Flood Prevention in Buenos Aires

October 9, 2013


Drainage tunnels construction in Buenos Aires

Gobierno de la Ciudad Autonoma de Buenos Aires

Buenos Aires has successfully carried out very complex public works unprecedent- ed in the country. This project consisted of two drainage tunnels, 9.8 kilometers long and 4.6 kilometers long, and 6 meters inner diameter. The project is directly benefitting over 300,000 people by reducing the intensity and frequency of flood- ing in the Maldonado Basin. The city Government is also equipped with a hydraulic plan for an integrated approach to flood prevention.


Flooding is a regular occurrence in Buenos Aires, reducing the quality of life, causing damage to property, and posing public health risks. Due to the combined effects of modified precipitation patterns, hydrological consequences of urbaniza- tion, and the volume of solid waste in the streets, the city’s drainage capacity has not kept up with its growth.

The resulting costs are especially severe as Buenos Aires is a significant engine for growth in the country. Among the several drainage basins in the city, flood recurrence has historically been especially problematic in the area around the former Maldonado Creek, which covers a central area of the city and is home to one third of the city’s population. In 2004, the Maldonado basin overflowed almost annually, clogging the city’s drainage system and causing flooding at significant cost both to its inhabitants and to commuters.


The Urban Flood Prevention and Drainage Project increased the city’s resilience to flooding through an integrated approach combining structural and non-structural measures. The project financed the construction of two critical drainage tunnels to improve the functioning of the Maldonado Basin drainage system.

The quality of the Bank’s technical support, the appointment of an independent panel of experts, and the contracting of a technical supervisor contributed greatly to the technical quality of these complex works. The project provided the city Government with a toolkit of vulnerability and risk analysis mechanisms to enable the design of an integrated flood management program for the wider city.


The successful implementation of this integrated approach provides an example of a good practice for other large infrastructure projects. Key results included:

  • Construction of two drainage tunnels, 9.8km and 4.6 km in length and 6 meters inner diam- eter, directly benefitting more than 300,000 people by reducing the intensity and frequency of flooding in the Maldonado Basin.
  • Improvement of the drainage capacity of the Maldonado Basin and reduction in material losses of inhabitants, compared to previous years and other basins.
  • Development of a hydraulic plan to implement an integrated approach to flood prevention within the city, indirectly benefitting 1.5 million people.
  • Equipping the city Government with capacity and tools for planning and identifying future investments and non-structural interventions.
  • Development of technical capacity to plan, design, and mathematically simulate the city’s drainage system.
  • A strongly engaged implementing agency in planning the operational phase of the works and identifying opportunities for replication in other basins.


The city of Buenos Aires contributed US$59 million, and the World Bank (IBRD) contributed US$130 million. 


The Project Implementation Unit was the Unidad de Proyecto Especial para el Arroyo Maldonado (UPEAM), housed within the Ministry of Urban Development in the City of Buenos Aires. 


The Project significantly improved the city’s ability to plan and implement investments of this scale and complexity, giving the Government the track record and vision to undertake the necessary resource mobilization for future works. Armed with the planning tools developed by the project’s non-structural investments, the Government has developed investment plans for the remainder of the basins in the city and is actively looking for funds. Buenos Aires is well-equipped to carry out the operation and maintenance of the project’s completed investments.


During the intense rainfall events in March, November and December 2012 (of which the December 2012 rains were equivalent to a 50 to 100-year event, with rainfall of 177mm in some areas), repeated press coverage and eyewitness testimonies from Buenos Aires inhabitants clearly indicate that while flooding was significant in other parts of the city, flooding in the project area was not significant and only found in some areas.

300,000 direct beneficiares
of the construction of two drainage tunnels, 9.8km and 4.6 km in length and 6 meters inner diameter in the Maldonado Basin