## 4 Results
### Nutrient Export Estimation Using NDR Model
#### 4.8.4 Nutrient Export Estimation of Predicted LULC under Scenario III  
The estimated total and average nitrogen and phosphorus export according to the predicted LULC between 2020 and 2029 and mean annual rainfall under Scenario III (Economic crop zonation) are presented in Table 30.  
As a result, the highest total and average nitrogen export under Scenario III were about 229,756 kg and 257.76 kg/km\({}^{2}\), respectively, occurring in 2029, while the lowest total and average nitrogen export were about 200,387 kg and 224.81 kg/km\({}^{2}\), respectively, occurring in 2020. Likewise, the highest total and average phosphorus export were about 51,149 kg and 57.38 tons/km\({}^{2}\), respectively, occurring in 2029, while the lowest total and average phosphorus export were about 43,956 kg and 49.31 kg/km\({}^{2}\), respectively, occurring in 2020. These results indicate that the changes in LULC types and areas affect parameters in the biophysical table, which leads to different nitrogen and phosphorus export, as observed in Scenarios I and II. The best fit of the sixth-order polynomial equation between annual rainfall and nutrient export had R\({}^{2}\) values of 0.9530 for nitrogen export and 0.9469 for phosphorus export (Figure 13). Figure 12: Relationship between mean annual rainfall and average nutrient export under Scenario II: (**a**) nitrogen and (**b**) phosphorus. Furthermore, the contribution of the predicted LULC under Scenario III on nutrient export indicated that the highest total nutrient and phosphorus export occurred on paddy fields. In contrast, the lowest total nitrogen export occurred on water bodies, while the lowest total phosphorus export occurred on miscellaneous land. Meanwhile, the highest average nitrogen and phosphorus export occurred on field crops, as well as perennial trees and orchards. These findings suggest that the change in LULC types associated with the biophysical table parameters affects nitrogen and phosphorus export. In particular, the LULC data under this scenario influenced nutrient export, according to the LULC data of Scenario III simulated based on the annual rate of LULC change from transition area matrix between 2009 and 2019 for some LULC types and the economic crop zonation, particularly the increase in paddy field and field crop areas and the decrease in perennial tree and orchard areas, which represented dramatic change under this scenario, leading to changes in the load amounts and export of nutrients. Hence, significant LULC change was observed under this scenario. The average nutrient (N and P) export between 2020 and 2029 for the three scenarios was compared, as shown in Figure 14, which shows that the predicted LULC under Scenario II (Maximization of ecosystem service values) delivered the lowest annual nitrogen and phosphorus export, compared to Scenarios I and III, due to the allocation of area using LP to maximize the ecosystem service values by increasing wetland areas. Increases in wetland areas, such as wetland restoration and constructed riparian wetlands, can reduce nitrogen [63] and phosphorus [64] export into water bodies. Furthermore, based  
Figure 13: Relationship between mean annual rainfall and average nutrient export under Scenario III: (**a**) nitrogen and (**b**) phosphorus.