## 4 Results
### Nutrient Export Estimation Using NDR Model
#### 4.8.3 Nutrient Export Estimation of Predicted LULC under Scenario II  
The estimated total and average nitrogen and phosphorus export of predicted LULC between 2020 and 2029 and mean annual rainfall under Scenario II (Maximization of ecosystem service values) is presented in Table 29.  
As a result, the highest total and average nitrogen export occurred in 2020, with values of about 196,965 kg and 220.97 kg/km\({}^{2}\), respectively, while the lowest total and average nitrogen export occurred in 2022, with values of about 195,426 kg and 219.25 kg/km\({}^{2}\), respectively. Likewise, the highest total and average phosphorus export were in 2029, with values of about 43,798 kg and 49.14 kg/km\({}^{2}\), respectively, while the lowest total and average phosphorus export occurred in 2022, with values of about 42,961 kg and 48.20 kg/km\({}^{2}\), respectively. These results indicate that the changes in LULC types and areas affect parameters in the biophysical table, leading to variations in nitrogen and phosphorus export.  
Figure 11: Relationship between mean annual rainfall and average nutrient export under Scenario I: (**a**) nitrogen and (**b**) phosphorus.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Year**} & \multicolumn{2}{c}{**Area**} & \multicolumn{2}{c}{**Nitrogen Export**} & \multicolumn{2}{c}{**Phosphorus Export**} & \multicolumn{2}{c}{**Mean Annual Rainfall**} \\ \cline{2-6}  & **km\({}^{2}\)** & **Total (kg)** & **Average (kg/km\({}^{2}\))** & **Total (kg)** & **Average (kg/km\({}^{2}\))** & **(mm)** \\ \hline
2020 & 891.35 & 196,964.74 & 220.97 & 43,117.85 & 48.37 & 1523.53 \\
2021 & 891.35 & 195,883.51 & 219.76 & 42,988.62 & 48.23 & 1508.50 \\
2022 & 891.35 & 195,426.12 & 219.25 & 42,961.10 & 48.20 & 1465.20 \\
2023 & 891.35 & 195,754.01 & 219.62 & 43,137.70 & 48.40 & 1517.76 \\
2024 & 891.35 & 195,641.77 & 219.49 & 43,160.14 & 48.42 & 1537.45 \\
2025 & 891.35 & 195,988.64 & 219.88 & 43,334.48 & 48.62 & 1544.38 \\
2026 & 891.35 & 195,915.15 & 219.80 & 43,415.07 & 48.71 & 1486.75 \\
2027 & 891.35 & 196,276.87 & 220.20 & 43,540.77 & 48.85 & 1472.48 \\
2028 & 891.35 & 196,689.44 & 220.66 & 43,714.70 & 49.04 & 1539.43 \\
2029 & 891.35 & 196,815.34 & 220.81 & 43,797.81 & 49.14 & 1498.28 \\ \hline \hline \end{tabular}
\end{table}
Table 29: Estimation of nitrogen and phosphorus export between 2020 and 2029 under Scenario II.  
As with Scenario I, the annual rainfall, as a runoff proxy, was not a sensitive factor for estimating nutrients. The best fit of the sixth-order polynomial equation between annual rainfall and nutrient export had R\({}^{2}\) values of 0.4920 for nitrogen export and 0.8834 for phosphorus export (Figure 12).  
Moreover, the contribution of the predicted LULC under Scenario II on nutrient export demonstrated that the highest total nitrogen and phosphorus export occurred on the paddy fields. In contrast, the lowest nitrogen export occurred on water bodies, while the lowest phosphorus export occurred on miscellaneous land; however, the highest average nitrogen export appeared on paddy fields and field crops, while the highest average phosphorus export occurred on perennial trees and orchards.  
Additionally, these findings suggest that the change in LULC types associated with the biophysical table parameters affects nitrogen and phosphorus export. Notably, the LULC data under this scenario influenced nutrient export due to the LULC data of Scenario II, simulated based on the annual rate of LULC change from transition area matrix between 2009 and 2019 for some LULC types and the LP to maximize ecosystem service values, by reducing the area of rangeland and miscellaneous land and increasing the area of wetland. Therefore, significant LULC change was observed under this scenario, due to the area change, load amounts, and export of nutrients.