Ireland's water budget— model validation and a greenhouse experiment

Abstract

In a previous paper (Mills, 2000) the author described a simple water budget model that was applied to Ireland for the period 1961-90. The budget stated the relationship between precipitation, evapotranspiration, runoff and change in water storage for a regular set of grid cells (each 25km² in area) that cover Ireland. The results of the model appeared to conform to the known climate of the period but no formal attempt at model validation was attempted. In this paper the author examines the relationship between the estimated 'surplus' water calculated for the catchment of the Shannon River with the measured discharge for that river. The close correspondence between these values suggests that the model is capable of estimating water budget components at this scale. A simple climate change experiment is presented that evaluates the impact of Greenhouse warming on the water budget of this catchment. The results indicate that although increased winter precipitation is predicted, increased rates of evapotranspiration results in drier summers.