基于健康评价的生态河道断面优化设计

Optimum Cross-Section Design of Ecological River Based on Health Assessment

摘要: 针对白洋淀流域XA新建城区的水系建设，通过构建适用于规划阶段的河流健康评价指标体系，从水文、水质、水系结构三方面、共7项指标，综合评价不同断面设计方案对河流健康的影响。结果表明，影响研究区域河流健康的主要断面参数为底宽和糙率系数，通过优化断面方案可以提高水系健康指数，但整体水平仍受制于补水量大小。现有补水量条件下，河道不利点的底宽不宜超过1 m、糙率系数宜为0.05，以维持生态流量、生态水深、连通性等指标；水面率满足程度、流动性水平和总氮的达标程度是限制研究区域河流健康水平的主要指标，无法通过断面优化设计的方法使其充分达标，故建议进一步考察规划要求的合理性并采取其它措施来提高指标的达标程度。

Abstract: In view of the river system in the newly-built XA urban area of Baiyangdian river basin, a river health assessment index system suitable for the planning stage is constructed to comprehensively evaluate the influence of different cross-section schemes on river health from three aspects of hy-drology, water quality and river system structure, including 7 indexes in total. The results show that the main parameters affecting river health in the study area are bottom width and roughness coefficient. The health index can be improved by optimizing the cross-section schemes, but it is still limited by the amount of water supplement. Under the existing planning, the bottom width of unfavorable points of river should be less than 1 m, and the roughness coefficient should be about 0.05, in order to maintain the flow, depth and connectivity. Water surface rate satisfaction level, fluidity level and total nitrogen standard level are the main indexes restricting river health level in the case area, which cannot reach the standard of the planning by the method of cross-section optimization design. Therefore, it is suggested to further investigate the rationality of the existing planning and take other measures to improve the level of the indexes.