Processos hidrológicos de uma microbacia com Mata Atlântica, na região da Serra do Mar, SP

Abstract

A field experiment was carried out to better understand the hydrological process of stormflow generation in one of the three small experimental catchments of the Forest Hydrology Laboratory, Cunha, State of São Paulo. A hillslope portion of the catchment D was selected so that all stormflow components could be measured. Monitoring was carried out during the 4 rainy months of December 1999 to March 2000, which allowed the characterization of the hydrological behavior of catchment D. The results showed that 62% of the rainfall events during the experimental period were smaller than 10 mm, and that 88% of them had intensity smaller than 10 mm/h. However, some very high precipitations were also registered. The infiltration capacity of the soil (18 mm/h) was sufficiently high to account for the infiltration of over 94% of the precipitations, thus decreasing surface runoff. The overland flow component of the stormflow during the experimental period was significantly low (0,2 % of the precipitation). The values of the flow density in the soil were small, with alternating periods of upward flow with others of downward flow. The average values of soil humidity were always very close to the field capacity, which helps to explain the reason of the shallow ground-water, which arises so instantly after rainfall in many parts of the catchment. These saturated conditions, on the other hand, favor the generation of saturation flow, as well as explains the relatively small variation of the vertical soil water fluxes. Therefore, the knowledge of these dynamic conditions of the variable source area is very important for catchment anagement prescriptions in the region