Hydrological Balance in a Eucalyptus Plantation Watershed in Minas Gerais (Brazil)

Abstract

The interpretation of the potential impacts of anthropogenic activities on water quality is essential in order to manage the suitability of land uses, particularly in the case of Eucalyptus plantations. The aim of this study was to evaluate the precipitation, interception, and evapotranspiration of Eucalyptus plantations at the catchment scale (719 ha; clayey soil) for a period of over 2 years (2008–2011) in the Riacho Fundo Watershed (Felixlândia, Minas Gerais, Brazil). The possible relationships between streamflow, evapotranspiration, and net precipitation were also evaluated as a basis for taking management decisions and choosing future modeling options. Rainfall and evapotranspiration were measured with two rain gauges and two evapotranspirometers, respectively. A triangular weir and a levelogger/barologger were used for the streamflow measurements. Net precipitation was calculated through six plots in which throughfall and stemfall were measured. The rainfall showed values close to the expected average for the region (approximately 1,100 mm). Rainfall interception by the Eucalyptus crop in the period was approximately 12% of the gross precipitation, whereas the monthly runoff coefficient was of 38%. Average streamflow during the study period was 37.8 l s−1, having reached 18.3 l s−1 in the dry season and 51.4 l s−1 in the rainy season. These features illustrate the intra-annual variation of streamflow. No significant linear correlations were found between runoff and precipitation, which indicates the need of more complex models to include the occurrence of lagging effects of precipitation on the streamflow and the impact of the management.