# Study of the Dynamic Adaptive Calculation Method for River Water Environmental Capacity
## 3 Methodology
### Dynamic Adaptive Calculation Method for Water Environmental Capacity
#### 3.2.2 Calculation Model and Method
In this study, the comprehensive attenuation coefficients of rivers under different pollutants, time scales, and river sections were determined using the measured data inversion method, as follows:  
\[W_{i}=(Q_{i}+q_{i})C_{s}-Q_{i}C_{s}f(x_{i}-x_{i-1}) \tag{2}\]6  
where \(C_{1}\) and \(C_{2}\) are the mass concentration of pollutants, mg/L and \(\Delta x\) is the distance between water function areas, m.  
3. Interval expression for water environmental capacity  
River hydrology, water quality, hydraulic, and other natural conditions are constantly changing. If only the value of a single WEC calculated under fixed conditions is used for decision-making, when the calculation conditions change, the value cannot continue to provide a reference for follow-up work, and cannot meet the needs of river water environment management in dynamic and changing environments [45]. Therefore, the interval expression of WEC is proposed (Figure 5), and the interval is used to replace a fixed value, so that a larger range can be provided in decision-making to adapt to the changes in various conditions. When representing the calculation results of WEC, considering the combination of different calculation methods, different level years, different water volumes, and other changes, different scenario conditions are formed, and the range of WEC composition forms the result interval. For the calculation result boundary, the maximum and minimum values  
\[W_{i}=(Q_{i}+q_{i})C_{s}-Q_{i}C_{s}f(x_{i}-x_{i-1}) \tag{2}\]7 Interval working principal diagram for WEC calculation results based on combination and synthesis. of the calculation model results under various changes are first used as the upper and lower bounds of the initial interval [46]. Subsequently, the decision makers participate in adjusting this initial interval, considering the adaptability of the current river and combining their own experience, to dynamically adjust the boundaries. For the application of the calculation model, according to the different characteristics of the water function area, combined with the environmental changes and the richness of the data, a suitable model is selected. For the high functional area, the high standard WEC calculation model is used. For the low functional area, the low standard WEC calculation model is used to ensure that the calculated interval results are accurate. In addition, the calculation model should be adjusted in time according to the actual situation, and then the result interval should be recalculated. According to this process, the calculation model should be continuously revised to adapt to the dynamic changes in the environment. With the continuous application of the system, based on the calculation model component library, according to the change combined with the calculation time-scale intelligent push adaptive model combination, the adaptability of the results is continuously improved. The advantage of the interval expression of WEC is to provide a result interval, to resolve the risks caused by changes when guiding pollutant discharge, to increase its adaptability, and to dynamically adapt and improve the quality of decision-making services in the implementation process.