Evaluation of 21st Century CMIP5 GCM Outputs for Climate Change Impact Assessments in Shire River Basin in Malawi
Abstract Data scarcity globally has impeded our understanding of hydrological processes. This study was aimed at evaluating skills of models in reproducing past climate in the Shire River Basin (SRB) in Malawi for future climate impact assessments. The study used data, simulated by Global Climate Models (GCMs), participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). A total of 52 models were considered comprising a mixture of models in the Representative Concentration Pathways of RCP4.5 and RCP6.0. The mean annual bias, correlation, extreme precipitation indices obtained from the RClimdex package of R software program and frequency distributions were used to quantify the accuracy of the GCM simulations. On the precipitation indices, emphasis was placed on the frequency indices (number of heavy precipitation days (RR ≥ 10 mm), R10mm, number of very heavy precipitation days (RR ≥ 20 mm), R20mm, number of extremely heavy precipitation days (RR ≥ 25 mm), R25mm, Consecutive Dry Days (RR < 1 mm), CDD and Consecutive Wet Days (RR ≥ 1 mm), CWD and on the intensity indices (daily maximum precipitation, RX1day, 5-day maximum precipitation, RX5days, annual total wet-day precipitation, PRCPTOT and very wet days, (R95P). Study results have revealed that there is variation in the performances of individual models and that the overall performance of the models over the SRB is generally low. Some individual models perform better than the multi-model ensemble. Results have also shown the better performance of the following models: ACCESS1-3_rcp45_r1i1p1, BNU-ESM_rcp45_r1i1p1, CSIRO-Mk3-6-0_rcp45_r3i1p1, CSIRO-Mk3-6-0_rcp45_r8i1p1 and GFDL-ESM2G_rcp45_r1i1p1 of medium-low emission pathway, RCP4.5, in replicating the historical extreme precipitation for Shire River Basin.