标题 | 确定河渠纵向离散系数的分位数回归法 |
范文 | 杨双等 摘要:采用分位数回归的纵向离散系数研究方法和双站点浓度时间数据,对突发水污染事故中河渠的水质进行预测,并对比分析了分位数回归与最小二乘法回归效果。实例研究结果显示,运用分位数回归法确定河渠纵向离散系数效果好,第一站点的回归参数通过了97.5%置信水平下的假设检验,第二站点的预测值与实际值相关系数最高达到了0.928。同时,分位数回归法在解决偏态分布问题时较最小二乘法有明显优势。 关键词:突发水污染;纵向离散系数;偏态分布;示踪试验;分位数回归;R软件 中图分类号:TV131.2;X143 文献标志码:A 文章编号: 16721683(2014)05006304 Quantile regression method to determine longitudinal dispersion coefficient of river channel YANG Shuang, YANG Haidong, WANG Zhuomin, XIAO Yi, SHAO Dongguo (State Key laboratory of Water Resources and Hydropower Engineering Science, Wuhan University,Wuhan 430072,China) Abstract:The determination method of longitudinal dispersion coefficient based on the quantile regression and the concentrationtime data of two sites were used to predict the water quality in the river channel.Moreover,the results determined by the quantile regression and least squares regression methods were compared.The example results showed that the quantile regression method is feasible and effective to determine the longitudinal dispersion coefficient of river channel.The quantile regression parameters passed the hypothesis test in the 97.5% confidence level at the first site,and the highest correlation coefficient of the predicted and actual values at the second site reached up to 0.928.In addition,quantile regression method has more advantage in solving the problems with skewed distribution than the least squares regression method. Key words:sudden water pollution;longitudinal dispersion coefficient;skewed distribution; tracer experiment;quantile regression;R software 南水北调中线总干渠上桥梁等水工建筑物众多,存在发生突发水污染事故的风险。水污染事故发生时需要对渠道水质进行快速预测,并提出应急处置对策[12]。为了反映污染物在水流中运动的基本特征,人们在水流的流动状态稳定、均匀,且污染物的分布只随污染源变化等假设条件的基础上建立了很多水质模型[3]。在这些水质模型的应用过程中,确定纵向离散系数是一个关键工作,也是环境和流体力学领域研究的热点[45]。 目前有关纵向离散系数的确定方法中,理论公式法和经验公式法都有相当严格的适用条件,示踪试验方法则能够较准确地拟定河渠的纵向离散系数[6],但对浓度随时间偏态分布的情况适用性不好。根据瞬时点源一维水质模型,污染物迁移扩散属于高斯正态分布,而I.Guymer[7]通过大量试验研究发现,天然河流或不规则断面渠道中瞬时点源污染物的迁移扩散呈现正偏态分布。南水北调中线渠道明渠段以梯形断面为主,但是也存在弯道段、倒虹吸、渡槽和渐变段,沿程断面形状不规则,因此其污染物迁移扩散规律应为偏态分布。另外,最小二乘法过分注重整体拟合效果,使得其拟合后污染物重心和峰值往往偏离实际情况较远;优化类算法只需一个断面的时间浓度过程数据,无法避免初始段未均匀混合的影响,如非线性逼近法、单纯形加速法、相关系数极值法和快速SA法[810]。可见,现有方法研究沿程断面不规则的河渠污染物扩散偏态分布问题时,无法准确确定污染团峰值大小、重心位置等信息,因此亟待提出一种能够解决这种问题的新方法。 就拟合效果而言,如果示踪剂浓度随时间变化符合正态分布,则可以直接运用中位数回归或最小二乘法对第一站点的拟合参数值进行预测;如果浓度随时间变化为偏态分布,则分位数回归能够提供更加准确的信息。因此,分位数回归相比最小二乘法回归具有明显优势。 [BT2][STHZ]4 结语 本文提出了基于分位数回归的河渠纵向离散系数研究方法,并在R软件中进行了算例应用,结果显示,第一站点处各分位数回归参数结果通过了975%置信水平下的假设检验,第二站点处预测值与实际值相关系数最高达到了0928。通过对比,发现中位数回归参数结果可以近似代替最小二乘法回归结果,且在浓度随时间偏态分布的情况下,分位数回归更具优势,充分地显示了其优越性。分位数回归方法利用双站点浓度时间数据确定纵向离散系数,减弱了初始段未均匀混合过程对预测效果的影响,解决了目前研究方法在研究沿程断面不规则的河渠纵向离散系数中,无法准确提供污染团峰值大小、重心位置的问题。 分位数回归结果具有很好的稳健性,能够为研究者提供丰富的信息,在解决偏态分布问题时优点尤为突出。因此分位数回归方法的应用为纵向离散系数研究领域以及水文水资源其他方向的研究提供了一个新思路。 参考文献(References): [1] 曹倩,邵东国,张 华,等.梯形断面明渠纵向离散系数的分析[J].南水北调与水利科技,2012,10(6):1417.(CAO Qian,SHAO Dongguo,ZHANG Hua,et al.Determination of longitudinal dispersion coefficient of trapezoidal open channels[J].SouthtoNorth Water Transfers and Water Science & Technology,2012,10(6):1417.(in Chinese)) [2] SHAO Dongguo,YANG Haidong,XIAO Yi,et al.Water quality model parameter identification of an open channel in a long distance water transfer project based on finite difference,difference evolution and Monte Carlo[J].Water Science & Technology,2014,69(3):587594. [3] 程声通.环境系统分析教程[M].北京:化学工业出版社.2006:3638.(CHENG Shengtong.Environmental system analysis tutorial[M].Beijing:Chemical Industry Press.2006:3638.(in Chinese)) [4] Zhang Wei.A 2D numerical simulation study on longitudinal solute transport and longitudinal dispersion coefficient [J].Water Resources Research,2011,47(7). [5] 陈永灿,王志刚,朱德军,等.冰封河道纵向离散系数计算研究[J].水力发电学报,2012,31(5):173177.(CHEN Yongcan,Wang Zhigang,ZHU Dejun,et al.Study on longitudinal dispersion coefficient for icecovered rivers[J].Journal of Hydroelectric Engineering,2012,31(5):173177.(in Chinese)) [6] 高伟,杨中华.弯道纵向离散系数研究进展[J].中国农村水利水电,2009,2:58.(GAO Wei,YANG Zhonghua.Advance in longitudinal dispersion coefficient of river bends[J].China Rural and Hydropower,2009,2:58.(in Chinese)) [7] I Guymer.Longitudinal Dispersion in Sinuous Channels with Changes in Shape[J].Journal of Hydraulic Engineering,1998,124:3340. [8] 顾莉,华祖林.天然河流纵向离散系数确定方法的研究进展[J].水利水电科技进展,2007,27(2):8589.(GU Li,HUA Zulin.Advance in determination of longitudinal dispersion coefficient of natural rivers[J].Advances in Science Technology of Water Resources,2007,27(2):8589.(in Chinese)) [9] 顾莉,华祖林,何 伟,等.河流污染物纵向离散系数确定的演算优化法[J].水利学报,2007,38(12):14211425.(GU Li,HUA Zulin,HE Wei,et al.Routingopimization method for determination of longitudinal dispersion coefficient in river[J].Journal of Hydraulic Engineering,2007,38(12):14211425.(in Chinese))[ZK)] [10] [ZK(#]杨海东,肖 宜,王卓民,等.突发性水污染事件溯源方法[J].水科学进展,2014,25(1):122129.(YANG Haidong,XIAO Yi,WANG Zhuomin,et al.On source identification method for sudden water pollution accidents[J].Advances in Water Science,2014,25(1):122129.(in Chinese)) [11] Roger Koenker,Gilbert Bassett,Jr.Regression Quantiles[J].Econometrica,1978,46(1):3350. [12] 乔舰,李再兴.分位数回归的理论再说明及实例分析[J].统计与决策,2012,19:104107.(QIAO Jian,LI Zaixing.Quantile regression theory to explain and instance analysis[J].Statistics and Decision,2012,19:104107.(in Chinese)) [13] 陈建宝,丁军军.分位数回归技术综述[J].统计与信息论坛,2008,3:8996.(CHEN Jianbao,DING Junjun.A review of technologies on quantile regression[J].Statistics & Information Forum,2008,3:8996.(in Chinese)) [14] Lingxin Hao,Daniel Q Naiman.分位数回归模型[M].肖东亮,译.上海:上海人民出版社,2012.(Lingxin Hao,Daniel Q.Naiman.Quantile regression model[M].XIAO Dongliang,translation.Shanghai:Shanghai People′s Publishing House,2012.) [15] 苏瑜,万宇艳.分位数回归思想与简单应用[J].统计教育,2009(10):5861.(SU Yu,WAN Yuyan.The idea and application of quantile regression[J].Statistical Thinktank,2009(10):5861.(in Chinese)) [16] 温季,郭建青,宰松梅,等.河流水团示踪试验数据分析的双站直线解析法[J].水利学报,2008,39(5):618622.(WEN Ji,GUO Jianqing,ZAI Songmei,et al.Linear analytic method for determining water quality parameters of river according to the observation data obtained from two sections[J].Journal of Hydraulic Engineering,2008,39(5):618622.(in Chinese)) 分位数回归结果具有很好的稳健性,能够为研究者提供丰富的信息,在解决偏态分布问题时优点尤为突出。因此分位数回归方法的应用为纵向离散系数研究领域以及水文水资源其他方向的研究提供了一个新思路。 参考文献(References): [1] 曹倩,邵东国,张 华,等.梯形断面明渠纵向离散系数的分析[J].南水北调与水利科技,2012,10(6):1417.(CAO Qian,SHAO Dongguo,ZHANG Hua,et al.Determination of longitudinal dispersion coefficient of trapezoidal open channels[J].SouthtoNorth Water Transfers and Water Science & Technology,2012,10(6):1417.(in Chinese)) [2] SHAO Dongguo,YANG Haidong,XIAO Yi,et al.Water quality model parameter identification of an open channel in a long distance water transfer project based on finite difference,difference evolution and Monte Carlo[J].Water Science & Technology,2014,69(3):587594. [3] 程声通.环境系统分析教程[M].北京:化学工业出版社.2006:3638.(CHENG Shengtong.Environmental system analysis tutorial[M].Beijing:Chemical Industry Press.2006:3638.(in Chinese)) [4] Zhang Wei.A 2D numerical simulation study on longitudinal solute transport and longitudinal dispersion coefficient [J].Water Resources Research,2011,47(7). [5] 陈永灿,王志刚,朱德军,等.冰封河道纵向离散系数计算研究[J].水力发电学报,2012,31(5):173177.(CHEN Yongcan,Wang Zhigang,ZHU Dejun,et al.Study on longitudinal dispersion coefficient for icecovered rivers[J].Journal of Hydroelectric Engineering,2012,31(5):173177.(in Chinese)) [6] 高伟,杨中华.弯道纵向离散系数研究进展[J].中国农村水利水电,2009,2:58.(GAO Wei,YANG Zhonghua.Advance in longitudinal dispersion coefficient of river bends[J].China Rural and Hydropower,2009,2:58.(in Chinese)) [7] I Guymer.Longitudinal Dispersion in Sinuous Channels with Changes in Shape[J].Journal of Hydraulic Engineering,1998,124:3340. [8] 顾莉,华祖林.天然河流纵向离散系数确定方法的研究进展[J].水利水电科技进展,2007,27(2):8589.(GU Li,HUA Zulin.Advance in determination of longitudinal dispersion coefficient of natural rivers[J].Advances in Science Technology of Water Resources,2007,27(2):8589.(in Chinese)) [9] 顾莉,华祖林,何 伟,等.河流污染物纵向离散系数确定的演算优化法[J].水利学报,2007,38(12):14211425.(GU Li,HUA Zulin,HE Wei,et al.Routingopimization method for determination of longitudinal dispersion coefficient in river[J].Journal of Hydraulic Engineering,2007,38(12):14211425.(in Chinese))[ZK)] [10] [ZK(#]杨海东,肖 宜,王卓民,等.突发性水污染事件溯源方法[J].水科学进展,2014,25(1):122129.(YANG Haidong,XIAO Yi,WANG Zhuomin,et al.On source identification method for sudden water pollution accidents[J].Advances in Water Science,2014,25(1):122129.(in Chinese)) [11] Roger Koenker,Gilbert Bassett,Jr.Regression Quantiles[J].Econometrica,1978,46(1):3350. [12] 乔舰,李再兴.分位数回归的理论再说明及实例分析[J].统计与决策,2012,19:104107.(QIAO Jian,LI Zaixing.Quantile regression theory to explain and instance analysis[J].Statistics and Decision,2012,19:104107.(in Chinese)) [13] 陈建宝,丁军军.分位数回归技术综述[J].统计与信息论坛,2008,3:8996.(CHEN Jianbao,DING Junjun.A review of technologies on quantile regression[J].Statistics & Information Forum,2008,3:8996.(in Chinese)) [14] Lingxin Hao,Daniel Q Naiman.分位数回归模型[M].肖东亮,译.上海:上海人民出版社,2012.(Lingxin Hao,Daniel Q.Naiman.Quantile regression model[M].XIAO Dongliang,translation.Shanghai:Shanghai People′s Publishing House,2012.) [15] 苏瑜,万宇艳.分位数回归思想与简单应用[J].统计教育,2009(10):5861.(SU Yu,WAN Yuyan.The idea and application of quantile regression[J].Statistical Thinktank,2009(10):5861.(in Chinese)) [16] 温季,郭建青,宰松梅,等.河流水团示踪试验数据分析的双站直线解析法[J].水利学报,2008,39(5):618622.(WEN Ji,GUO Jianqing,ZAI Songmei,et al.Linear analytic method for determining water quality parameters of river according to the observation data obtained from two sections[J].Journal of Hydraulic Engineering,2008,39(5):618622.(in Chinese)) 分位数回归结果具有很好的稳健性,能够为研究者提供丰富的信息,在解决偏态分布问题时优点尤为突出。因此分位数回归方法的应用为纵向离散系数研究领域以及水文水资源其他方向的研究提供了一个新思路。 参考文献(References): [1] 曹倩,邵东国,张 华,等.梯形断面明渠纵向离散系数的分析[J].南水北调与水利科技,2012,10(6):1417.(CAO Qian,SHAO Dongguo,ZHANG Hua,et al.Determination of longitudinal dispersion coefficient of trapezoidal open channels[J].SouthtoNorth Water Transfers and Water Science & Technology,2012,10(6):1417.(in Chinese)) [2] SHAO Dongguo,YANG Haidong,XIAO Yi,et al.Water quality model parameter identification of an open channel in a long distance water transfer project based on finite difference,difference evolution and Monte Carlo[J].Water Science & Technology,2014,69(3):587594. [3] 程声通.环境系统分析教程[M].北京:化学工业出版社.2006:3638.(CHENG Shengtong.Environmental system analysis tutorial[M].Beijing:Chemical Industry Press.2006:3638.(in Chinese)) [4] Zhang Wei.A 2D numerical simulation study on longitudinal solute transport and longitudinal dispersion coefficient [J].Water Resources Research,2011,47(7). [5] 陈永灿,王志刚,朱德军,等.冰封河道纵向离散系数计算研究[J].水力发电学报,2012,31(5):173177.(CHEN Yongcan,Wang Zhigang,ZHU Dejun,et al.Study on longitudinal dispersion coefficient for icecovered rivers[J].Journal of Hydroelectric Engineering,2012,31(5):173177.(in Chinese)) [6] 高伟,杨中华.弯道纵向离散系数研究进展[J].中国农村水利水电,2009,2:58.(GAO Wei,YANG Zhonghua.Advance in longitudinal dispersion coefficient of river bends[J].China Rural and Hydropower,2009,2:58.(in Chinese)) [7] I Guymer.Longitudinal Dispersion in Sinuous Channels with Changes in Shape[J].Journal of Hydraulic Engineering,1998,124:3340. [8] 顾莉,华祖林.天然河流纵向离散系数确定方法的研究进展[J].水利水电科技进展,2007,27(2):8589.(GU Li,HUA Zulin.Advance in determination of longitudinal dispersion coefficient of natural rivers[J].Advances in Science Technology of Water Resources,2007,27(2):8589.(in Chinese)) [9] 顾莉,华祖林,何 伟,等.河流污染物纵向离散系数确定的演算优化法[J].水利学报,2007,38(12):14211425.(GU Li,HUA Zulin,HE Wei,et al.Routingopimization method for determination of longitudinal dispersion coefficient in river[J].Journal of Hydraulic Engineering,2007,38(12):14211425.(in Chinese))[ZK)] [10] [ZK(#]杨海东,肖 宜,王卓民,等.突发性水污染事件溯源方法[J].水科学进展,2014,25(1):122129.(YANG Haidong,XIAO Yi,WANG Zhuomin,et al.On source identification method for sudden water pollution accidents[J].Advances in Water Science,2014,25(1):122129.(in Chinese)) [11] Roger Koenker,Gilbert Bassett,Jr.Regression Quantiles[J].Econometrica,1978,46(1):3350. [12] 乔舰,李再兴.分位数回归的理论再说明及实例分析[J].统计与决策,2012,19:104107.(QIAO Jian,LI Zaixing.Quantile regression theory to explain and instance analysis[J].Statistics and Decision,2012,19:104107.(in Chinese)) [13] 陈建宝,丁军军.分位数回归技术综述[J].统计与信息论坛,2008,3:8996.(CHEN Jianbao,DING Junjun.A review of technologies on quantile regression[J].Statistics & Information Forum,2008,3:8996.(in Chinese)) [14] Lingxin Hao,Daniel Q Naiman.分位数回归模型[M].肖东亮,译.上海:上海人民出版社,2012.(Lingxin Hao,Daniel Q.Naiman.Quantile regression model[M].XIAO Dongliang,translation.Shanghai:Shanghai People′s Publishing House,2012.) [15] 苏瑜,万宇艳.分位数回归思想与简单应用[J].统计教育,2009(10):5861.(SU Yu,WAN Yuyan.The idea and application of quantile regression[J].Statistical Thinktank,2009(10):5861.(in Chinese)) [16] 温季,郭建青,宰松梅,等.河流水团示踪试验数据分析的双站直线解析法[J].水利学报,2008,39(5):618622.(WEN Ji,GUO Jianqing,ZAI Songmei,et al.Linear analytic method for determining water quality parameters of river according to the observation data obtained from two sections[J].Journal of Hydraulic Engineering,2008,39(5):618622.(in Chinese)) |
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