The Role of Climate Change and Human Factors in Affecting Runoff and Hydrological Drought Characteristics of a Watershed

The main objective of the study is to evaluate the roles of climate change and human factors on runoff, baseflow, and hydrological drought characteristics at a watershed scale. The novelty of the study is to assess separately the cascading, indirect, accumulative effects of climate change and human factors on hydrological drought, i.e. runoff and baseflow. This involved analyzing change points to divide the available hydrometeorological data into a baseline and a perturbed period. We applied two hydrological models, SWAT and HBV-light, and two nonparametric climate elasticity of runoff to identify the contribution of climate change and human factors in influencing runoff and baseflow processes. The hydrological models were used to simulate naturalized runoff and baseflow during the perturbed period. The temporal variation in the characteristics of the baseflow regime is expressed as baseflow index. Drought indices, standardized runoff index and standardized baseflow index were used as hydrological drought indicators. A significant change in runoff reduction in the Kamienna watershed began in 1982, suggesting that human factors play a dominant role in influencing runoff. In addition, we found that an increase in baseflow and a decrease in hydrological drought events in the 2010s are a positive long-term effect of human factors such as construction of dams in the watershed. Finally, analyses of changes in land cover dynamics in the watershed over the past four decades using satellite imagery are used to confirm the presence of human interventions.