Exploration Of Radar Precipitation Estimation In Flash Flood Early Warning

Research on flash flood is one of the focus areas of the world currently. This paper, which is on the subject of flash flood warning, recalls the research progress of flash floods warning and radar precipitation, and introduces a new method of flash flood warning:"3-Map" flash flood warning. It includes a static short-duration rainstorm high risk zoning map, a dynamic threshold runoff values map and a dynamic critical rainfall distribution map, which is obtained by the united information of radar and ground rainfall information. The linkage of these three maps can achieve the objectives of flash floods warning. The features of wide range of detection, real-time and high spatial and temporal resolution make radar plays a crucial role in early warning and forecasting. This paper introduces a new method of flash flood early warning and forecasting and analyses the effect of radar precipitation estimation in it. The following are preliminary conclusions.(1) It still needs development and innovation for the reason that there still do not have a reliable and accurate flash flood warning system in the world.(2)"3-Map" flash flood warning method, which is put forward by Bingzhang Lin, is different from the previous method. Its innovation is the introduction of short duration rainstorm high risk zoning map, which is based on the theory of regional linear moment. This map, which reflects high risk area of the actual rainstorm in history, contributes to flash flood warning and the prevention of flash flood.(3) Comparison of four calibration methods gives the conclusion that Kalman filter integrated variational method is optimal.(4) The accuracy of Kalman filter calibration increases with the number of observations. Therefore, increasing the sample size of the Kalman filter calibration is important to the improvement of Kalman filter calibration.(5) QPEGS is able to achieve rainfall estimates of7radars in real time simultaneously; SWAN can offer1-hour precipitation estimation, alarm of heavy rainfall in large areas. These two systems can serve flash flood warning. There will be a possibility of flash flood as the estimation of rainfall offered by them is larger than its critical rainfall in a region.