Response of hydrologic drought to meteorological drought in the Bayin River basin
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Abstract:
Drought is considered to be the most costly natural disaster,and it is repetitive.This disaster has a serious impact on agricultural production and life.Compared with other types of disasters,it has a wide range,long impacted,large losses,and spreading trends.Since 1990s,drought in China has become more serious and frequent.According to the differences of water-affected objects in different links of the water cycle,drought is generally divided into meteorological drought,hydrological drought,agricultural drought,and socio-economic drought.The occurrence of different types of drought has a progressive relationship in time.Meteorological drought is the root of other drought types and plays a key role in the transmission chain of drought disasters.The occurrence of hydrological drought is slower than that of meteorological drought,and its duration is longer than meteorological drought.The occurrence of meteorological drought is generally difficult to control,but the impact of hydrological drought can be avoided or reduced through certain measures.In the research on the transmission of different types of drought,the analysis of the characteristics and spatial distribution of specific types of drought in the basin are focused on.In the analysis process,a single drought index is selected to discuss the drought situation. Losses are caused by the evolution of different types of drought. In order to reduce the occurrence of such phenomena,meteorological drought and hydrological drought will be analyzed by calculating the standardized precipitation index (SPI) and standardized runoff index (SRI) for the monthly precipitation and monthly runoff of Delingha station from 1961 to 2019.The Mann-Kendall test will be used to used to evaluate drought trends.The propagation time between meteorological drought and hydrological drought and the seasonal response of hydrological drought to meteorological drought will be studied in this paper to explore the possible influence and driving factors of meteorological drought on the spread of hydrological drought. The results show that there are obvious differences in the standardized precipitation index (SPI) values at different time scales,but the drought trend is roughly the same.The fluctuation of the monthly scale (SPI1) is the strongest,and the fluctuation slows down with the increase of the time scale.The results of SRI have similar characteristics to meteorological drought.The fluctuation range of SRI value under different time scales is different,but the drought trend is roughly the same.The fluctuation of SRI1 is the strongest,which shows that the smaller the time scale,the stronger the SRI response to hydrological drought.From 1961 to 2019,the meteorological drought and hydrological drought in Bayin River basin showed a slowing trend,the precipitation in the basin increased and tended to basin become wet.The meteorological drought situation in the basin was the most severe in the 1960s,showing moderate to severe drought on the whole.There was a sudden change in meteorological drought in 1985,and then the wet years in the basin increased significantly.The hydrological drought in the basin was more serious in the 1990s,showing a moderate to severe drought state.Hydrological drought has rarely occurred in the basin since the 21st century.Mann Kendall trend test results show that the abrupt change point of hydrological drought in the basin is 2002,and the number of years showing a hydrological humid state has increased since 2002.The correlation between hydrological drought and meteorological drought in the Bayin River basin is the strongest on the 12-month scale.The time lag cross-correlation analysis of meteorological drought index and hydrological drought index on the 12-month scale shows that the response of [JP2]hydrological drought to meteorological drought in Bayin River basin shows time lag,and the hydrological drought lags behind the meteorological drought for 1-2 months.The seasonal response of hydrological drought to meteorological drought shows that the correlation intensity of the rainy season is higher than that of the dry season.Hydrological drought responds most rapidly to meteorological drought in spring.The response of hydrological drought to meteorological drought in spring and summer is faster than that in autumn and winter.The seasonal response of hydrological drought to meteorological drought lags 5,6,9,and 8 months in spring,summer,autumn and winter.On the whole,The lag time in spring and summer is shorter than that in autumn and winter. This shows that timely detection and corresponding measures in the meteorological drought stage can effectively prevent the further development of meteorological drought into hydrological drought.Because the hydrological drought in Bayin River basin responds quickly to meteorological drought in spring and summer,more attention should be paid to the drought state of the basin in the rainy season.Although the Bayin River basin shows a wetting trend during the study period,the prevention and control of drought in the Bayin River basin are still worthy of attention in the northwest inland area with a lack of water resources.In the context of global warming,considering the continuous rise of temperature,evapotranspiration will become an important part of the future.In addition,with the gradual improvement and operation of water conservancy projects,the impact of future human activities will also aggravate the impact of the water cycle in the convective domain.Therefore,it will become one of the important directions of watershed hydrological research to select the comprehensive drought index from the perspective of ecology and social economy,carry out multi-factor comprehensive analysis,and reasonably simulate the increasingly complex hydrological process to provide a more perfect drought risk assessment.
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