Abstarct: Being joined to land on one end and to the sea on the other in the direction of dominating waves and large shore currents, Spits are beach phenomena/materials that grow with time gravitating towards the land in one or several branches. Of the most stand-out spits in Iranian seas, the sandy narrow peninsula called Miankaleh comes to mind, which is the main cause in the formation of Gorgan gulf. Current research mainly pursues the investigation of the changes occurred in the shores of Miankaleh spit under the influence of water level changes. To this end, first, analytical theories associated with the area of interest were investigated and the results were compared with satellite images for final verification. In the next step, employing the mike 21 numerical model, the impact of changes to the water level on the various parts of the Miankaleh spit was evaluated. The result of an experimental relation shown in this research speaks of a 110-meters change in shorelines per assumed one-meter change in the water level. In addition, results obtained from numerical imitation demonstrates that the changes in shorelines are in accordance with hydrodynamic circumstances dominating the shore – including the properties of wave and current - and morph dynamic circumstances dominating every single part of the Miankaleh spit including the shape of bed, shore slope, type of sediments and changes to the equilibrium depth, in a way that in eastern parts in the vicinity of the opening of Gorgan gulf, as the water level decreases shoreline moves more than the middle and western parts towards the sea. Given the results of the theoretical relations and conducted modeling, investigating various states dominating the shore in three west, east and middle regions shows that the state of the shore in all the regions is dissipative, which by moving from west to east the dissipatedness increases, leading to shoreline moving further head by decreasing water level.