Establishment and Application of the Assessment System on Ecosystem Health for Restored Urban Rivers in North China.

The study on ecosystem health evaluation for restored urban rivers is of specific significance to improving river health and realizing the adaptive management for urban river ecosystems. Based on the health definition of restored urban rivers in North China, this study attempted to set up a system of alternative indicators on ecosystem health assessment, including water quality, water regime, aquatic organism, riparian environment, and physical morphology. Additionally, a set of health assessment system was proposed, including selection of assessment indexes and determination of assessment criteria and health classes. Taking seventeen typical restored urban rivers in Beijing as the assessment target, the said system was applied in assessing urban river health in 2016 and 2019. As the assessment results indicated, in 2016, the health statuses of 29 percent of urban rivers were ordinary, while 71 percent of urban rivers were somewhat inferior. In 2019, the health state of only one urban river reached "good" level. The health statuses of 88 percent of urban rivers were ordinary, and 6 percent were somewhat inferior in terms of comprehensive health index. In 2019, the health states of rivers improved significantly compared with that of 2016, which indicated that most urban rivers saw marked improvement in ecosystem health after ecological restoration. The health assessment system proposed in the paper not only could be applied to regular evaluation of restored urban rivers in the north but also was suitable for a contrastive health-state analysis between different years prior to or after the restoration. In order to carry out adaptive management of water ecology in urban rivers, the measures of ecological restoration could be adjusted based on the regular health assessment and health weakness analysis.