| Altay City is one of the key flood control cities in Xinjiang,and it is also threatened by river flood and mountain flood disaster at the same time.There are more than 10 mountain flood ditches around the urban area,and the area of water collection is about 84km2.Since 1954,Altay has been attacked by 60 flash floods,especially for the prevention and control of flash floods around the urban area.The determination of prevention measures is of practical significance to the prevention and control of local mountain flood disaster,which can provide guidance and foundation for the prevention and control of the disaster.Taking small watershed of Kelan river in Altay City of Xinjiang as the research field,this paper analyzes the causes of mountain floods disaster,and investigates and analyzes the present situation of the construction of mountain flood disaster prevention and control system,the effectiveness of flood control and the existing problems in the operation of Altay City.Then,taking the general mountain ditch around Altay city as the typical calculation area,the one-dimensional hydrodynamic model is used to simulate the water surface line of the typical area,and the critical flow is determined by the simulation results of the water surface line,and the early warning indexes of each flood ditch around Altay city in different periods are calculated.The analysis of the characteristics and causes of mountain flood disaster shows that the slope drop is steep around the urban area,and the slope drop is slow after Mountain flood ditch enters the Klan River valley,which provides favorable topographic conditions for the rapid collection and dumping of the local sudden mountain flood disaster.The local heavy rainfall around the urban area is prone to local heavy rainfall,and the land in the water collection area is mostly desert grassland,and the low vegetation coverage rate provides favorable conditions for frequent rainstorm and flood.Through the investigation and analysis of mountain flood disaster prevention and control system,it can be seen that through the implementation of mountain flood disaster prevention and control engineering measures,the flood control standard of each mountain flood ditch has been greatly improved.From the construction and operation of mountain flood disaster early warning system at county level,it can be seen that most mountain flood disaster prevention and control projects are implemented in mountain flood disaster early warning and early warning system,the operation and maintenance investment of early warning system is insufficient,and the availability of equipment collection data is poor,which restricts the application of local mountain flood disaster early warning system.Based on the backstepping method of water level and discharge relationship and the reasoning formula method,the early warning indexes of 1/6h、1h、6h and 24h early warning period in Mountain flood ditch gully around Altay City are calculated,and three kinds of early warning situations.According to the current situation of the built flood control facilities,the critical flow is taken as the main early warning index.The critical flow indexes of horticultural field ditch,Jiang Jun Shan gully,Ka la Su gully and repair plant ditch around the urban area are 41m3/s,98m3/s,197m3/s,and 46.8m3/s respectively.Early warning and forecast scheme based on the measures of flood control projects which can provide a certain reference for improving the ability of regional mountain flood disaster prevention and control.In the next step,the construction of soil and water conservation project and ecological environment control project can be increased in the aspect of engineering measures.In the aspect of non-engineering measures,the construction of simple water level station should be improved,the data acquisition ability of mountain flood disaster early warning platform should be improved,the benefit of urban flood control system should be brought into play,and the defense ability of mountain flood disaster in this area should be effectively improved. |
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