| Watercourse is the main flood channel and the flood control capacity of river dike directly affects the riverbank and its surrounding people's life and production. Therefore, river regulation, especially the construction of embankment is one of the important engineering measures of disaster prevention and reduction. Yutian section of Jiyun river did not meet the design standards due to historical reasons, which led to some problems in this section, such as insufficient of flood channel cross, embankments weak and vulnerable spot. These problems seriously influence the safety discharging of Jiyun river, so the implementation of Jiyun river regulation project is necessary. Through the research on the present situation of the embankment of Yutian section, this article put forward specific management schemes and measures. The main research contents and results are as follows:(1) Through the study on the various reasons as expanding width of the main channel, flow condition, engineering construction land and execution condition under different retreat dike level, this paper selects the retreat dike scheme of 200 m. At the same time, this research uses uneven constant flow method to calculate the water surface line and determine the design water level as well as determine the levee crown elevation with considering free board. Through using seepage stability analysis and slope stability against sliding analysis to determine the levee cross-section, the ultimate embankment line and embankment structure are formed. Through the research, Jiyun river, is up to design flood with recurrence interval of 20 years, design mechanical waterlogging drainage with recurrence interval of 5 years and design spontaneous drainage with recurrence interval of 10 years, can effectively protect people life and property safety along the bank.(2) Through the analysis on engineering construction organization feasibility, building material markets along the project region are considered plenty of goods. The main construction contents are embankment reinforcement and refund dike engineering. The construction region do not need diversion project, of which the external transportation conditions is convenience and the field traffic need to build causeways, so the construction work is feasible. Meanwhile, the research mainly studied the conversion land of cropland to river after retreat dike, the temporary road construction in the construction process, the borrow area inside the embankment and the reclamation of construction camps, including remediation principles, scope of reclamation, land reclamation measures, etc.(3) Through the analysis on the environmental capacity, as a result, the local production is less affected by the engineering construction land and most of the villages account for less than 10% of the total land. Therefore, the production settlement for the engineering construction land is proposed by medium and low yield farmland rehabilitation as well as land dispensing. Considering the number of involved households is less and the buildings mainly are dispersed, the relocation sites can be selected around the residential areas of the village or from unoccupied homestead within the residential areas.(4) It shows that the project is economically feasible through the study on the national economic evaluation. Sensitivity analysis of the project is performed with selection of investment in fixed assets and benefit as the sensitivity factors. Under the condition of 15% reduction in benefits or 15% increase of investment in fixed assets, the economic internal rate of return is greater than the social discount rate, the economic net present value is greater than zero, and the economic benefit cost ratio is greater than 1.0, which generally show that the project has a certain ability to resist risks. |
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