Research On Functional Assessment And Restorative Planning On Revetments Along The Li River

Li River is a famous tourist attraction in Guangxi Province of China, as well as a major river for flood discharge. To ensure the navigation safety and protect the natural landscape, various revetments were established along the Li River from the end of 1980s, including engineering measures, plant measures and comprehensive measures. However, the status in quo and protective effect of these revetments are not clear, and there are few researches on functional assessment of revetments along the riparian. For these reasons, field investigation, functional assessment system construction and restorative planning proposals on revetments were carried out in this study, in order to lay foundation on functional assessment on revetments along the riparian and provide theoretical basis and guidance for the construction and management of restorative projects on revetments along the Li River.In this research, the status of existing revetments along the Li River from Guilin to Yangshuo were acknowledged after the detailed field investigation combined with image data, including the quantitative characteristic, length characteristic, type characteristic and distribution characteristic. Then engineering measures-masonry, engineering measures-gabion, plant measures and comprehensive measures, were selected to be four representative revetments, and contrasts on stability effect, revegetation effect and landscape effect of these four revetments were analyzed. Next, the functional assessment system was constructed using Analytic Hierarchy Process of qualitative and quantitative assessment. The final result on functional assessment of these four representative revetments was shown by the comprehensive evaluation index. The assessment result demonstrated that plant measures worked best, followed by comprehensive measures and engineering measures. And comparing two engineering measures, the gabion, which is more ecological, worked much better than the masonry. In addition, the revetments along the Li River from Guilin to Yangshuo were divided into different degrees according to the detailed information by field investigation and judgement from relevant experts’ experiment. On the basis of urgency degree and restoration scope, the revetments divided into three degrees:the first degree is badly in need of monolithic restoration, the second degree is in need of partial restoration and the third degree is no need of restoration. At last, restorative planning on revetments with different gradient, width, land-use types, vegetation condition and disturbance degree by human activities, belonging to the first degree and the second degree, was proposed preliminarily.