Subdaily rainfall amounts estimation for complete hydrological year and dry season

Código

I-EBHE0142

Autores

MILENA GUERRA DE AGUILAR, EDUARDO DE OLIVEIRA BUENO

Tema

WG 1.10: Hydrologic Design - Solutions & Communication

Resumo

Subdaily rainfall amounts are required for many hydrologic designs, such as rainfall-runoff simulations or for modeling flashfloods. Nonetheless, time series with high temporal resolution, without gaps in the data, are often unavailable. To manage the lack of high-resolution subdaily data, one alternative is to disaggregate daily precipitation to subdaily amounts through disaggregation methods. Pfafstetter (1957 and 1982) stablished disaggregation coefficients for high temporal resolution durations for 98 rainfall stations in different regions of Brazil. It is recommended that those coefficients should be used in case of the total absence of data in the study area. Therefore, this study presents the estimation of new disaggregation coefficients for Belém city, located at Pará state, northern Brazil, using the Belém rainfall gauge (A201). This automatic rainfall station is monitored by the National Meteorologic Institute (INMET) and has an hourly resolution. Also, the disaggregation coefficients were developed for the complete hydrological year and dry season, to estimate all-year extreme events and to estimate amounts for temporary structures and for flow diversion with maintenance works, which are often made in the dry season. The results showed that, with local hourly data, disaggregation coefficients were significantly different from Pfafstetter (1957 and 1982) and there is a distinctive behavior between complete hydrological year and dry season coefficients. Overall, this study indicates the need to obtain new disaggregation coefficients with local high temporal resolution data and to illustrate the impact of the updated coefficients in hydrologic studies and hydraulic designs.