Evapotranspiration is important as a term in the hydrological cycle, eg in soil water and ground water balances and in salinisation. There are a number of equations which give an approximate value of evapotranspiration and the most commonly used equation is the Penman-Monteith equation. In this study the Penman-Monteith equation method will be compared with the water balance equation method. Field values for the water balance equation were collected at small forested peatland catchments in Connemara (Cloosh valley). Here the parameters in the water balance equation will be measured and evapotranspiration will be calculated directly. The ETp value obtained will then be compared with the values obtained from the Penman-Monteith equation. The difference in the ETp values is taken as the error. This error may provide a modifier term for application of the Penman-Monteith equation to such sites.
Last update: 15-December 1997