|Assessment of changes in water balance components under 1.5 ◦C and 2.0 ◦C global warming in transitional climate basin by multi-RCPs and multi-GCMs approach
|Hao, Y., J. Ma, J. Chen, D. Wang, Y. Wang and H. Xu
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|extreme low and/or high flows/events
|13,846 km^2 Chaobai River, which drains parts of Hebei, Beijing and Tianjin Provinces in northeast China.
|The global warming of 1.5 ◦C and 2.0 ◦C proposed in the Paris Agreement has become
the iconic threshold of climate change impact research. This study aims to assess the potential
impact of 1.5 ◦C and 2.0 ◦C global warming on water balance components (WBC) in a transitional
climate basin—Chaobai River Basin (CRB)—which is the main water supply source of Beijing.
A semi-distributed hydrological model SWAT (Soil and Water Assessment Tool) was driven by climate
projections from five General Circulation Models (GCMs) under three Representative Concentration
Pathways (RCPs) to simulate the future WBC in CRB under the 1.5 ◦C and 2.0 ◦C global warming,
respectively. The impacts on annual, monthly WBC were assessed and the uncertainty associated
with GCMs and RCPs were analyzed quantitatively, based on the model results. Finally, spatial
variation of WBC change trend and its possible cause were discussed. The analysis results indicate
that all the annual WBC and water budget are projected to increase under both warming scenarios.
Change trend of WBC shows significant seasonal and spatial inhomogeneity. The frequency of flood
will increase in flood season, while the probability of drought in autumn and March is expected to
rise. The uneven spatial distribution of change trend might be attributed to topography and land use.
The comparison between two warming scenarios indicates that the increment of 0.5 ◦C could lead to
the decrease in annual surface runoff, lateral flow, percolation, and the increase in annual precipitation
and evapotranspiration (ET). Uncertainties of surface runoff, lateral flow, and percolation projections
are greater than those of other components. The additional 0.5 ◦C global warming will lead to larger
uncertainties of future temperature, precipitation, surface runoff, and ET assessment, but slightly
smaller uncertainties of lateral flow and percolation assessment. GCMs are proved to be the main
factors that are responsible for the impact uncertainty of the majority assessed components.
|water balance components; RCPs; GCMs; assessment; 1.5 ◦C and 2.0 ◦C global warming