With the objective to analyze the hydrological processes and the water balance, a simplified water balance method and the modified Penman formula were applied to the Ribeirão da Onça river catchment in Colombo city, Paraná State. For the analysis, the data obtained during the monitoring period from 1997 to 2000 were utilized. The results showed that the values of the real evapotranspiration estimated by the method of the simplified water balance were negative for the certain periods and for other period sometimes more than those of the potential evapotranspiration estimated by the modified Penman formula. It implied the existence of significant groundwater recharge from other catchments to the study area, and indicates that the simplified water balance method was not suitable for the hydrological study of this karst catchment. The value of the groundwater recharge received by this catchment was estimated as 554 mm/year for the analysis period.
Water balance; evapotranspiration; karst
