Study On The Non-stationary Of Hydrological In Yellow River Basin Under Changing Environment

Under the influences of climate change and human activities,the Yel ow River basin is greatly affected,which have triggered many times of the Yel ow River's cut off,increased evapotranspiration in the river basin,and frequent occurrence of flooding phenomena.This has also had a certain influence on the accuracy and fit of design values of water conservancy projects,civil engineering projects,and so on.Consistency hypothesis theory is chal enged,results of hydrological inconsistency studies based on the consistency hypothesis theory,and hydrologic frequency calculations have been questioned.In order to test the inconsistency and evolution of rainfall and evaporation sequences in a changing environment,the GAMLSS model was used to study the inconsistency of precipitation and evaporation in the Yellow River Basin(all rainfall and evaporation data are surface data in this paper).Taking into account the regional differences and interannual variations of the river basin,the Yel ow River Basin is divided into 29 tertiary areas,the rainfall and evaporation of the Yel ow River Basin are studied from three perspectives of the year,flood season,and non-flood season.A total of 318 hydrological stations were selected from 310 hydrological stations in the Yel ow River Basin and 8 hydrological stations near the basin.The daily rainfall data from 1961 to 2010 was taken as the basic data for the non-stationary of the annual rainfall sequence,flood season,and non-flood rain series in the Yellow River Basin.The law of evolution was studied.The Yelow River Basin's 95 nearby meteorological stations were selected,including 90 meteorological stations in the basin,3 meteorological stations near the Jindi River and natural Wenyan Canal,and 2 meteorological stations near the downstream of the Huayuankou.The daily evaporation data from 95 meteorological stations from 1963 to 2013 were used as the basic data to study the non-stationary evolution of annual evaporation,evaporation in the flood season,and evaporation in the non-flood season in the Yellow River Basin.In this paper,Kendall rank correlation test method was used to test the trend of precipitation and evaporation in the basin.Mann-Kendall test method and sliding t test method were used to test the abrupt changes of precipitation and evaporation in the Yellow River Basin.Using time as an explanatory variable to fit the annual,flood,non-flood rainfall and evaporation sequences of each tertiary region of the Yel ow River Basin,the precipitation and evaporation sequences of the Yel ow River basin were fitted using the GAMLSS model to obtain the characteristics of non-stationary rainfall changes.The main research results of the paper are as follows:(1)Results of the trend test: The precipitation and evaporation of the 29 tertiary areas in the Yellow River Basin mainly showed a downward trend,and some of the tertiary areas showed an upward trend.There are more tertiary regions with more significant changes in evaporation,and the statistics and trending values of the evaporation series in the annual,flood,and nonflood seasons are greater than those in the corresponding tertiary regions under the corresponding period.The results of the mutation test showed that there were more tertiary regions where the amount of evaporation mutated;the abrupt change points of rainfall were concentrated in the vicinity of 1975;the abrupt change points of evaporation in the summer and flood seasons were concentrated in the vicinity of 1995;the evaporation in the non-flood season was concentrated in 1976-1985.(2)There are inconsistencies in both rainfall and evaporation in the Yel ow River Basin.The fitting effect of the non-stationary model in some tertiary regions was better than that of the stationary model.The improvement range of the evaporation and rainfall fitting results was different,and the improveme nt of the evaporation in the year,flood season,and non-flood season was significant.The characteristics of inconsistency of evaporation in the Yellow River Basin are obvious,and the rainfall does not show obvious non-stationary.There are many tertiary areas with inconsistent evaporation characteristics,indicating that the probability of non-stationary of evaporation in the three levels of the Yellow River Basin is higher.(3)The three-level region with non-stationary characteristics in the three-level region and the GAMLSS model fitting results of the rainfall and evaporation trend test are highly significant,indicating that there is a certain relationship between the trend test results and the GAMLSS model fitting results.