The Sepulveda Sea Wall was located in Los Angeles
Due to the rising oceans in the world of 2049, Los Angeles faced flooding and eventual annihilation without some way of stopping the sea levels from affecting the city. Thus, the Sepulveda Sea Wall was constructed to prevent this catastrophe.
On the way to theOff-world colonies to torture Deckard on the whereabouts of his child and the location of the replicant resistance movement, Luv and a couple of escort spinners flew above the sea wall towards LAX, now a spaceport. K intercepted them and shot down all three vehicles, and engaged in a fight with Luv when her spinner crashed where the wall met the ocean.
The waves nearly destroyed the spinner and drowned Deckard until K finally overcame and killed Luv, saved Deckard, and swam back to the base of the wall before taking Deckard to his daughter.
- The name Sepulveda Sea Wall comes from a collider article describing what happened between 2019 and 2049:
"When we return to Los Angeles, 30 years after the original movie, climate change has caused the sea level to rise dramatically. A massive Sea Wall has been built along the Sepulveda Pass to protect the Los Angeles basin."
The official Blade Runner 2049 art-book The Art and Soul of Blade Runner 2049 also discuss the Sepulveda Sea Wall.