Assessment of ecological system in East River and corresponding ecological restoration strategies

Abstract

The stream ecology of the East River is investigated by using the benthic macro-invertebrates as indicator. Samples were taken from 12 selected sites with different environmental conditions from upper reaches to lower reaches. It is found that the biodiversity and bio-community index of benthic invertebrates maintain a relatively high level respectively in the upper reaches and middle reaches of the river, but they are reduced to nearly zero in the lower reaches. The analysis on samples obtained from the Zengjiang Bay and Xizhijiang Oxbow Lake indicates that the major ecological stress is loss of habitats due to reclamation and separation of riparian water from the river. The restoration strategies are suggested accordingly. The strategies include: 1. creating multiple habitats with high habitat diversity, such as riparian lakes, wetlands, backwater and sluggish flow zones and reconnect separated lakes with the river; 2. adjusting the operation scheme of the upstream reservoir to mitigate the impact induced by instantaneous fluctuation of flow discharge; 3. stabilizing river banks, controlling river erosion and protecting the riverside vegetation.