Assessing marine environmental carrying capacity in semi-enclosed coastal areas - Models and related databases

Faced with the degradation of the marine environment, the Joint Group of Experts on the Scientific Aspects of Marine Pollution (GESEMP) first presented the concept of marine environmental carrying capacity (MECC) in 1986, which confirmed that there is a need to pay attention to physical, chemical, biological, and biochemical processes, thereby indirectly suggesting the need for a modelling approach. Although studies on MECC have been published, further research is necessary and must be complemented by a new approach. In this study, an integrated system called SECAMECC (Marine Environmental Carrying Capacity Semi Enclosed for Coastal Areas) for semi-enclosed bays is proposed. SECAMECC comprises database of seven data groups and four models: 3D hydrodynamic, ecological, retention time estimation, and MECC calculation. The proposed system has been applied to a specific semi-enclosed bay as a case study to determine the MECC seasonally. The carrying capacities of ammonium (NH₄⁺), phosphate, total suspended solids (TSS), and biological oxygen demand were assessed in accordance with the baseline and forecast scenarios. The received results show that under the baseline, MECC no longer accepted PO₄^3-; meanwhile, NH₄⁺, TSS, and BOD₅ exhibited the following values in the dry and wet season, respectively: 1134 and 3514 (t/m); 110,578 and 144,458 (t/m); and 17,072 and 44,348 (t/m). Owing to the hydrodynamic factors, the carrying capacity in the dry season is always greater than that in the wet season. Furthermore, the relationship between MECC and environmental standards, current water quality, and hydrodynamic factors was clarified.