Taking into account the conservation of a regional water environment, the allocation of the water resoruces should be deisgned not to achieve the economic optimization in an industrial activity but to conserve the water environment. The industrial activity plan is to design, regarding the allocation of the water resoruces as a constraint. From the above standpoint, the allocation of water resporuces including the assessement of the load impact on a coastal sea is analzyed in this paper.
There is a strong correlation between the water quality in a river and a sewerage equipment. Hence, using the annual change of the sewerage equipmentas a parameter, it is shown that when and how much the water resoruces is to be allocated in each region. The BOD load and the flow in the river is shown as a function of the water resoruces distribution and the level of the sewerage equipment; state equations are constructed; constraints and an objective function are presented. The model is a control process and able to solve by the method of a maximum principle. It is shown that the aforementioned model can be applied efficiently in the actual river basin.