Taking into account the heavy pollutant load and huge environmental water demand of urban river system in Bao'an district, an approach of using the reclaimed water from sewage plants as compensatory environmental water of urban rivers was analyzed. One dimension steady and un-steady water quality models were employed to calculate the environmental water demand of ten local rivers under four reclaimed water supply conditions respectively. From the respect of keeping the balance between river environmental water demand and supply, the average reclaimed water quality was put forward. Moreover, the relationship between environmental water demand and the reclaimed water quality was quantitatively analyzed. Furthermore, allocation of reclaimed water was also discussed on the basis of the spatial distribution of urban rivers and the sewage plants planning. The results showed that, environmental water demand of Maozhou and Guanlan River was the most, which was taking more than 60% of the total environmental water demand of local urban rivers. For the sake of keeping the balance between river environmental water demand and reclaimed water, the average reclaimed water quality should be BOE5 =6.0 mg/L. Under the same pollutant load condition, environmental water demand approximately exponentially reduced corresponding to the linear improvement of reclaimed water quality. By optimally allocating the reclaimed water, it could meet the total environmental water demand of local urban rivers. The allocating result could be regarded as a reference of sewage plant designing.%以深圳市宝安区为例,探讨以再生水满足城市水系环境需水的方法.应用一维恒定与非恒定水质模型计算了4种补水水质方案下该区10条主要河流的环境需水量,从水量平衡角度提出全区再生水BOD5的平均值,并进一步分析了补水水质与河流环境需水量的关系.结合该区水系与污水处理系统空间位置,提出3种再生水的空间配置方法.结果表明:茅洲河和观澜河的环境需水量较大,占全区河流环境需水总量的60％以上；全区再生水BOD5平均值为6.0 mg/L;在污染负荷不变的条件下,河流环境需水量随补水水质的线性提高呈近似指数型减少；3种再生水配置方法均可利用该区的再生水来满足河流环境需水量要求,优化配置结果可为污水处理厂设计提供参考.
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