Comments on “Simulation of Jeddah multi–port sea outfall” by Abdullah S. Al-Ghamdi [J. Coast. Conserv.] (2010) 14:63–69

In a paper published recently in the Journal of Coastal Conservation, Al-Ghamdi (J Coast Conserv 14:63–69, 2010) analyzes the wastewater multi-pot outfall of Jeddah using CORMIX2 for average ambient conditions. Both the near–field and the far–field mixing are calculated with CORMIX2. It is found in Al-Ghamdi (J Coast Conserv 14:63–69, 2010) that the near-field extends 187.5 m downstream from the diffuser, where the dilution reaches 1,047.8. It is at this same distance, 187.5 m, that the plume touches the water surface. The far-field dilution and plume width is calculated as the plume finally fills the entire water depth at a distance of 18,927 m downstream. From these analyses, it is concluded that local and international standards for treated wastewater are met and that the plume “will not pose any treats to the local venerable environment”. These findings, if correct, will help to protect the surrounding marine environment. However, is argued here that the use of CORMIX2, particularly for the far-field environment is not well justified and that the inherent simplifications in the software and its use, mainly the characterization of the physical environment, undermine the main conclusions.