Application of Chicago Hyetograph Method to Heavy Rainfall Equations of an Alternative Model Obtained by Disaggregating Daily Rainfall

Abstract

Determining hydrographs for hydraulic works projects such as dams and reservoirs requires the definition of the design rainfall hyetograph. The Chicago method stands out as one of the most used methods, with the advantage of being easy to apply. However, the dependence on traditional and updated IDF equations can be pointed out as a limitation of the method. This study aimed to adapt and apply the Chicago hyetograph method with the intense rainfall equations of the alternative model, which stands out for its ease of obtaining and updating. The equations for estimating rainfall intensities for the duration before and after the peak of the hyetograph were presented. The equations were also adapted to obtain the accumulated depths or volumes of rainfall before and after the peak of the hyetograph. This information allows us to easily obtain the rainfall blocks for each interval of the hyetograph. The method was applied to determine the hyetograph based on the maximum daily rainfall, demonstrating each calculation step. The equations presented here can be implemented in electronic spreadsheets or programming routines, allowing Engineering professionals to apply methods that are more appropriate to local data.