Disaggregation of Daily Rainfall in the State of Mato Grosso

Abstract

Intense rainfall is an environmental variable of great importance in the planning of hydraulic works, being usually cha-racterized by intensity-duration-frequency (IDF) curves obtained from rainfall data. In places that do not have rainfall stations, the IDF curves can be obtained using daily rainfall disaggregation methods. Thus, this work sought to adjust the 1-day rainfall disaggregation coefficients and the parameters of the Bell equation in the State of Mato Grosso, as well as to verify which method provides better results in estimating rainfall of different durations and return times. The adjustment of the two methods was performed by analyzing the relationship between rainfall obtained from the IDF curves of 14 rainfall stations in the state and the annual series of maximum daily rainfall, in the same locations, adjusted to the generalized distribution of extreme values. Due to the low frequency of rainfall lasting more than 360 minutes, the first rainfall disaggregation coefficient obtained was 1 day in 6 hours (0.53). The adjustment of both methods was responsible for reducing the associated errors when compared to the national coefficients, thus, they are indicated for obtaining rainfall of less than 1 day from rainfall data in Mato Grosso.