Abstract
Global warming and land-use change affects runoff in the regional basin. Affected by different factors, such as abundant rainfall and increased impervious surface, the Taihu basin becomes more vulnerable to floods. As a result, a future flood risk analysis is of great significance. This paper simulated the land-use expansion and analyzed the surface change from 2020 to 2050 using the neural network Cellular Automata Markov (CA-Markov) model. Moreover, the NASA Earth Exchange Global Daily Downscaled Climate Projections (NEX-GDDP) dataset was corrected for deviation and used to analyze the climate trend. Second, the verified SWAT model was applied to simulate future runoff and to analyze the future flood risk. The results show that (1) land use is dominated by cultivated land and forests. In the future, the area of cultivated land will decrease and construction land will expand to 1.5 times its present size. (2) The average annual precipitation and temperature will increase by 1.2% and 1.5 degrees from 2020 to 2050, respectively. During the verified period, the NSE and r-square values of the SWAT model are greater than 0.7. (3) Compared with the historical extreme runoff, the extreme runoff in the return period will increase 10%~25% under the eight climate models in 2050. In general, the flood risk will increase further under the climate scenarios.
Highlights
With the progress of global warming, temperature has risen in most basins of China and precipitation has become more uneven in the spatial-temporal distribution
According to the land use calculated by the cellular automata (CA)-Markov model, it can be seen that the construction land shows a clear growth trend from 2030 to 2050
The average annual precipitation and temperature will increase by 1.2% and 1.5 degrees, respectively, from 2020 to 2050
Summary
With the progress of global warming, temperature has risen in most basins of China and precipitation has become more uneven in the spatial-temporal distribution. The rapid changes in climate have caused increasingly prominent water problems, such as floods and drought, which can bring about a series of ecological, environmental, and social security problems [1]. Human interference, which influences river streams and floodplains, is a cause of flash flood generation [2]. Because of the upper mountains, lower plains, and intensified human activities, the Tiaoxi basin has become a flood-prone area. There were six flood events from 1999 to 2018, two-thirds of which were caused by strong typhoons, and one-third caused by continuous heavy rainfall in the Tiaoxi basin.
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