Abstract
Landslides, debris flows, and other secondary disasters caused by earthquakes threaten the safety and stability of river basins. Earthquakes occur frequently in Japan. Therefore, it is necessary to study the impact of earthquakes on sediment transport in river basins. In this study, considering the influence of reservoirs, the Soil and Water Assessment Tool-calibration and uncertainty program (SWAT-CUP) was employed to analyze the runoff parameter sensitivity and to optimize the parameters. We manually corrected the sediment transport parameters after earthquake, using the Soil and Water Assessment Tool (SWAT) model to assess the process of runoff and sediment transport in the Atsuma River basin before and after the 2018 Hokkaido Eastern Iburi Earthquake. The applicability of the SWAT model to runoff simulation in the Atsuma River basin and the changes of sediment transport process after the earthquake were studied. The research results show that the SWAT model can accurately simulate the runoff process in the Atsuma River basin, the Nash–Sutcliffe efficiency coefficient (NSE) is 0.61 in the calibration period, and is 0.74 in the verification period. The sediment transport increased greatly after the earthquake and it is roughly estimated that the amount of sediment transport per unit rainfall increased from 3.5 tons/mm/year before the earthquake to 6.2 tons/mm/year after the earthquake.
Highlights
Global climate change has caused natural disasters to occur frequently [1,2,3], it is important for human beings to adapt and respond to disasters [4]
Determining the most sensitive parameters for reproducing runoff were Snow pack temperature lag factor (TIMP), Curve number (CN2), Melt factor for snow on 21 December (SMFMN), Melt factor for snow on 21 June (SMFMX), Temperature lapse rate (TLAPS), Available water capacity (SOL_AWC), Snow melt base temperature (SMTMP), Effective hydraulic conductivity in main and tributary channel alluvium (CH_K2, CH_K1), Minimum snow water content that corresponds to 100% snow (SNOCOVMX), Manning’s “n” value for the main and tributary channel (CH_N2, CH_N1), Soil evaporation compensation factor (ESCO), Precipitation lapse rate (PLAPS), and Snowfall temperature (SFTMP)
The most sensitive parameters for reproducing runoff were Snow pack temperature lag factor (TIMP), Curve number (CN2), Melt factor for snow on 21 December (SMFMN), Melt factor for snow on 21 June (SMFMX), Temperature lapse rate (TLAPS), Available water capacity (SOL_AWC), Snow melt base temperature (SMTMP), Effective hydraulic conductivity in main and tributary channel alluvium (CH_K2, CH_K1), Minimum snow water content that corresponds to 100% snow (SNOCOVMX), Manning’s “n”
Summary
Global climate change has caused natural disasters to occur frequently [1,2,3], it is important for human beings to adapt and respond to disasters [4]. From 2017 to 2019, a total of 332 earthquakes with intensity of 6 or more occurred globally, including 35 earthquakes with intensity of 7 or more and 2 earthquakes with intensity of 8 or more [5]. The process and mechanism of gravity erosion in river basins after an earthquake are complicated, gravity erosion usually occurs randomly, and it combines with hydraulic erosion. They have a significant effect on runoff, sediment production, and sediment transport. Processes and mechanisms are hotpots in the research fields of debris flow, soil erosion, and river sediment transport [8]
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