Quantifying climate and anthropogenic impacts on runoff using the SWAT model, a Budyko-based approach and empirical methods

ABSTRACT Understanding the impact of climate change and human activities on runoff is crucial for water resources management. However, an evaluation of available methods for analysing this impact is lacking. In this study, we comprehensively reviewed four commonly used quantitative methods: the Soil and Water Assessment Tool (SWAT) model, Budyko-based approach, and two empirical methods, i.e., Double mass curve (DMC) and Modified DMC (MDMC). Using the Wei River basin as a case study, we assessed the runoff reduction influenced by climate change and human activities from 1970 to 2017. The results show that human activities are the primary driver for runoff reduction. The highest contribution of human activities was estimated by the DMC (93.2%–99.9%), followed by MDMC and SWAT (65.6%–87.1%), while the Budyko-based had the smallest estimates (55.3%–61.2%). Each method has advantages and limitations, so the appropriate method should be selected based on research objectives and data availability/quality.