The role of precise management in mitigating non-point source nitrogen pollution of a reservoir region: Environmental profits and economic benefits

Non-point source pollution is a worldwide water environment pollution problem, which could be effectively solved with the concept and method of precision management. In this study, an integrated optimization decision system (IODS) was developed for supporting precise management of non-point source nitrogen pollution under multiple uncertainties. Several kinds of methods were innovatively coupled into the IODS, including material flow analysis (MFA), Gumbel copula model (GCM), path analysis (PA), and interval multi-objective chance constraint programming (IMOCCP). The IODS could (i) identify the main sources of non-point source pollution through the MFA; (ii) estimate the pollution status of different zones within the entire watershed using the GCM and PA; (iii) incorporate the pollution sources and pollution status to the IMOCCP as decision variables and development scenarios (i.e., S1 to S3), respectively. The settlement of the IMOCCP model could provide targeted optimal solutions to zones of different pollution status, with minimized non-point source nitrogen pollution and maximized economic benefit. Our research demonstrates great advantage of precise management in obtaining more environmental profits and economic benefits. Specifically, the precise management makes the system benefit increased by about [89.86%, 96.10%], [87.35%, 95.00%], and [28.23%, 60.40%] from S1 to S3, respectively. While the nitrogen loading decreased by about [23.40%, 81.84%], [66.51%, 145.72%], and [385.05%, 623.16%], correspondingly. This work may offer inspiration and guidance for the practice of precise management in mitigating the non-point source pollution.