Hydrology and hydrological extremes under climate change scenarios in the Bosque watershed, North-Central, Texas, USA

Abstract

Abstract This study evaluates hydrology and hydrological extremes under future climate change scenarios. The climate change scenarios were developed from multiple Global Circulation Models (GCMs), Representative Concentration Pathway (RCPs) scenarios, and statistical downscaling techniques. The hydrological model, Soil Water Assessment Tool (SWAT), was calibrated and validated using the Differential Split-Sample (DSS), where the observed period was divided into relatively 'dry' and 'wet' periods based on observed streamflow. This was to ensure hydrological model robustness simulating contrasting climate conditions. The model was also calibrated and validated at the multi-gauges of the watershed. The multi-model ensemble and single-climate model simulations were used to quantify changes in hydrology and hydrological extremes under future climate scenarios. Future climate change scenarios revealed a reduction in precipitation (in the order of -9.1% to 4.9%) and a consistent increase in maximum temperature (0.34℃ to 4.10℃) and minimum temperature (-0.15 ℃ to 3.7℃) in different climate model simulations. The climate change scenarios triggered a reduction of surface runoff and streamflow and a moderateincrease in evapotranspiration. A decrease in high flow (Q5) and low flow (Q95) was projected from future climate change scenarios. A higher reduction of low flow and annual minimum flow is also simulated in future climate scenarios. Whereas an increase in annual maximum flow is simulated in climate change scenarios developed from the RCP8.5 emission scenario. The study suggests optimal water management structures which can reduce the effect of change in high and low flows.