SB 9.15.21
viplavitam sva-sibiram
pratisrotah-sarij-jalaih
namrsyat tasya tad viryam
viramani dasananah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Because Kartaviryarjuna made the water flow in the opposite direction, the camp of Ravana, which was set up on the bank of the Narmada near the city of Mahismati, was inundated. This was unbearable to the ten-headed Ravana, who considered himself a great hero and could not tolerate Kartaviryarjuna’s power.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Ravana was out touring to gain victory over all other countries (dig-vijaya), and he had camped on the bank of the Narmada River near the city of Mahismati.