Developing a national-scale hydrological model for drought monitoring in Ireland

Ireland’s climate is changing with the same pattern as global trends. This has the potential to have significant impacts on precipitation and water availability throughout the country. It is vital to be able to quantify the size of these impacts. One way to do this is by hydrological models tuned for the extremes of interest. This study focuses on the development of a national scale hydrological model calibrated for droughts and low flows across Ireland. A total of 332 catchments have been used to calibrate and validate the national scale model hydrological model using the Modular Assessment of Rainfall-Runoff Models toolbox (MARRMoT) over the chosen 332 catchments. These catchments range in sizes (50km² to 10,800 km²) and all chosen catchments have a minimum of 30 years of data available so that the model calibration and validation can be performed adequately. A few different objective functions focusing on droughts were used in calibration and validation including Kling and Gupta efficiency of discharge KGE(Q) function and logarithmic transformation based KGE. Initial results show that the simulated discharges can reproduce the observed discharges across the majority of catchments and that catchment size and the amount of baseflow are the important factors that influence the accuracy of the simulations.