## 2 Materials and Methods
### Environmental Capacity Assessment System (ECAS)
#### 2.2.2.1 Environmental Capacity Estimation
In order to obtain the change of the boundary water level with time, this model selected the actual monitoring data of the water level on the three endpoints of the boundary (Lanshan Port, Pingdao Island and Yanwei Port) as the basis data, and applied the model to interpolate the water levels of other points on the boundary line, to obtain the change data of the water level on the lines connecting Lanshan Port to Pingdao Island, and Pingdao Island to Yanwei Port. Due to the availability of data, the water level data of Lanshan Port and Yanwei Port were obtained from the \"Tide Data 2019\", and the water level of Pingdao Island was obtained from the tide conversion formula of the main port, Lianyungang, according to the water level data of Lianyungang in \"Tide Data 2019\". 2 Closed boundary condition:  
Water Quality Model  
1. Basic water quality model. The two-dimensional convection-diffusion transport model adopted in this model is as follows:  
\[\frac{\partial}{\partial t}(hc)+\frac{\partial}{\partial x}(uhc)+\frac{ \partial}{\partial x}(vhc)=\frac{\partial y}{\partial x}\bigg{(}h\cdot D_{x} \cdot\frac{\partial c}{\partial x}\bigg{)}+\frac{\partial y}{\partial x} \bigg{(}h\cdot D_{y}\cdot\frac{\partial c}{\partial y}\bigg{)} \tag{5}\]where:  
_h_: depth of the water (m);  
_c_: concentration of pollutant (any unit);  
\(x\), _y_: horizontal velocity component in the x and y directions (m/s);  
_Dx_, _Dy_: dispersion in the x and y directions (m\({}^{2}\)/s);  
_F_: linear attenuation coefficient (seconds \({}^{-1}\));  
_S:Qs (\(c_{s}\)-c);_  
_Qs_: source and sink;  
_Cs_: pollutant emission concentrations in sources and sinks. The flow velocity and other information (including \(u,v\) and \(h\)) at each time step are provided by the hydrodynamic module. 2. The boundary conditions. 1 Open boundary conditions:  
The open boundary condition refers to the concentration of pollutants in seawater exchanged with seawater outside the open boundary. When calculating the water exchange rate of the reclamation schemes, COD was used as the tracer pollutant, and the initial value of COD concentration inside Haizhou Bay was set as 1 mg/L, and outside Haizhou Bay as 0 mg/L. 2 Closed boundary condition:  
The closed boundary condition is the boundary condition between land and water. Zero flux boundary conditions were used for this boundary. 3. Related parameters. 1 Degradation coefficient: The coefficient is related to the nature of a particular pollutant and can be adjusted during model calibration. When calculating the water exchange rate of the reclamation scheme, COD was used as the tracer pollutant and the degradation coefficient was set as 0. 2 Dispersion coefficient: Dispersion coefficient is the rate coefficient that represents the dispersion of pollutants in the flowing water along the direction of water flow, and the unit is square meters per second. When calculating the water exchange rate of the reclamation schemes, the calculation rate of dispersion coefficient was set as 18.7 m\({}^{2}\)/s. The linear programming model is expressed as:  
\[\text{max}Z=Q^{T}X \tag{6}\]  
required to meet:  
\[ \begin{cases}AX+B\leq S\\ X_{i}\leq X\leq X_{l}\\ X\geq 0\end{cases}  \tag{7}\]  
\[A= \begin{bmatrix}a_{11}&\dots&a_{1n}\\ \dots&a_{ij}&\dots\\ a_{m1}&\dots&a_{nm}\end{bmatrix}