水库倾斜岸坡地形污染混合区的三维解析计算方法

3D Analytic Computational Method of Pollutant Mixing Zone for Reservoir with Incline Bank

在恒定时间连续点源条件下,从移流扩散方程的简化三维解析解出发,对水库倾斜岸坡地形污染混合区的三维解析计算方法进行了探讨和理论求解,推导了污染混合区长度、最大宽度、最大深度、相应纵坐标和面积以及最大允许污染负荷量的解析计算公式,进行了污染混合区解析计算公式的分析与讨论。结果表明,水库倾斜岸坡地形污染混合区解析计算公式与等标污染负荷、流速、角域映射系数以及岸边混合扩散特性等因素有关,可以作为水库排污口污染混合区允许范围的计算依据,也可以根据水质目标浓度与背景浓度之差,以及污染混合区允许长度或面积或宽度计算最大允许污染负荷量。给出了非保守物质污染混合区长度的计算公式和忽略反应降解作用按保守物质处理的条件:降解数≤0.054。

Under the condition of continuous point source in a constant time, and starting from the simplified 3D analytic solution of the advection-diffusion equation, this paper discusses the 3D analytic computational method for the pollutant mixing zone and has obtained the theoretical solution for a reservoir with incline bank, and the analytic computational formulas for the pollutant mixing zone＇s length, maximum width, maximum depth and its yoordinate, area and the maximum allowable amount of pollution. The results show that the analytic computational method for the reservoir with incline bank pollutant mixing zone takes account some important factors, such as equivalent pollution load, flow velocity, correction coefficient of comer field mapping, and shoreside mixing and diffusion characteristics, and it can be used as a basis in calculating pollutant mixing zone near the reservoir sewage outlet within the allowed range, and the nlaximum allowable amount of pollution according to the difference between water quality targetand background concentration, and the allowable length, area or width of the pollutant mixing zone. The paper gives the calculation formula for the length of non-conservative substances pollutant mixing zone and the condition under which the reaction and decay effect may be neglected, and pollutant may be treated as conservative substance. The condition expressed in decay number is≤0.054.