Methodology for IDF equation based on reduced pluviograph records

Author(s)

Penner, Giovanni Chaves ; Wendland, Edson ; Goncalves, Moises Marcal ; Adam, Katiucia Nascimento

• Document type: Journal article
• Source: REVISTA BRASILEIRA DE CIENCIAS AMBIENTAIS; v. 58, n. 3, p. 10-pg., 2023-09-01.

Abstract

In the climate change scenario, extreme rainfall events are increasing in significance and frequency. It is essential to estimate the maximum precipitation intensity for designing hydraulic-hydrological structures, such as macrodrainage. Thus, this study makes a comparison between disaggregation coefficients and forms of the intense rainfall equation to determine an Intensity, Duration and Frequency (IDF) equation for Barcarena-PA. The rainfall historical series available in the Hidroweb database extends between 1981 and 2018. The Gumbel distribution presents the best fit in the return periods: 2, 5, 10, 50, 100, 200 and 1000 years, by the following tests: Filliben, Variance and Kolmogorov-Smirnov. The disaggregation of 1-day precipitation into shorter durations was done in two ways: using disaggregation coefficients recommended by the literature, as well as local disaggregation coefficients. For the construction of the IDF equation, two frequently used representations were considered: the first based on the determination of the coefficients: K, a, b and c; and the second, described in the Pluviometric Atlas of Brazil (APB), determines the coefficients: A, B, C, D and delta. The results indicated that the use of local disaggregation coefficients, in this case DCBarcarena, with adjustment coefficient R-2=0.9945, together with the use of the equation described in the APB, provides the best fit, R-2=0.9998, to historical data. When compared with other IDF equations from Barcarena-PA, the previous finding is clear in terms of underestimating the intensity values. Thus, the methodology presented here can be extended to locations with reduced sub-daily rainfall records associated with large annual maximum daily rainfall records. (AU)

• FAPESP's process: 22/10206-4 - Management of aquifer recharge in different regions of Brazil and availability for agricultural use
• Grantee: Edson Cezar Wendland
• Support Opportunities: Regular Research Grants