The distribution of sewage discharge outlets will effect on the river assimilative capacity to certain extent. There are different calculation formulas of assimilative capacity for various the positions of the outlets. As for the small- and middle-sized rivers, based on one—dimension assimilative model, the recursion formula for assimilative capacity calculation can be obtained by stepwise deduction under the condition of the uniform pollution source set into river. Considering the runoff dilution and purification in the calculated reach, this formula is effective for assimilative capacity calculation under the condition of the simultaneous action from point/area uniform pollution sources and reach runoff. At the same time, a study was made on the influence of piece-wise node n and reach runoff q in the recursion formula on the pollutant capacity calculation results, so as to suggest the normal principle for the value of n.%排污口分布对于河道纳污能力有一定影响,设定的排放位置不同,纳污能力计算公式亦不同.针对中小型河道,从一维纳污能力模型的基本型式出发,通过分段推演得出均匀污染源入河设定下河道纳污能力计算的递推公式.该公式综合考虑了计算河段内沿程径流变化的稀释和自净作用,简洁实用,可以有效解决点、面均匀污染源和区间径流同时作用下的纳污能力计算问题.同时研究分析了递推公式中分段节点数n和区间径流q对纳污能力计算结果的影响,并建议n取值的一般原则.研究成果可作为现行一维纳污能力计算方法的补充或参考.
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