Assessment of the impact of diffuse pollution on river water quality with limited data: application to the Cau River watershed
The main objective of this work is to evaluate the influence of different pollution sources on the water quality of the Cau River watershed in Vietnam. The tool used for this evaluation is GIBSI (Gestion Intégrée par Bassin versant à l’aide d’un Système Informatisé). For this assessment, the sub-models PO, to simulate the transport of nitrogen and phosphorus, and Qual-GIBSI, to simulate river water quality, will be used. In order to apply these models, an original method of regionalised calibration, taking into account the characteristics of different zones in the watershed, is developed. This approach makes it possible to take account the characteristics of the different zones of the catchment area in order to reproduce the observed data as well as possible. Then, from scenarios, the effect of different pollution sources is compared. In particular, the impact on water quality on Cau River watershed of diffuse pollution from agricultural sources and rural domestic origin is assessed. The results show that diffuse pollution has a greater impact on the degradation of water quality on this watershed than other pollution sources.