The impacts of climate variability and human activities on streamflow change at basin scale

Human activities (HA) and/or climate variability (CV) may be two major factors impacting natural flow regime (NFR). This study was conducted following two objectives. The first was to develop scenario-based hydrological modeling (SBHM) to disentangle the natural and human-induced impacts on flow regime. The second objective was to quantify the interaction between temperature and precipitation for the assessment of CV. To do so, six scenarios were defined to evaluate either the impact of HA, CV or both. Four major results were achieved: (1) the interaction between temperature and precipitation was more prominent in basin upstream areas, which reduced the streamflow by 9% in the entire simulation period; (2) when separating the effects of climatic and human factors, SBHM results in comparison with those of the climate elasticity analysis showed no significant differences; (3) HA were the main force driving the streamflow reduction in the study basin; (4) a 5 degrees C increase in air temperature in the future would lead to an increase of 1.6% in average annual streamflow, and 41% in peak runoff.