Why did Liang give up the plan of diverting water from the Yellow River to Sichuan to develop irrigated land?

1957 12 13. Liang Zeng, director of Dingxi Agricultural Capital Construction Bureau, made a plan to divert the Yellow River water to Hanpingchuan, Jingyuan County to develop irrigation land. However, Lao Chen, who was in charge of the survey, later reported to Liang that according to the water level elevation, the canal line leading the Yellow River to Hanpingchuan must pass through the urban area of Lanzhou, which is theoretically impossible. Liang had to give up the plan.