Why does the Tsauchab River end at Sossusvlei instead of reaching the Atlantic Ocean?

The Tsauchab River, which originates in the Naukluft Mountains, historically flowed to the Atlantic Ocean. However, it no longer reaches the coast because its path has been blocked and dammed by the formation of massive sand dunes.1

These dunes are part of the Namib Sand Sea and were created over millions of years by wind-blown sediment from the coast, the interior of Africa, and dry riverbeds, including the Tsauchab’s own bed. Because the Namib is an arid region with a poorly developed drainage pattern, many streams in the area terminate in a vlei (a salt pan or mud flat) rather than reaching the sea. Consequently, the Tsauchab now terminates at Sossusvlei, where the riverbed is obstructed by the surrounding dune fields.123