Modeling hydrological variability of fresh water resources in the Rio Cobre watershed, Jamaica

• Sensitive flow parameter in were identified and the SWAT model was calibrated
• Spatiotemporal distribution of hydrological processes was determined
• 52% of rainfall is lost by evapotranspiration
• The groundwater contributes 42% to the water yield

Freshwater resources and healthy coast lines are the basis of ecotourism in the Caribbean islands. The vulnerability of these islands to natural and human-induced disasters and their inability to cope with the problem necessitate the understanding of the hydrological processes and responses of the watersheds to various stressors. The main objective of this study is to characterize, model and analyze the temporal variability of hydrological processes in the Rio Cobre watershed, Jamaica using the Soil and Water Assessment Tool (SWAT). Determination of the temporal hydrological water balance and the spatial distribution of hydrological processes in the Rio Cobre watershed are discussed. The ability of a watershed model to accurately predict the hydrological processes is evaluated through parameter sensitivity analysis, model calibration and validation. Sequential Uncertainty Fitting (SUFI-2) calibration and uncertainty analysis methods were used for the set-up of the SWAT model. The model evaluation statistics for streamflow prediction show that there is a good agreement between the measured and simulated flows that was verified by the coefficient of determination (R2) and Nash Sutcliffe efficiency greater than 0.5. Past studies suggested that the prediction efficiency of the calibrated model can be judged as satisfactory if R2 and NSE values are > 0.5. Model simulation results are subject to uncertainties due to input data, model structure and errors in parameter estimates. The choice of the retention parameter estimation method, routing method, evapotranspiration estimation methods might significantly affect the prediction of surface runoff and then the water balance. The hydrological water balance analysis indicated that above 52% of the annual precipitation is lost by evapotranspiration in the basin. Surface runoff contributes more than 12%, whereas the ground water contributes more than 42% to the total water yield. The calibrated model can be used for further analysis of the effect of climate and land use change as well as other different management scenarios on streamflow and other hydrological components. The model output can be used as a tool to develop appropriate adaption strategy to the effect of land use and climate changes.