Study on multi-resolution decomposition of rainfall in wenrui plain based on Mallat wavelet analysis algorithm

Wenrui plain is located in the southeast coast and belongs to Lucheng District, Ouhai District, Longwan District and Rui'an City of Wenzhou. This area is the core area of Wenzhou's economic and regional development. Due to the dual influence of inland climate and marine climate, the rainfall law of Wenrui plain is generally difficult to be found. The existing flood disaster management system and flood control and drought relief command system are based on the analysis of rainfall. In view of the complexity of rainfall, it is difficult to find its internal law and trend by using traditional analysis methods. Based on the above problems, this paper introduces Mallat wavelet fast decomposition algorithm to decompose the rainfall in Wenrui plain. By decomposing the original rainfall sequence into multiple different resolution sequences, we can observe the steady change trend and noise information of rainfall sequence, so as to lay a good foundation for subsequent rainfall prediction. After comparing and analyzing the effects of using db3 function and db4 function and decomposing layers 3, 4 and 5, it is found that when using db4 wavelet analysis function to decompose to layer 3, the stationary series and noise series are obvious, and the trend of rainfall can be clearly found from the stationary series, laying a good foundation for subsequent rainfall prediction.