Abstract: The Friendship port (port of Nouakchott) in Mauritania is located on the east coast of the Atlantic Ocean, a typical sandy beach having mean sediment diameter 0.25 mm. Tidal currents are weak, while strong longshore transport from the north to the south induced by wave actions plays a main role in sediment movement. Previous studies show that the annual longshore sediment transport was about one million cubic meters. The construction of the port intercepted longshore sediment transport, which caused serious upstream accretion and downstream erosion and changed the original straight coastline. To protect the yard from erosion, a groin on the south side of the port was built in 1991. The erosion reached the end of the groin in 2009, and endangered once again the safety of the yard and other land facilities. According to the measured shoreline data, a “one-line theory” mathematical model was used to calculate shoreline evolutions for different protection schemes of the south coastline. T-shape groin was planned to build in the shore, where the transverse part can keep upstream sediment and prevented the head of the groin from wave attacks. The transverse part was 300 m long and was put along -2 m contour. Numerical modelling results show that the coastline between the new T-shape groin and the existing groin was soon adjusted to steady state and was fixed in position. The recommendation scheme for the south coastline prevention was to build a new T-shape groin 2 000 m downstream of the existing groin, which was implanted by the port authority in 2013. Due to strong longshore sediment transport, the new shoreline protection works fix upstream shoreline, while their downstream shoreline erosion is inevitable. Taking a longer duration and a greater range of shoreline stability into concern, new protection measures are needed every certain number of years.