Torrential Rain Events Assessment Model for the Upstream of the Huaihe River Basin

Torrential rain disaster is one of the most serious meteorological disasters in China, the assessment of which has important practical and theoretical significance. On the basis of precipitation data, statistics analysis is carried out to establish the torrential rain events assessment model, and the torrential rain events which happen in the upstream of the Huaihe River Basin is assessed with this model. Four indicators are selected to describe torrential rain events in this assessment model, which are averaged area daily rainfall, maximum area daily rainfall in area daily, rainfall coverage range and rainfall duration. Through the statistical analysis of historical torrential rain events data, several grades are defined for the four indicators according to the probability distribution, and then the grade standards assessment matrix is established. The degree of the torrential rain events is calculated by the method of the Euclidean distance, through Euclidean distance between the torrential rain events indicator vector and each column vector of the assessment matrix, the degree of this torrential rain event can be determined. Through the assessment of historical and live torrential rain events which happen in the upstream of the Huaihe River Basin, the assessment results correspond well with the actual impact of the torrential rain disaster, which indicates that the degrees of torrential rain events assessed by this torrential rain events assessment model is reasonable. The pre-assessment can be made by this torrential rain events assessment model to publish warning information when the forecast data are used, and the assessment accuracy has a positive effect on the forecast accuracy.Through the assessment of historical torrential rain events by this model, the results show that in 226 historical torrential rain events, there are 47 times belonging to level 1, 86 times belonging to level 2, 55 times belonging to level 3, 25 times belonging to level 4, 9 times belonging to level 5, 3 times belonging to level 6, and just 1 time belonging to level 7, which are consistent with the theoretical analysis. According to the assessment results, the most serious torrential rain events happen in 2007, which is consistent with the historical facts.The correlation between the assessment levels of torrential rain events and the Wangjiaba water levels passes the test of 0.005 level, inferring that the selection of the assessment region and the assessment results of the torrential rain events of this research are rational.The analysis of the assessment results shows that the torrential rain events happen 2 days before the peak of Wangjiaba water level, which has important significance to guide the disaster prevention and mitigation. However, the assessments of the influences of torrential rain events are insufficient, which need further research.