Salinity gradient energy (SGE) is the energy that can be obtained from the mixing entropy of two solutions with a different salt concentration. This energy could be used for electricity production by some methods (e.g. Reverse Electro-Dialysis (RED); Pressure Retarded Osmosis (PRO) … , etc.). Estuaries or Delta, as zones for mixing of fresh water from rivers and saltwater from the sea, has a large power potential of this renewable energy. The aim of this study is to investigate the effects of two parameters namely: Flushing Time (FT) and Intrusion Length (IL) on energy potential due to salinity gradient of the selected estuary, i.e. Sebou estuary (Morocco) (i.e. is used as an application site), the energy calculation is based on thermodynamic equations. The results showed that both parameters (FT and IL) have a significant influence on the salinity gradient energy (SGE). According to the calculation done at High Water Slack (HWS) condition, and the average river discharge in the Sebou estuary, the IL range from 11.5 to 53.9 km at HWS. In addition, the FT varies from 2.6 to 13.9 days for a river discharge ranges from 13 to 166 m3s−1. The effects of these parameters were to reduce the amount of extractable energy from salinity gradient energy as can be seen in the estuary. For an interval of 13.9 days at HWS, salinity gradient energy decreases 14.3%. May be these results can used as a starting point to determined an optimal intake points related to the design of a PRO or RED system in the estuary system.