山丘区小流域沟道洪水演进数值模拟研究
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摘要
近年来,山丘区小流域山洪灾害频发,给当地经济社会造成了严重破坏和影响。为了山洪灾害防治,对山丘区小流域沟道洪水的准确预报预警尤为重要。但因缺乏沟道断面和洪水等基础资料使得山洪演进分析变得非常困难。为此,首先针对山丘区小流域地形数据缺失的问题,基于研究区域的DEM数据概化河道或沟道走向,并依据河道(网)分级理论和稳定河宽概念,提出了两种河宽计算公式的适用性选择指标,以此确定沟道河宽与河槽深度;其次,为了解决沟道因规模小、不规整容易发生漫滩和提高山洪演进中的模拟效率等问题,基于扩散波理论构建并开发了1、2维耦合的山洪模拟模型(1–2D)。为了验证该模型的预测精度和运行效率,以北京房山区漫水河流域作为研究对象,选取了该流域3场典型洪水进行数值模拟并将该1–2D模型的模拟结果与实测资料和2维浅水模型(2D)的模拟结果等进行了对比分析。结果表明:从流量、水位、洪水总量及峰现时间多角度分析,1–2D模型具有较高的模拟精度,模拟成果与2维浅水模型的结果也比较接近,且计算效率更高,适合山丘区小流域沟道洪水的数值模拟分析与预警预报。
In recent years, flashfloods have occurred frequently in the gully regions of small-scale watersheds. They have caused a great deal of damages to the local economy and properties. In order to prevent and control mountainous flashflood disasters, accurately forecasting and early warning of this kind of flashfloods is particularly important. However, it is very difficult to simulate the flashflood evolution in the gully regions because of the lack of controlling cross section information and observed flashflood data in the regions. To overcome these problems, firstly, the generalized orientation of a river or gully was obtained based on the DEM data of the study region. In order to determine the channel width and depth, an applicable selection criterion of two channel width formulas are proposed according to the theory of river network classification and the concept of stable river width. Secondly, a coupled model of one and two dimensional(1–2 D) flashflood routing was developed based on the theory of diffusive wave to improve the simulation efficiency and to solve the easily overlanding problem due to irregular and small size of the gully.In order to verify the accuracy and efficiency of the coupled 1–2 D model, a case study was conducted at the Manshui river-basin in Fangshan District of Beijing city, and the simulated results of the coupled 1–2 D model were compared with those of the 2 D shallow water model and the observed data. The results indicate that the coupled 1–2 D model has a reasonably high accuracy which is almost the same as that of 2 D shallow water model in the aspects of flashflood discharge, water level, total volume and peak arrival time. In addition, the simulating efficiency of the coupled 1–2 D model is higher than that of 2 D shallow water model, which implies the coupled 1–2 D model is much more suitable for the numerical prediction and early warning of flashfloods than the 2 D shallow water model in small scale watersheds.
In recent years, flashfloods have occurred frequently in the gully regions of small-scale watersheds. They have caused a great deal of damages to the local economy and properties. In order to prevent and control mountainous flashflood disasters, accurately forecasting and early warning of this kind of flashfloods is particularly important. However, it is very difficult to simulate the flashflood evolution in the gully regions because of the lack of controlling cross section information and observed flashflood data in the regions. To overcome these problems, firstly, the generalized orientation of a river or gully was obtained based on the DEM data of the study region. In order to determine the channel width and depth, an applicable selection criterion of two channel width formulas are proposed according to the theory of river network classification and the concept of stable river width. Secondly, a coupled model of one and two dimensional(1–2 D) flashflood routing was developed based on the theory of diffusive wave to improve the simulation efficiency and to solve the easily overlanding problem due to irregular and small size of the gully.In order to verify the accuracy and efficiency of the coupled 1–2 D model, a case study was conducted at the Manshui river-basin in Fangshan District of Beijing city, and the simulated results of the coupled 1–2 D model were compared with those of the 2 D shallow water model and the observed data. The results indicate that the coupled 1–2 D model has a reasonably high accuracy which is almost the same as that of 2 D shallow water model in the aspects of flashflood discharge, water level, total volume and peak arrival time. In addition, the simulating efficiency of the coupled 1–2 D model is higher than that of 2 D shallow water model, which implies the coupled 1–2 D model is much more suitable for the numerical prediction and early warning of flashfloods than the 2 D shallow water model in small scale watersheds.
引文
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[15]Lee K T,Chen N C,Chung Y R.Derivation of variable IUHcorresponding to timevarying rainfall intensity during storms[J].Hydrological Sciences Journal,2008,53(2):323-337.
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[2]Zhang Chi,Zhang Jiahua,Wang Hao.Numerical simulation of flash flood routing based on grid outflow correction method[J].Journal of Hohai University(Natural Sciences),2014,42(2):107-113.[张驰,张家华,王浩.基于网格流出修正法的山洪演进数值模拟[J].河海大学学报(自然科学版),2014,42(2):107-113.]
[3]Finaud-Guyot P,Delenne C,Guinot V,et al.1D-2D coupling for river flow modeling[J].Comptes Rendus Mécanique,2011,339(4):226-234.
[4]Huthoff F,Remo J W F,Pinter N.Hydrodynamic leveebreech and inundation modeling of a levee district along the middle mississippi[C]//World Environmental and Water Resources Congress,Albuquerque:EWRI,2012:1428-1437.
[5]Zhang Dawei,Li Danxun,Chen Zhicong,et al.Coupled oneand two-dimensional hydrodynamic models for leveebreach flood and its application[J].Journal of Hydroelectric Engineering,2010,29(2):149-154.[张大伟,李丹勋,陈稚聪,等.溃堤洪水的一维、二维耦合水动力模型及应用[J].水力发电学报,2010,29(2):149-154.]
[6]Jiang Xiaoming,Li Danxun,Wang Xingkui.Coupled oneand two-dimensional numerical modeling of levee-breachflows using the Godunov method[J].Advances in Water Science,2012,23(2):214-221.[姜晓明,李丹勋,王兴奎.基于黎曼近似解的溃堤洪水一维-二维耦合数学模型[J].水科学进展,2012,23(2):214-221.]
[7]Fu Chengwei,Yuan Ximin,Yang Min.A realtime dynamic coupling model for flood routing and its application to flood risk charting[J].Hydro-Science and Engineering,2013(5):32-38.[付成威,苑希民,杨敏.实时动态耦合模型及其在洪水风险图中的应用[J].水利水运工程学报,2013(5):32-38.]
[8]Chen Wenlong,Song Lixiang,Xing Linghang,et al.A 1D-2Dcoupled mathematical model for numerical simulating of flood routine in flood protected zone[J].Advances in Water Science,2014,25(6):848-855.[陈文龙,宋利祥,邢领航,等.一维-二维耦合的防洪保护区洪水演进数学模型[J].水科学进展,2014,25(6):848-855.]
[9]Yuan Ximin,Xue Wenyu,Feng Guona,et al.A coupled oneand two-dimensional hydrodynamic model for analysis of levee-breach flood and its application[J].Advances in Science and Technology of Water Resources,2016,36(4):53-58.[苑希民,薛文宇,冯国娜,等.溃堤洪水分析的一、二维水动力耦合模型及应用[J].水利水电科技进展,2016,36(4):53-58.]
[10]Chen Junhong,Liu Xiaolong,Wang Gang,et al.An analysis of the levee-breach flood for Ganxi Dyke based on 1D and2D coupled hydrodynamic model[J].China Rural Water and Hydropower,2017(6):43-47.[陈俊鸿,刘小龙,王岗,等.基于一、二维耦合水动力模型的赣西联圩溃堤洪水风险分析[J].中国农村水利水电,2017(6):43-47.]
[11]Wu Binbin,Liu Fengcai,Yu Haijun,et al.Development of flood risk real-time analysis system in flood storage-detention district of Daluze and Ningjinbo[J].China Flood&Drought Management,2017,27(2):16-22.[吴滨滨,刘凤彩,喻海军,等.大陆泽及宁晋泊蓄滞洪区洪水风险实时分析系统研发[J].中国防汛抗旱,2017,27(2):16-22.]
[12]She Yougui.Application of diffusion wave calculation method in Pearl River basin[J].Pearl River,2002(6):17-19.[佘有贵.扩散波演算方法在珠江流域的应用研究[J].人民珠江,2002(6):17-19.]
[13]Liu Wei,Peng Xinde,Zhang Xiaobing.Application of oneand two-dimensional flow numerical simulation in flood control evaluation[J].China Water Transport,2010,10(6):112-113.[刘薇,彭新德,张小兵.一、二维耦合水流数值模拟在防洪评价中的应用[J].中国水运(下半月),2010,10(6):112-113.]
[14]Yang Mingnan,Xu Youpeng,Deng Xiaojun,et al.River system change characteristics of urban central area in plain river network region[J].Bulletin of Soil and Water Conservation,2014,34(5):263-266.[杨明楠,许有鹏,邓晓军,等.平原河网地区城市中心区河流水系变化特征[J].水土保持通报,2014,34(5):263-266.]
[15]Lee K T,Chen N C,Chung Y R.Derivation of variable IUHcorresponding to timevarying rainfall intensity during storms[J].Hydrological Sciences Journal,2008,53(2):323-337.
[16]钱宁,张仁,周志德.河床演变学[M].北京:科学出版社,1987.
[17]Huang Caian,Zhou Jiren,Zhao Xiaodong.Theoretical study of exponent in basic hydraulic geometry relation[J].Journal of Sediment Research,2011(6):55-58.[黄才安,周济人,赵晓冬.基本河相关系指数的理论研究[J].泥沙研究,2011(6):55-58.]