Rainfall interception in different forest formations in the southern region of Brazil

ABSTRACT

Rainfall interception by vegetation (I) can affect the hydrological behavior of a watershed, influencing the hydrological modeling processes. The limitations of monitoring and the wide variety of Brazilian climate and vegetation make it difficult to estimate the interception process. Therefore interception is often overlooked or underestimated in hydrological modeling. This study analyzed the rainfall interception in two forests with native vegetation belonging to the Atlantic Forest biome (MA1 and MA2 plots), and a eucalyptus forest (RE plot); located in southern Brazil. The throughfall (Pi) and stemflow (Et) were monitored for low cost collectors. Forty Pi collectors were used in MA1 plot and 20 collectors in MA2 and RE plots, and three Et collectors in each plot. In total 40, 34 and 22 collections of Pi and 17, 18 and 6 Et collections in MA1, MA2 and RE plots, respectively were analyzed. The total precipitation (P) observed was equal to 2046.50; 1726.23 and 957.96 mm; and total Pi found was 75.97; 82.40 and 78.07% of P, for the plots MA1, MA2 and RE, respectively. The Et was equal to 5.69; 2.91 and 11.09% P; and the estimated I was 17.76; 16.90 and 14.56% P, for MA1, MA2 and RE plots, respectively. Observed values of Pi and I are within the range reported by other authors for similar vegetation, however monitored Et was well above the reported results. The adjustment ratios presented limitations due to the number of Et collectors used and the number of Pi and Et collections monitored, especially in the RE plot; and also because of the large spatial and temporal variability of the processes analyzed, that make the monitoring process difficult.

Keywords:
Atlantic forest; Throughfall; Stemflow