滨江水体生态环境需水量研究

STUDY ON ECO-ENVIRONMENTAL WATER DEMAND FOR WATERFRONT BODY

受外域水体特性及潮汐作用影响，滨江水体生态环境需水复杂多变。以镇江内江为例，分析了不同时间尺度下内江生态环境需水的主要限制因子，并基于内江水量、水质、泥沙及水体透明度的不平衡问题，提出了“约束水量”概念，定量计算了需水量的上限阈值；针对长江水沙分布的不均性及内江水位的多变性，逐月计算了内江生态环境需水量。结果表明：内江生态环境需水年内分布不均，表现出动态变化特征，枯季高于洪季；枯季内江生态环境需水主要限制因子是景观娱乐用水，平均需水量为6．98×10^6m^3／d；洪季平均生态环境需水约2．29×10^6m^3／d，水质改善是主要决定因素；受长江水沙分布影响，洪季约束水量低于枯季，两季平均约束水量分别为6．22×10^6、9．82×10^6m^3／d，枯季较洪季增加了57．9％。

Influenced by the outer water body and tide-induced impact, the eco-environmental water demand of waterfront body which is located by tidal rivers always changes with a high frequency and complexity. Neijiang in Zhenjiang City was taken as a research area in this paper. The key restricting factors of eco-environmental water demand in different seasons were analyzed. Based on the imbalance problem among water quantity, water quality, sediment and water transparency, the conception of Restrictied Water Quantity that was used to illuminate the upper limit of eco-environmental water demand was put forward and calculated. In view of the asymmetrical distribution of water and suspended sediment of the Yangtze River and the changeful water lever of Neijiang, the eco-environmental water demand was calculated month by month. It was found that the eco-environmental water demand in Neijiang presented a dynamic characteristic and the distribution of it was asymmetrical in a year. The eco-environmental water demand in dry season and flood season was 6.98×10^6and 2.29 ×10^6m^3/d in average respectively, and the key influencing factors in the two seasons were water demand for landscape and entertainment and that for water quality melioration. The restricted water quantity in flood season and dry season were 6.22×10^6and 9.82 ×10^6m^3/d, respectively. Influenced by the asymmetrical distribution of suspended sediment concentration of the Yangtze River, the restricted water quantity in dry season was increased by 57.9% than that in flood season.