Abstract:Considering the cumulative effect that heavy rainfall may cause, the concept of rainfall attenuation index was put forward and the relative intensity formula for the rainstorm process was established, so as to judge if it is a storm day. Starting from the disaster factors, the intensity of storm process and the influence region were taken as the evaluation index, and the comprehensive evaluation model of regional rainstorm process was established. Taking the middle and lower reaches of the Yangtze River as an example, based on the above evaluation model, the rainstorm process sequence was obtained, and then the rainstorm intensity grade in this region was evaluated by percentile method. The results were compared with the historical rainstorm process, which demonstrate that the assessment model is consistent with historical disaster records.