Plain reservoirs are shallow, and have low dams and widespread water surfaces. Therefore, wind-wave-induced damage to the dam is one of the important factors affecting the safety of the reservoir. To improve upon unsatisfactory plain reservoir wave-clipping schemes, a numerical method is proposed to predict and analyze waves in the reservoir in the presence of artificial islands, constructed from dredged sediment. The MIKE21 SW model is applied to a specific plain reservoir for finding the optimal artificial island parameters. The simulated wave height attenuation results are seen to agree well with empirically predicted values. Thus, the validity and reliability of the numerical model are established. Artificial islands at suitable locations in the reservoir can attenuate the wave heights by approximately 10％e30％, which justifies the efficacy of the clipping scheme making use of dredging and island construction.