The Flash Floods Assessment And Warning Analysis Of The Small Watershed

In recent years,severe rainfall and extreme flood has been occured frequently due to climate change.The frequently floods could bring huge damages and severe losses to small basins.Therefore,specific small basins management with torrential flood alarting and risk assessment is of great significant in providing evidence and guidence for disaster and flood prevention.In this paper,small basins management with torrential flood alrting and risk assessment is studied.A specific practical case of Tazigou small basin,located in the west of Liaoning province,is analyzed on behalf of small basins and systematic analysis of small basin flood's characteristics and cause of formation is discussed and carried out.In this paper,design rainstorm flood is calculated with consideration of all these characteristics and the stage and flow relation is reckoned by Manning's formula,a measurement method of alarting indicators and calculation principles of small basin flood is proposed ultimately.By modeling the torrential flood analysis through MIKE FLOOD model,risk assessment is thus realized.The analysis of this practical case indicates the following results:(1)The specific torrential flood alerting system for small basins can provide flood alarting value under various time interval(1h-24h)with different warning level(inform,warning,urgent)which is an useful information in decision–making for flood prevention.(2)Baded on the risk assessment method for small basins,a 2D distribution of flood inundated area(depth of inundated)of different recurrence periods for small basins.Disaster damage under different inundated areas could be quantitatively counted by integrating multiple impact indicators.And all kinds of properties losses caused by floods could be quantitatively estimated.After difining the dangerous zone and results of flood influences analysis,escape route and moving plan could be proposed.