Studying Water Quality on the Coast of the City of Buenos Aires

Overview

The coastal waters of Buenos Aires are influenced by discharges from urban rivers, creeks, and stormwater conduits throughout the metropolitan area. Many of these inputs carry contaminants that accumulate near the shoreline, affecting water quality and limiting recreational use. At the same time, planned infrastructure works aimed at intercepting and treating polluted flows provide an opportunity for environmental improvement.

To support these efforts, HCS developed a numerical modeling framework for the Río de la Plata focused on the dynamics of coastal circulation and contaminant transport. The system integrated hydrodynamics with a representation of pollutant dispersion to allow a clearer understanding of how different sources affect shoreline conditions.

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The Challenge

Pollution along the Buenos Aires coastline results from a combination of:

• Major tributaries discharging into the estuary
• Local creeks and drainage channels
• Numerous stormwater and urban runoff points

Because coastal currents in the Río de la Plata are often aligned with the shoreline, contaminants tend to remain nearshore and can be transported over long distances depending on tide and wind conditions.

City planners required a tool capable of:

• Identifying the relative influence of different pollution sources
• Understanding how contaminants spread along the coast under varying conditions
• Evaluating the potential benefits of planned remediation and collection works
• Supporting long-term water-quality management strategies

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Our Contribution

HCS updated and expanded a hydrodynamic and contaminant-transport model for the estuary, incorporating:

1. Hydrodynamic Simulation

A two-dimensional model representing the main physical drivers of coastal circulation, including river inflows, tides, and meteorological forcing. The model reproduced the large-scale patterns of flow along the shoreline, which control how contaminants move and accumulate.

2. Contaminant Transport Module

A complementary module was used to simulate how representative pollutants disperse from different sources, allowing the evaluation of relative impacts and spatial distribution patterns.

3. Integration of Monitoring Data

Observed water-quality information from multiple coastal stations was used to ensure that model behavior was consistent with measured conditions and to interpret the results within the context of actual shoreline variability.

4. Scenario Analysis

The modeling framework was applied to compare different remediation and management scenarios, including improved collection of polluted flows and other proposed interventions. These simulations helped identify the strategies that produce the most meaningful improvements in coastal water quality.

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Figure 1: Model mesh, general view

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Figure 2: Model mesh, detail view

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Key Findings

While the detailed quantitative results are specific to the client, the modeling provided:

• A clearer understanding of how coastal hydrodynamics shape contaminant plumes
• Identification of areas where pollutants tend to accumulate or disperse
• Insight into the relative importance of different pollution sources
• A technical basis for evaluating the effectiveness of proposed remediation actions

The simulations highlighted the sensitivity of coastal water quality to the interaction between river discharge, tides, and local discharges, underscoring the need for integrated management at the metropolitan scale.

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Outcomes and Client Value

The modeling system delivered by HCS provided authorities with:

• A consolidated tool for interpreting coastal water-quality conditions
• Evidence-based support for prioritizing remediation actions
• Scenario analyses to assess the potential benefits of planned infrastructure
• A scientific foundation for long-term water-quality management policies

This project demonstrates HCS’s ability to develop modeling tools that combine hydrodynamics, contaminant transport, and scenario evaluation to support environmental decision-making for major urban coastal systems.