# Study of the Dynamic Adaptive Calculation Method for River Water Environmental Capacity
## 3 Methodology
### Dynamic Adaptive Simulation System for Water Environmental Capacity  
The WEC under different conditions is not the same. River WEC is constantly changing, the change in flow size, the change in water environment, human influences, and so on will lead to the change in WEC. The traditional method of calculating WEC is to calculate the WEC value under static conditions by setting specific calculation conditions, determining the calculation period, fixed calculation parameters, etc. The calculation results are the WEC under specific conditions, which are mostly used for planning, but cannot be applied in practice. Therefore, in this paper, a dynamic adaptive calculation method of WEC is proposed which adapts to the change in hydrological conditions and social needs, and the realization of this method needs the support of information technology. Based on the database technology and the knowledge visualization integrated platform, the application of this method is realized, and the WEC dynamic adaptive computing system for the Shaanxi section of Wei River is designed and developed [47]. The design of the knowledge visualization integration platform conforms to the Technical Specification for Water Conservancy Information Processing Platform (SL538-2011), which is the standard in the water conservancy industry. The platform is based on service-oriented architecture (SOA) design, and uses theme, component, and knowledge graph visualization to build a business system. The system integrates various types of information, business application systems, and existing systems, finally providing Web services. On the platform, a multi-node big data service platform can be built based on a Hadoop or Spark framework. The typical cases completed by the platform include the comprehensive regulation of water resources security in Beijing-Tianjin-Hebei, the decision-making of hydropower dispatching in Shaanxi, and the comprehensive service of water resources in the Wei River. The main interface of the WEC dynamic adaptive computing system for the Shaanxi section of the Wei River, which is based on this platform, is shown in Figure 6. Each rectangular button or icon depicted in the diagram represents a business node and corresponds to a relevant component. By clicking on a node, you can view the relevant information associated with it. In the calculation process, to select calculation conditions by clicking on nodes, choosing the pollutant type (COD, NH\({}_{3}\)-N), calculation method (standard model, etc. ), design frequency (90%, 70%, 50%), time scale (yearly scale, wet, normal, and dry period, monthly scale), hydrological conditions, etc., you can select according to different needs. The calculation results will change with the change in calculation conditions. By clicking on the results of statistical nodes, users can view the calculation results in the form of tables or graphics. In addition, the river is generalized with the line segments, red dots,and blue dots shown in the figure. The line segments in the figure are the water functional areas, the red dots are the water quality and hydrological sections, and the blue dots are sewage outlets. The decision maker can obtain the WEC of each water function area under different calculation conditions by selecting the calculation conditions and clicking on the line segment representing the water function area. At the same time, users can click on the red dot representing the water quality and hydrology section to view the basic information of each water functional area, and click on the blue dot representing the sewage outlet to obtain the amount of sewage. Through this system, managers can manage rivers more scientifically and adaptively. Figure 7 shows the calculation results of the WEC in the Shaanxi section of the Wei River. The first table on the left-hand side of the figure shows the statistics on the discharge volume of each sewage outlet in the Xianyang industrial water area of the Wei River.