아산만 해역으로 방류수가 배출될 경우, 생태-유체역학모델을 이용하여 아산만 해역의 장기 수질변화를 예측하였다. 생태-유체역학 모델은 해수유동 시뮬레이션을 위한 다층모델과 수질시뮬레이션을 위한 생태계모델로 구성되어 있다. 생태-유체역학모델을 이용하여 아산만해역의 장기 수질을 예측한 결과, 5개 정점에서 화학적산소요구량, 용존무기질소 및 용존무기인의 농도분포는 현재 계산결과에서 6개월 동안 증가하였다. 수치실험 수행시간 1년에서 2년 사이에서는 화학적 산소요구랑, 용존무기질소, 용존무기인의 농도분포는 6개월 동안 증가한 농도분포가 차츰 감소하는 경향을 보였으며, 3년에서 10년 사이에서는 일정한 농도분포를 보였다. 화학적 산소요구량, 용존무기질소 및 용존무기인의 농도는 11~67%, 10~67% 및 0.57%의 범위로 증가하였다. 10년 동안의 수치 실험 결과 화학적산소요구량과 용존무기질소의 변화 폭이 크게 나타났으며 이는 하수처리장의 방류수 중 이 두 오염부하량이 많은 양을 차지하고 있기 때문이다. 아산만 연안해역에서 화학적산소요구량, 총질소, 총인의 농도는 해역수질환경기준 II등급으로 조사되었으나, 하수처리장의 방류수가 배출될 경우 사업지구 인근의 아산만 방조제 부근에서는 해역수질환경기준 III등급으로 나타났다.

To find proper water quality management strategy for oxygen consumption organic matters in Jinhae bay, the physical process and net supply/decomposition in terms of COD was estimated by three-dimensional eco-hydrodynamic modeling. The estimation results of physical process in terms of COD showed that transportation of COD was dominant in loading area from land to sea, while accumulation of COD was dominant in middle～bottom level. In case of surface level, the net supply rate of COD was 0～60 mg/m2/day. The net decomposition rate of COD was 0～-0.05 mg/m2/day(-5～-10 m, in depth) to 2 level, and -0.05～-0.20 mg/m2/day(10 m ～) to bottom level. These results indicate that the biological decomposition and physical accumulation of COD are occurred for the most part of Jinhae Bay bottom. The variation of net supply or net decomposition rate of COD as reducing land based input loading is also remarkable. Therefore, it is important to consider both allochthonous and autochthonous oxygen demanding organic matters to improve the water quality of Jinhae Bay.

The eco-hydrodynamic model was used to estimate the environmental capacity in Gamak Bay. It is composed of the three-dimensional hydrodynamic model for the simulation of water flow and ecosystem model for the simulation of phytoplankton. As the results of three-dimensional hydrodynamic simulation, the computed tidal currents are toward the inner part of bay through Yeosu Harbor and the southern mouth of the bay during the flood tide, and being in the opposite direction during the ebb tide. The computed residual currents were dominated southward flow at Yeosu Harbor and sea flow at mouth of bay. The comparison between the simulated and observed tidal ellipses at three station showed fairly good agreement. The distributions of COD in the Gamak bay were simulated and reproduced by an ecosystem model. The simulated results of COD were fairly good coincided with the observed values within relative error of 1.93%, correlation coefficient(r) of 0.88. In order to estimate the environmental capacity in Gamak bay, the simulations were performed by controlling quantitatively the pollution loads with an ecosystem model. In case the pollution loads including streams become 10 times as high as the present loads, the results showed the concentration of COD to be 1.33～4.74㎎/ℓ(mean 2.28㎎/ℓ), which is the third class criterion of Korean standards for marine water quality. In case the pollution loads including streams become 30 times as high as the present loads, the results showed the concentration of COD to be 1.38～7.87㎎/ℓ(mean 2.97㎎/ℓ), which is the third class criterion of Korean standards for marine water quality. In case the pollution loads including streams become 50 times as high as the present loads, the results showed the concentration of COD to be 1.44～9.80㎎/ℓ(mean 3.56㎎/ℓ), which is the third class criterion of Korean standards for marine water quality.

The three-dimensional eco-hydrodynamic model was applied to estimate the physical process in terms of nutrients and net uptake(or regeneration) rate of nutrients in Kamak Bay for scenario analysis to find proper management plan. The estimation results of the physical process in terms of nutrients showed that transportation of nutrients is dominant in surface level while accumulation of nutrients is dominant in bottom level. In the case of dissolved inorganic nitrogen, the results showed that the net uptake rate was 0～60 mg/m2/day in surface level(0～3m), and the net regeneration rate was 0.0～10.0 mg/m2/day in middle level(3～6m) and above 10 mg/m2/day in bottom level(6m～below). In the case of dissolved inorganic phosphorus, the net uptake rate was 0.0～3.0 mg/m2/day in surface level, and the net regeneration rate was 0.5～1.5 mg/m2/day in middle level and 1.0～3.0 mg/m2/day in bottom level. These results indicates that net uptake and transport of nutrients are occurred predominantly at the surface level and the net generation and accumulation are dominant at bottom level. Therefore, it is important to consider the re-supplement of nutrients due to regeneration of bottom water.

From the environmental aspects, primary productivity of phytoplankton plays the most important role in enhancement of marine culture oyster production. This study may be divided into two branches; one is estimation of maximum oyster meat production per unit facility(Carrying Capacity) under the present environmental conditions in Kamak Bay, the other is improvement of carrying capacity from increase of primary productivity by changing the environmental conditions that cause not to form an unfavorable environment such as the formation of oxygen deficient water mass using the eco-hydrodynamic model. By simulation of three-dimensional hydrodynamic model and ecosystem model, the comparison between observed and computed data showed good agreement. The results of sensitivity analysis showed that phytoplankton maximum growth rate was the most important parameter for phytoplankton and dissolved oxygen. The estimation of mean primary productivity of Wonpo, Kamak, Pyongsa, and Kunnae culture grounds in Kamak Bay during culturing period were 3.73gC/㎡/d, 2.12gC/㎡/d, 1.98gC/㎡/d, and 1.26gC/㎡/d, respectively. Under condition not to form the oxygen deficient water mass, four times increasing of pollutants loading as much as the present loading from river increased mean primary productivity of whole culture grounds to 4.02gC/㎡/d. Sediment N, P fluxes that allowed for 35% increasing from the present conditions increased mean primary productivity of whole culture grounds to 3.65gC/㎡/d. Finally, ten times increasing of boundary loadings from the present conditions increased mean primary productivity of whole culture grounds to 3.95gC/㎡/d. The maximum oyster meat production per year and that of unit facility in actual oyster culture grounds under the present conditions were 6,929ton and 0.93ton, respectively. This 0.93ton/unit facility is considered to be the carrying capacity in study area, and if the primary productivity is increased by changing the environmental conditions, oyster production can be increased.