| In the context of climate change,the stability of the climate system has decreased,the global and regional water cycle systems have undergone profound changes,and the drought situation has become severe increasingly.As a major tributary of the Huai River Basin,due to drought the Shaying River has suffered severe losses in recent years.This paper uses the Shaying River Basin as the research area to analyze the evolution characteristics of the drought driving factors in the basin,and lays the foundation for the division of the hydrological model parameter rate and the verification period;using the meteorological data of twelve meteorological stations in the basin from 1961 to 2019 and 1961-Establish a SWAT model based on runoff data in 2014,and build a drought data support platform based on the SWAT model;use SPI,SRI and MSDI indexes to identify meteorological drought,hydrological drought and comprehensive drought,and analyze the evolution characteristics of drought;combine MSDI index with traditional univariate index Comparison of SPI and SRI shows the superiority of MSDI in identifying comprehensive drought;using K-S test method combined with graphic analysis to select the optimal marginal distribution function;using the root mean square error(RMSE)minimum criterion combined with graphic analysis to optimize the two-dimensional Copula function;using two-dimensional The Copula function calculates the"or"and"and"return periods of the Shaying River Basin,and analyzes the drought risk of the basin.The main contents of this article are as follows:(1)The annual precipitation,annual average temperature and annual runoff in the Shaying River Basin showed decreasing-increasing-decreasing,decreasing-increasing and decreasing trends respectively;the mutation years were in 1982,2001and 2003;the cycles were respectively 29a,28a and 10a.(2)The SWAT model was constructed based on the meteorological data from1961 to 2019 and the runoff data from 1961 to 2014,and the Nash coefficient Ens and the correlation coefficient R~2 were 0.67 and 0.68 at regular intervals(1963-2000),and the verification period(2001-2014)The Nash coefficient Ens and the correlation coefficient R~2 are 0.66 and 0.72 respectively,which are both greater than 0.5,indicating that the simulation effect is good and can provide data support for drought monitoring.(3)By comparing the seasonal MSDI index with the SPI and SRI indexes of the Shaying River Basin,it is found that the three have good consistency and strong correlation.Analyze the types and specific meanings of different drought situations represented by the MSDI index under different comprehensive drought scenarios to verify its superiority in characterizing drought.From the perspective of temporal and spatial evolution,analyze the meteorological,hydrological and comprehensive drought characteristics of the upper,middle and lower reaches of the Shaying River Basin.On the time scale:the drought duration in the upper,middle and lower reaches of the Shaying River Basin is more synchronized with the overall changes in drought intensity;on the spatial scale:the drought duration and the spatial distribution of drought intensity are similar overall.(4)Using the travel theory to identify the drought characteristics(duration,intensity)of the Shaying River Basin,select the optimal marginal distribution function through the K-S test method,and the optimal marginal distribution functions corresponding to the drought duration and drought intensity of each sub-basin are mainly exponentially distributed,The nuclear density is estimated to be mostly.The optimal Copula functions corresponding to the meteorological drought,hydrological drought and comprehensive drought sub-basins are mainly Frank,Gumbel and Clayton Copula respectively.In the upper and middle reaches of the Shaying River Basin,the meteorological drought risk is generally higher.The areas with higher hydrological drought are mainly distributed in the lower reaches of the basin,and the overall risk of comprehensive drought is higher. |
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