## 3 Data and Methods  
### Data Collection and Processing  
In 2019, Anhui Province released The Chaohu Lake Basin Water Pollution Management Regulations, which will be officially implemented in 2020. In response to this policy, we selected the water quality monitoring data of Chaohu Lake from 2019 to 2022 for predictive modeling to ensure that the model matches the current stage of water quality, while aiming to provide a modern tool for water quality prediction in Chaohu Lake and to provide assistance for subsequent studies. Daily water quality data have been collected from the Chaohu Lake basin between 2019-2022 were obtained from the water quality monitoring reports provided in the 2022 summary by the China Environmental Quality Monitoring Bureau, which includes ten variables relevant to WQI calculations [23]: water temperature (\"C), pH, COD\({}_{\text{Mn}}\), turbidity (TUR), dissolved oxygen (DO), total nitrogen (TN), ammonia nitrogen (NH\({}_{4}\)-N), nitrite (NO\({}_{2}\)-N), total phosphorus (TP), nitrate nitrogen (NO\({}_{3}\)-N). Sampling, preservation, storage, and analysis procedures followed national surface water monitoring guidelines. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Serial Number** & **Monitoring Section** & **Longitude/(*)** & **Latitude/(*)** \\ \hline
1 & New River Intake Area & 117.3183 & 31.5930 \\
2 & West Half-Lake Center & 117.3754 & 31.6444 \\
3 & Chaohu Damkou & 117.8221 & 31.5933 \\
4 & Chaohu shipyards & 117.7178 & 31.6237 \\
5 & East Half-Lake Center & 117.6193 & 31.5186 \\
6 & Zhong Miao & 117.4623 & 31.5778 \\
7 & Zhaoge River Intake Area & 117.5472 & 31.4338 \\
8 & Huang Lu & 117.6265 & 31.5979 \\
9 & Lakeside & 117.4317 & 31.6707 \\
10 & Pai River Intake Area & 117.3069 & 31.6644 \\
11 & South Inter River Intake Area & 117.4008 & 31.6733 \\
12 & Hangbu River Intake Area & 117.3397 & 31.7053 \\
13 & Baishi Tianhe Intake Area & 117.4592 & 31.4692 \\
14 & Hangbu River Intake Area & 117.4050 & 31.5419 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Longitude and latitude distribution of Chaohu water quality monitoring section. Figure 2: Distribution of water quality monitoring section points in Chaohu Lake. With reference to the water quality parameters that have been collected and a number of current related studies, the integrated water quality index method proposed by PESCE and [PERSON] [23] was chosen to calculate the WQI by nine parameters, and the formula for WQI is expressed as follows:  
\[I_{\text{WQI}}=\frac{\sum_{i=1}^{n}C_{i}P_{i}}{\sum_{i=1}^{n}P_{i}} \tag{1}\]  
In the above equation, \(i\) is the total number of parameters included in the study; \(\text{C}_{i}\) is the normalized value of parameter \(i\) (Table 2); \(\text{P}_{i}\) is the weight assigned to the water quality parameter according to its effect on primary health perception (Table 3), the maximum weight of the parameters known to affect water quality is 4 and the minimum is 1. The accuracy of these parameter values have been verified in several studies [24,25], and \(\text{I}_{\text{WQI}}\) which is calculated on this basis by the above equation, is the integrated water quality parameter WQI that we need afterward. As visible in Table 3, the calculated WQI ranges from 0 to 100, and the better value symbolizes the better water quality situation According to the WQI score, the water quality is divided into five different levels: I Excellent (90-100 points), II Good (71-90), III Medium (51-70), IV Average (26-50), and V Poor (0-25) [26]. Under the guidance of the above method, the water quality parameters collected from the selected monitoring segments in the Chaohu Lake basin were analyzed and processed to obtain the descriptive statistics of the WQI variables as shown in Table 4 and to calculate the WQI for the corresponding time periods. In addition, the calculated WQI shows that the overall water quality situation in the Chaohu Lake basin varies widely, with specific values ranging from good excellent (WQI = 85) to average quality (WQI = 46) varying.