摘要：The flood peak and flood volume are generallyconsidered to be independent random variables in early-termdam construction diversion risk simulation, while thecofferdam elevation is a definite value. Due to the continualconstruction of high dams at the 200 m-level in southwestChina, the effect of flooding on dams lasts longer than beforedue to greater filling volumes and longer construction periods.The correlation between the flood peak and the volume hasbeen shown to affect the accuracy of mid-term diversion riskanalysis. Aiming at determining the mid-term diversion risk ofhigh rockfill dams, this paper presents a joint distribution forthe construction flood peak and volume using the copulafunction. Then, a simulation model for the monthly fillingheight during the flood season is given considering the fillingintensity and effective construction days, in which the dailyrainfall and the stoppage standards for rain, which affect theeffective construction days, were analysed. Additionally,stochastic factors such as the hydrology, hydraulics, stop days,and filling intensity were considered to resolve the diversionrisk rate by using the Monte Carlo method. Finally, an exampleof a high rockfill dam in southwest China was provided to verifythe correlation between the flood peaks and volumes and tocalculate the mid-term diversion risk during its construction byincorporating historical flood data, rainfall days, and diversionstandards. The results reflect the probability distribution of aconstruction flood more accurately, avoiding the overestimationof a low-probability flood event, with a high peak but a smallvolume, that leads to a lower risk rate and lower designedreliability for diversion structures. In addition, the monthlydiversion risk and its corresponding maximum water level inthe equivalent reappearance period can provide designreferences for coordination between flood prevention measuresand construction schedules.
