To quantitatively evaluate the characteristics of runoff wetnessdryness encountering and their impacts under different water diversion schemes for the SouthtoNorth Water Diversion Western Route Project, this study focused on three main water dive〖JP2〗rsion schemes. A runoff wetnessdryness joint distribution model at the upper and lowerline sections was constructed based on the Vine Copula function, and the runoff wetnessdryness encountering characteristics under each water diversion scheme were analyzed. Furthermore, a water diversion adaptability index was proposed, and an analysis of the probability of favorable water diversion conditions was conducted to explore the impacts of different schemes on the overall effectiveness of the Western Route Project from a multidimensional perspective. The results showed that, for scheme 1(with the upper and lower route intakes of 8 billion m3 and 9 billion m3, respectively), the synchronous wetnessdryness encountering probability was 52.0%, exceeding the asynchronous probability. Its water diversion adaptability fluctuated significantly, ranging from 56.3% to 66.0%. The favorable water diversion probability was the lowest at 62.3%, and its water diversion stability was poor. For scheme 2 (with the upper and lower route intakes of 4 billion m3 and 13 billion m3, respectively), due to an increased number of sections, the synchronous wetnessdryness encountering probability decreased to 47.8%. It exhibited superior performance to scheme 1, with water diversion adaptability ranging from 68.3% to 74.9% and a favorable water diversion probability of 63.3%. Scheme 3 (with the lower route intake of 17 billion m3) had a synchronous wetnessdryness encountering probability of 50.4%, approximately equal to the asynchronous probability. Its water diversion adaptability was optimal, reaching a maximum of 76.0% with the smallest fluctuation. The favorable water diversion probability for scheme 3 was the highest at 69.3%. Consequently, scheme 3 can more effectively utilize the runoff resources between sections and is more conducive to ensuring the overall stability of the project.