It depends which NCIS you are referring to. CBS broadcasts NCIS, NCIS: Los Angeles, and NCIS: New Orleans. NCIS is aired on Tuesdays 8/7c. NCIS: Los Angeles is aired on Mondays 10/9 c. NCIS: New Orleans is aired on Tuesdays 9/8c.
Whereas groins are built to change the effects of beach erosion, jetties are built so that a channel to the ocean will stay open for navigation purposes. They are also built to prevent rivermouths and streams from meandering naturally.
Sand dunes, which protect the coastline from storm winds and waves, are formed when waves carry sand to the beach, where the wind picks it up and blows it inland. Gradually, the sand piles up and plants such as sea oats begin to grow in it. The sea oats slowly cover the entire dune and protect it from erosion.