Zoning method of aquatic ecosystem functional management fourth-level region in the Daqing River Basin, China.

Watershed management needs more information on ecological function and services in large regions. Spatial units are particularly important for the watershed management. Zoning of aquatic ecosystem functional management region refers to the zoning of terrestrial ecosystems as per the characteristics of aquatic ecosystems, providing an ecological background and basic spatial units for water environment management in basins. Although basin water environment management based on aquatic ecosystem functional management region and control unit is highly effective in practice, the current need for refined management of water environments cannot be met by existing zoning schemes of aquatic ecosystem functional management regions and control units. In response to the need to protect basin water environments, which is raised in the 14th Five-Year plan, a zoning method of aquatic ecosystem functional management fourth-level region for basins is proposed in this study. It features an effective integration of aquatic ecosystem functional management regions and control units and township-level administrative divisions, thus contributing to the implementation of a basin water environment management system that fulfils the zoning, grading, classification and period goals of aquatic ecosystem functional management. In this way, it can satisfy the business application of administrative management and refined management of water environments, which features coupling terrestrial and aquatic ecosystems and unification of water resources, water environments and aquatic ecology. The feasibility and effectiveness of the proposed zoning method were verified by using the Daqing River Basin, Beijing-Tianjin-Hebei region, China, as a case study. The results were accepted by the Ministry of Ecology and Environment and the Haihe River Water Conservancy Commission of the Ministry of Water Resources, which can provide scientific rationale and technical support for the accurate and differentiated watershed water environments management and ecological restoration of coastal wetlands in the Haihe River Basin based on aquatic ecosystem functional management fourth-level region with clear responsibility for the local government during the period of the 14th Five-Year plan.

eDNA metabarcoding revealed differential structures of aquatic communities in a dynamic freshwater ecosystem shaped by habitat heterogeneity.

Freshwater ecosystems have been threatened by complicated disturbances from both natural and anthropogenic variables, especially in dynamic and complex river basins. The environmental DNA (eDNA)-based approach provides a broader spectrum and higher throughput way of biomonitoring for biodiversity assessment compared with traditional morphological survey. Most eDNA metabarcoding studies have been limited to a few specific taxa/groups and habitat scopes. Here we applied the eDNA metabarcoding to characterize the structures and spatial variations of zooplankton and fish communities among different habitat types in a highly dynamic and complex freshwater ecosystem of the Daqing River basin (DRB). The results showed that varied species spectra of zooplankton and fish communities were identified and unique dominant species occurred across habitats. Additionally, markedly spatial distributions of biotic community structures were observed in areas with different habitat characteristics. Natural variables, including geographic distances and gradient ratio, as well as anthropogenic factors of chemical oxygen demand (COD) and organic chemicals demonstrated significant effects but different outcomes on the structures of zooplankton and fish communities. Moreover, the relative abundances of specific aquatic taxa were associated with the gradient of particular environmental variables. This case study verified the distribution patterns and differentiation mechanisms of biotic communities under habitat heterogeneity could be captured by application of eDNA biomonitoring. And habitat-specific and even species-specific environmental stressors would be diagnosed for improving management of complex river basins.

Analysis on historical flood and countermeasures in prevention and control of flood in Daqing River Basin.

The Daqing River Basin has long been seriously threatened by floods. The construction of Xiong'an New Area has put forward higher requirements for the flood control system of the basin. Researches on the characteristics of the flood control system in the Daqing River Basin, the causes of the flood and the historical flood were conducted with the purpose to have a clear understanding of the deficiency of the existing flood control system in the Drainage Basin and figure out the countermeasures to improve the flood control capacity of the Drainage Basin by taking the development process of the flood control system in the Drainage Basin into consideration. Analysis was conducted on the causes, flood process, the process of regulation and storage of reservoirs and depressions as well as flood disaster with the flood occurred in August 1963 as the major research object. Besides, the deficiency of flood control system of the Drainage Basin in terms of flood control system and the flood occurred in August 1963 (also called 63.8 Flood). According to the research, the major problems in the current flood control system of the Daqing River Basin are mainly concentrated on Baiyang Lake with blocked internal water transmission and insufficient drainage capacity, which makes it difficult to cope with the flood exceeding the designed level. The great change of water level will also destroy the ecological balance of Baiyang Lake itself. In addition, during the construction of the New District, some flood storage and detention areas in Baiyang Lake will be deprived of the capability in regulation and storage, which will increase the difficulty of flood control in the downstream areas. Combined with the existing flood control system and aiming at the construction of Xiong'an New Area, the concepts of flood control system such as developing the Xiaoguan flood diversion way, rebuilding the new housing hub and strengthening the dredging of downstream river are put forward.