The detention rock ll dams are of crucial signi cance in engineering ood control projects due to their minimal technical requirement, low cost, minimal environmental effects, self-automotive operation process. However, the reliable design of detention rock ll dams is a challenging topic because of the complex interaction between the coarse porous rock ll material and the ow, the non-Darcian ow in rock lls, their stability encountered with oods, reliable ood peak reduction, and safe ood discharge release to the downstream. The present study aims to investigate and evaluate the in uence of aleatory uncertainties (i.e., rock ll material, hydrologic, hydraulic and geometric uncertainties) in the reliable design of detention rock ll dams. In this study a reliable design framework of detention rock ll dams is developed with a focus on the importance of stability of rock ll dams against the oods. The developed framework is used to acquire future detention rock ll dam design and modeling requirements. The stability analysis, neglected in previous literature of rock ll dams, is performed under the uncertain design parameters. The uncertainty of input parameters in model design consideration is investigated including the uncertainties of inlet hydrograph, volume-elevation relation of reservoir, non-Darcian stage-discharge equation in coarse rock ll material, non-linear ood routing in detention rock ll dams. The effects of design uncertainty sources on the stability of dam, safety factors of overturning, sliding and bearing, along with the hydraulic performance of the dam were tested. The results in the present study revealed that the uncertainties in the input parameters of the model can effectively produce uncertainties in the hydraulic performance of detention rock ll dams ranges from − 53.54 to + 110.11 percent. Finally, the effects of input uncertainties on the structural stability and safety factors in detention rock ll dams is investigated. The results revealed the safety factor against the sliding (SFS) has maximum dependencies with the uncertainties ranging − 32.63 to 87.81 percent. Using the Monte-Carlo Simulation (MCS) and tting probability distribution functions to the safety factor histograms, the best PDF is selected by the goodness of tting tests to determine the improvement percentages in safety factors. The MCS and uncertainty quanti cations results in 88.3 percent in increasing the safety factors as a reliable methodology for stability design of detention rock ll dams. Thus, the study calls for reliable, certain and safe design of ood protection rock ll ponds.