城市河流生态流量核算对于水资源规划和河流保护非常重要。以往城市河流生态流量核算方法侧重于满足物种生境维持和污染物稀释的需求。然而，城市河流中很少存在需保护的物种，同时大量城市河流为混凝土化渠道，无需考虑物种生境维持需求；另外，随着城市水污染防治工程的建设，一些城市河流的污染问题可得到有效的控制。对于这类城市渠化河流，如果沿用以往的生态流量核算方法，即从物种生境和污染物稀释的角度来确定生态流量，生态流量的核算结果将很小，潜在地降低了未来水资源分配和管理中对河流生态保护的重视程度。为了更有效地核算渠化城市河流的生态流量，除了满足污染物稀释的需求外，本研究依据河流纵向水文连通程度的不同（高、中、低），提出了3 种情景下的生态流量核算方法。在高水文连通情景下，生态流量旨在维持一定的水流流速，以确保河流的自净能力并减缓藻类的繁殖；在中水文连通情景下，生态流量旨在维持城市河流中被拦水堰分割河段之间的纵向水力连通性，以确保河流中的物质、能量和信息间的交换；在低水文连通情景下，设计的生态流量将进一步减小，改为间歇地向城市河流补水，旨在满足被拦水堰分割河段间的间歇性连通。本研究以十五里河为研究案对象，研究结果表明新建立的生态流量核算方法可以提供更加精确、符合实际的生态流量核算结果，并为生态补水工程的建设和管理提供有效的指导。

Assessing environmental flows (e-flows) for urban rivers is important for water resources planning and river protection. Many e-flow assessment methods have been established based on species' habitat provision requirements and pollutant dilution requirements. To avoid flood risk, however, many urban rivers have been transformed into straight, trapezoidal-profiled concrete channels, leading to the disappearance of valuable species. With the construction of water pollution-control projects, pollutant inputs into rivers have been effectively controlled in some urban rivers. For these rivers, the e-flows determined by traditional methods will be very small, and will consequently lead to a low priority being given to river protection in future water resources allocation and management. To more effectively assess the e-flows of channelized urban rivers, we propose three e-flow degrees, according to longitudinal hydrological connectivity (high, medium, and low), in addition to the pollutant dilution water requirement determined by the mass-balance equation. In the high connectivity scenario, the intent is for the e-flows to maintain flow velocity, which can ensure the self-purification of rivers and reduce algal blooms; in the medium connectivity scenario, the intent is for the e-flows to permanently maintain the longitudinal hydrological connectivity of rivers that are isolated into several ponds by means of weirs, in order to ensure the exchange of material, energy, and information in rivers; and in the low connectivity scenario, the intent is for the e-flows to intermittently connect isolated ponds every few days (which is designed to further reduce e-flows). The proposed methods have been used in Shiwuli River, China, to demonstrate their effectiveness. The new methods can offer more precise and realistic e-flow results and can effectively direct the construction and management of e-flow supply projects.