Evaluating the impact of climate change and human activities on streamflow variations based on the budyko framework in catchments of the northern Taiwan

Recently, the influences of climate change and human activities on global environment have been widely concerned. As the hydrological environment is intimately related to the water resources, it is essential to evaluate the water availability and related issues. This study applies statistical methods to analysis the streamflow data trend and break point in the basins of the northern Taiwan, including Lanyang River, Keelung River, Dahan River, Femgshan River, Youluo River and Shangping River. Furthermore, the Budyko-Fu equation and the Budyko-Mezentsev-Choudhury-Yang equation are applied to evaluate the elasticity coefficient of climate and catchment characteristics parameter, which can provide sensitivity analysis of streamflow to rainfall, potential evapotranspiration and catchment characteristic parameter, and quantifying the streamflow change due to the impact of climate change and human activities. The results show that the break points of streamflow data in Lanyang River and Keelung River were detected in 1993 and 1990 respectively. The streamflow of Lanyang River increased by 32.50% during the impacted period, about 109.00% of the variation was caused by non-climate factors; the Keelung River was reduced by 18.11% during the impacted period, and the dominant factor was climate change, accounting for 71.53% of reduction. Result of Sensitivity analysis showed that precipitation changes was the most sensitive factor of streamflow variation. For every 1% increase in precipitation, the streamflow would increase by 1.05% to 1.37%. These results could serve as reference for the sustainable development of water resources and territorial policies in the northern Taiwan.