## 4 Analysis of Water Environment Quality by Urban Function Division  
AMOS was used for path analysis. Data obtained from the data search and field research were first imported into SPSS and saved in \"sav\" format. The standardization function coefficient in the SEM was used to reflect the relationship between latent variables and measured variables, and latent variables and the correlation of the water environment quality. To verify the fitting degree and the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Land Use Type** & **COD (kg/cm\_km2)** & **TN (kg/cm\_km2)** & **TP (kg/cm\_km2)** \\ \hline Residential area & 51 & 5.8 & 1.5 \\ Business district & 207 & 13.1 & 3.3 \\ Industrial area & 78 & 12.2 & 3.1 \\ Other land & 9 & 2.7 & 0.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Pollutant concentration parameters. Figure 7: Relationship of pollutant emission distribution, pollutant emission level, and functional division and (**a**) TN, (**b**) TP, and (**c**) COD concentration in each division. effective degree of the SEM, we selected several commonly used indexes (absolute index, relative index, and contracted index). As shown in Table 6, all indexes were within the range of the fitting standard, so the fitting degree of this model is considered good and met the study requirements. The direct effect coefficient of external water environment on water environment quality was 0.78, indicating that an increase in COD, total nitrogen, and total phosphorus emissions will lead to the deterioration of water environment quality and more serious pollution. The effect coefficient of the water environment on water environment quality was \(-0.56\), indicating that an increase in pollutant environmental capacity improves water environment quality and positively affects water environment quality. By comparing the effect coefficient, we found that the external influences of the water environment were greater than the water environment itself, indicating that the effects of pollution caused by human production and living activities on water quality are stronger than the sustainability of the water body, so water quality is affected and polluted. Figure 8 depicts the standard action coefficient. The upstream water quality and purification capacity indirectly affected the water environment quality by affecting the water environment. An increase in pollutant concentration in the upstream water had a negative impact on the water environment and indirectly led to the deterioration of water environment quality. The purification capacity of water quality positively impacted the water environment. The stronger the purification capacity of water, the better the water environment; the higher the environmental capacity of pollutants, the better the water environment quality. Point source and non-point source load, by externally influencing the water environment, indirectly impact water environment quality. Increases in point source and non-point source loads negatively impacted water environment quality. Water environment quality, including the role of the point source pollution coefficient, has a much larger influence than the effect coefficient of non-point source pollution, illustrating that the point load is an important factor affecting the water environment quality. Therefore, controlling point source pollution and pollutant discharge is important for improving water environment quality. As shown in Table 7, the contribution of each measurement variable to water environment quality was calculated using the contribution rate calculation formula. The contribution rates of upstream water quality, water quality purification capacity, point source load, and non-point source load to water environment quality were 20.85%, 18.37%, 40.54%, and 20.24%, respectively. This indicates that point source load was the most important factor affecting the water environment quality and the discharge and concentration of various pollutants are still the main reasons for the deterioration of water quality.