Numerical modeling to define remediation actions for water quality in streams

Numerical modeling can play a key role in establishing an adequate strategy to achieve specific goals regarding water quality in streams. This is illustrated through an application to a big water basin with both rural and urbanized zones, and with degraded water quality. One-dimensional unsteady hydrodynamic modeling, linked to a hydrological model, is used. It is shown that the identification of the main pollutant sources, the estimation of their associated loads, and the assessment of non-point contributions, constitute a fundamental step in the model buildup. Only the relevant mechanisms are included in the water quality model. A challenging statistical criterion is proposed in order to calibrate the model. This model constituted the backbone for the formulation of the integral strategy adopted to remediate the water quality of the river, including the reduction in biochemical oxygen demand loads from big industries and water treatment plants, and the location and design parameters of aeration stations.