Zhuge Liang's life is expressed in a couplet, in which what does "three rivers" mean?

This is a couplet of Wuhou Temple in Chengdu, which describes Zhuge Liang's great achievements in his life. The couplet is like this: close the two rivers, arrange eight arrays, catch six out of seven, light forty-nine lights before five feet, and concentrate on three concerns; Take western Shu, gather people from the south, and reject things from the north. In Zhong Jun's records, Jin Mu's divination was changed, and the water surface could be attacked by fire. "Receiving Erchuan" refers to the recovery of Dongchuan and Xichuan, and refers to Liu Zhang and Zhang Lu; "Arranging eight arrays" refers to creating eight arrays; "Seven capture six" refers to six out of Qishan and seven capture Meng Huo. "Forty-nine lights were lit in front of Wuzhangyuan, and one heart was only concerned about three things", referring to the last time I was sick, I held a prayer ceremony in front of Wuzhangyuan, hoping that God could continue his life and complete the great cause of cutting Wei. As a result, Wei Xiang reported the military situation and knocked over the main light. This should be Zhuge Liang's life, and he will do his best in the end. "Take West Shu and conquer Nan Man" means taking Xichuan, making Chengdu its capital, conquering the south and pacifying Meng Huo's rebellion, which is the submission of the barbarians. "Rejecting the East and the North" refers to Zhuge Liang's policy of "uniting Sun Quan in the East and resisting Cao Cao in the North". "In Zhang Zhongjun, Jin Mu's divination was changed" means that Zhuge Liang is proficient in the five elements and can strategize. "Fire hits the water" refers to Battle of Red Cliffs designed by Zhuge Liang. He set fire to Cao Cao on the Yangtze River and wiped out 830,000 Cao Jun.