Determination of the Runoff Coefficient (C) in catchments based on
analysis of precipitation and flow events
Abstract
Runoff coefficient (C) values are tabulated and enshrined in
hydrological engineering. Its values are considered to be constant
although it may not correspond to reality. In the same catchment, they
can vary according to the intensity, temporal and spatial distribution
of precipitation events, humidity conditions, soils and land uses. This
study had the objective of analyzing extreme events of precipitation and
their corresponding flows to obtain experimental runoff coefficients (C)
and compare them with the tabulated values. The study was conducted in
five experimental catchments in the state of São Paulo, Brazil, with
different land uses. The runoff coefficients (C) were obtained from the
analysis of hydrograms and using a digital filter, which allowed the
separation of the direct runoff, of the total flow. We observed a
variation of the flow coefficient values between catchments different
from those obtained from the tables. The runoff coefficients had a high
correlation with land use. In the catchments with original vegetation
cover, such as cerrado and forest, it varied little among the events
analyzed, differently from the catchments where land use is diversified,
with predominantly agricultural and urban occupation.