Point to Area Rainfall Relationships Using Radar Data (PAP014809)

Código

PAP014809

Autores

José Rodolfo Scarati Martins, Ligia de Souza Girnius, Marcos Guilherme Moreira Pinto

Tema

Urban Floods

Resumo

Point to area rainfall relationships are useful in drainage systems planning and design, especiallywhen lumped simulation tools are applied or distributed rainfall patterns are not available in the studyareas. In order to proper evaluate and consider the effective spatial distribution, several different pointto area relations have been used over the world, including famous US Weather Bureau`s and Miller`srelations, based on the conventional rainfall records and considering frequency, surface area andstorm duration dependence. In the last 10 years new relations were constructed using radar data,after the benefits of this spatial high resolution monitoring technique. This article presents thedevelopment of a point to area relation considering the last 10 years of radar monitoring in the upperpart of Tiete River basin where the city of Sao Paulo (Brazil) is located, addressing different goalssuch as drainage system assessment and scenarios modelling.Sao Paulo meteorological radar tracks a 250km radio area producing rainfall maps at 3.000mconstant altitude (CAPPI) each ten minutes. These data area consisted and correlated with a groundstations network and stored in ascgrid files with 2 x 2 km spatial resolution. Using an algorithm toselect rectangular surface averaged rainfall from 50 to 2500 km² and durations from 1 to 24 hourscurves where produced and adjusted to reflect point to area reduction factor as functions of thesurface area and duration. Resulting values where combined to regional IDF relationship establishedafter long time series station in the basin, in order to associated return periods. Resultant curveswhere compared to traditional ones and other relations established with radar data.