基于环境扩散条件的河流宽度分类判别准则  

Criteria for classification of river width based on environmental diffusion conditions

作　　者：武周虎[1] 

机构地区：[1]青岛理工大学环境与市政工程学院,山东青岛266033

出　　处：《水科学进展》2012年第1期53-58,共6页Advances in Water Science

基　　金：国家自然科学基金资助项目(50979036);国家水体污染控制与治理科技重大专项(2009ZX07210-007)~~

摘　　要：在河流排污引起的污染物扩散计算中,不同河流宽度类别对应不同的移流扩散解析解算式,但缺少具体的河流宽度分类判别准则,给实际应用带来很大困难。按照河流污染物扩散受边界反射影响程度的不同,从移流扩散解析解算式的简化条件出发,提出了宽阔、中宽、窄小的分类方法和定义;根据二维可忽略边界反射的条件和达到全断面均匀混合距离小于等于河流宽度的条件,分别求解了河流宽阔与中宽窄小的分区临界关系线和中宽与窄小的分区临界关系线,提出了相应判据的数学表达式;给出了河流宽阔、中宽、窄小的分类判别准则以及各类别河流移流扩散解析解算式的对应关系。最后指出基于环境扩散条件的河流宽阔、中宽、窄小分区是相对的,对于同一河流在不同水力要素、扩散系数、排污强度和允许浓度升高值等条件下,可以得到不同的分区结果。The analytical solution for advection-diffusion equations exists in different forms depending on the solution conditions.The river width class is an important parameter for choosing a solution for calculating the pollutant diffusion rate in rivers due to pollution discharge.However,it would be difficult to implement such a guiding principle in practical applications due to lack of specific criteria for classification of river width.In accordance with the level of river pollutions affected by boundary reflectivity and the result of the consideration of simplified conditions for analytical solutions of advection-diffusion equations,we propose a river width as wide,medium,and narrow three categories.The criteria for classification of river width and the corresponding method of classification are presented.The mathematical expressions for the identification of the three categories are also deduced.The influence of boundary reflection is usually negligible for 2-D river flow and the mixing length in a well-mixed cross section is less or equal to the river width.These conditions are used to solve the advection-diffusion equations for the three categories.The critical dividing line is obtained for separating the wide category from medium and narrow ones.While,the similar line for separating the medium category from the narrow ones is also derived.Finally,it is important to point out that the classified wide,medium,and narrow three categories are relative to each other.Different results could be obtained in the different hydraulic elements,diffusion coefficients,sewage strengths and allowable pollutant concentrations in the same river.

关 键 词：环境水力学 河流 移流扩散 宽度分类 判别准则 

分 类 号：X143[环境科学与工程—环境科学] X522