩土工程技术》2005,19(2):101-105

城市缺水是目前带有普遍性的重大问题 ,但在城市建设过程中 ,宝贵的地下水资源遭到浪费的现象又大量存在 ,解决好施工降水与环境保护问题是关系到城市发展的重要问题之一 ,结合郑州市的工程实践 ,谈谈施工降水中的环境保护及水资源合理利用问题。  相似文献   

库水位变化对库岸边坡稳定性的影响   总被引：3，自引：0，他引：3  

夏麾  刘金龙 《岩土工程技术》2005,19(6):292-295

在假定坡体孔隙水水位为水平线且不考虑渗透作用影响的基础上,基于极限平衡法考察了水位上升及下降的快慢对边坡安全系数的影响。对比计算表明:在水位缓慢变化即坡体内外水位线等高的条件下,边坡的安全系数随着水位坡高比的增大先略减小后急剧增大,且在水位坡高比为0.3处取得最小值,在边坡完全淹没于水中时取得最大值。当边坡完全淹没于水中后,水位高于坡顶的多少对边坡安全系数没有影响;在水位骤降或陡升条件下,相同库水位对应的边坡安全系数基本上均小于水位缓慢变化情况下的安全系数,故工程实际中无论是排水还是蓄水,都应尽量保持水位缓慢变化,这样才能使边坡处于较安全的状态。  相似文献   

城市建筑环境--浅谈长沙市中医医院方案设计     

唐琼 《中国勘察设计》2005,(8):32-33

本文以长沙市中医医院的方案设计为例,对如何利用自然环境划分、组织建筑空间以及结合当地人文、地理环境塑造合理的建筑造型进行了详尽的描述。  相似文献   

上海市公共卫生中心空调设计     

寿炜炜  宋静  朱学锦 《中国勘察设计》2005,(8):34-37

介绍了上海市公共卫生中心空调通风的设计特点,突出反映在呼吸道传染病区、呼吸道门诊、呼吸道临检、生物安全实验室的系统设计中,并介绍了空调水系统的特殊要求。  相似文献   

宁东煤田枣泉矿井综合物探效果     

李新安 《中国煤田地质》2005,17(4):50-53

为探明宁东煤田枣泉矿井首采区煤层自然范围及充水性，根据采区内地球物理物征，采用高精度磁法，直流电测深法和激发极化法进行综合勘探。在磁法勘探中结合测区曲线特征，建立数据体模型，正演计算烧变岩边界；电法勘探利用烧变岩含水后电阻率降低的特征确定其含水范围及富水性。  相似文献   

Hydrogeochemistry of karst underground waters at shallow depth in Guiyang City, Guizhou Province     

董志芬  朱立军吴攀沈峥  封志勇 《中国地球化学学报》2005,24(2):194-200

The aim of this study is to shed light on the hydrogeochemical characteristics of karst underground waters at shallow depth in Guiyang City, Guizhou Province with an emphasis on the geochemistry of major elements. Guiyang City bears abundant underground waters and it is also an important representative of the karst areas throughout the world. Ca^2 and Mg^2 are the dominant cations, accounting for 81% -99.7% of the total, and HCO3^- and SO4^2- are the dominant anions. Weathering of limestones and dolostones is the most important factor controlling the hydrogeochemistry of underground waters, and weathering of sulfate and evaporite rocks is less important. Moreover, the precipitation and human activities also have a definite influence on the hydrogeoehemistry of underground waters in the region studied.  相似文献   

虚拟现实和G IS系统集成方法分析   总被引：1，自引：0，他引：1  

付哲  周云轩  刘殿伟  董月娥 《吉林大学学报(地球科学版)》2005,(Z1)

从三个角度论述虚拟现实(V irtua l R ea lity,VR)和地理信息系统(G IS)集成的必要性,通过对集成方法的归纳,提出4种集成方式,并详细介绍了各自的结构体系和具体特征。在此基础上划分了VR与G IS系统集成的4个阶段,分析当前系统集成现状,指出其发展趋势。同时探讨了VR和G IS系统集成中存在的关键问题,包括数据、虚拟景观技术、VRG IS网络化等,给出目前解决这些问题的一些建议和具体途径。  相似文献