| The rapid economic development promotes the protection of cultural relics in Mogao grottoes.This thesis is based on the program of "Key technology research on risk monitoring and evaluation in Mogao grottoes, Dunhuang".On the basis of original protection measures in the Mogao grottoes, a set of system protection scheme was introduced to supplement the vacancies of protection and researches in original part field and establish complete risk early warning system of Mogao grottoes,which was from the perspective of the cultural relics’micro-environment and the the surrounding environment’s protection.In order to build a corresponding mode of Mogao grottoes area rainfall and flood., Mogao grottoes area flood risk was mainly studied in this paper.Mogao grottoes is in the basin of Daquan River, and the Daquan River is lack of rainfall and flood monitoring data. The historical flood data is mainly the peak flow, most of which are calculated according to the flood trace and the characteristics of monitoring section after the flood without enough corresponding rainfall data. There are a small amount of rainfall data about river basin and its adjacent area,which can be used to calculate design storm of Daquan River.In order to study the relation between Daquan River basin’s rainfall and Mogao grottoes’ flood from the perspective of physical cause of the flood about rainfall, Haobulege Village,Mahuanggou Gobi and the top of Mogao grottoes were selected as representative sites to be carried out field artificial rainfall simulation experiment to study the laws of runoff generation and confluence.The results show:the laws of runoff generation and confluence in Daquan River basin are similar with the study results in Hexi district,Gansu province.Therefore, Daquan River basin runoff generation and confluence calculation can refer to the calculation method of Hexi district,the parameters can be adjusted appropriately according to the result of rainfall experiment and watershed characteristics. The methods of the early loss deduction by stages and average infiltration rater on runoff generation period were used to calculate runoff generation, instantaneous unit line method was used to calculate confluence. Origin software is used to analyze the relationship between the flood peak and its corresponding rainfall characteristics,which is the calculation empirical mode of flood peak flow,and the rainfall characteristics includes average net rainfall intensity, the maximum rainfall intensity and rainfall runoff in rainfall runoff generation duration.The correlation between the flood peak flow and rainfall characteristics in river upstream, midstream and downstream are respectively considered. Studies show :rainfall characteristics of Daquan River basin is close to the flood peak flow.Considering maneuverability of empirical mode in the engineering practice, the fitting relation between rainfall runoff generation and flood peak flow is chose as the region’s flood peak flow calculating empirical mode. The empirical modes adapting upstream, midstream and downstream are respectively:Qup=-23.21+5.87xHup; Qmid=0.35+3.79×Hmid; Qdown=-54.68+ 15.86×Hdown.The flood of Mogao grottoes in Daquan River basin is the superposition of three sections of the flood,the flood peak flow calculating formula of Mogao grottoes section is QMo=0.90(-23.21+5.87×Hup)+0.88(0.35+3.79×Hmid)+ 0.21(-54.68+15.86×Hdown). |
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