This report investigates the long-term morphological changes caused by the DELTA 21 project at the northern side, including the large scale morphological development with Delft3D model and at local scale the coastline deformation with UNIBEST-CL model. The necessity of the layout design improvement of DELTA 21 is analyzed by comparing different results in case of the improved layout and the original layout. On local scale, the model results indicate that shoreline retreat will happen around the head of Valmeer and large amount of sediment is lost in that section in case of both original layout and improved layout. And the improvement in the layout of DELTA 21 project has remarkable influence on coastline evolution and sediment balance. On large scale, a scour hole near the most western location of the Valmeer and a large submerged sand bar at the northern side of Valmeer are developed after 20 years. In case of original layout, the scour hole gives a larger maximum depth. It can be concluded that the improved layout of DELTA 21 gives better performance on both large scale and local scale.