Devastating Floods Linked to Dam Bursts in Northeast Brazil

Lilian Alves and Brent Millikan

This is a guest blog by Amazon Program Intern Lilian Alves and Amazon Program Director Brent Millikan.

Dam burst on  Mundaú River, Rio Largo town, in the state of Alagoas
Dam burst on Mundaú River, Rio Largo town, in the state of Alagoas
Leo Caldas/Revista Veja
The Northeast of Brazil is well-known for its periodic episodes of severe drought that cause particular hardship for those already suffering from extreme poverty, especially in the region's backlands (sertão). Last month, however, the Northeast was hit by devastating floods, where over fifty people were killed and an estimated 150,000 were left homeless. The center of the tragedy has been the Mundaú and Paraíba river basins in the states of Alagoas and Pernambuco, where sudden massive flooding, likened by local observers to a tsunami, devastated towns, farms, bridges and even factories. In the town of Branquinha (Alagoas), an estimated 80% of residential housing was destroyed.

In additional to intense storms and abnormally high rainfall levels, the unprecedented flooding (despite initial denials by local politicians) has been directly linked to a series of dam bursts along the two rivers and their tributaries. The dam bursts reflect a lack of adequate safeguards in the construction and maintenance of both public and private dams, the latter typically for large sugarcane plantations. In the Northeast region, it is estimated that there are at least 100,000 small and medium dams, both old and new, most of which were built with little or no regard for environmental impacts and dam safety.

Devastating floods in the Northeast are also linked to the clearing of riparian woodlands and native vegetation on steep slopes, mainly for sugarcane monocultures, resulting in losses of water retention capacity, soil erosion and sedimentation of river channels. Another serious problem is the lack of adequate urban planning in towns and cities along floodplains that are occupied by rivers during periods of unusually intense rainfall. Such factors, combined with frequent extreme rainfall events associated with climate change, mean that the probability of dam failures is much higher, especially where older dams predominate.

The latest dam bursts in the Northeast highlight a recurrent problem in Brazil. In the last five years, at least six similar episodes were reported in different parts of the country, from the state of Pará in the North to Minas Gerais and Rio de Janeiro in the Southeast.  Last year, the bursting of the Algodões I dam in Piauí was reported in Glenn Switkes' blog, citing a recent study warning that more than 200 Brazilian dams were in serious risk of failing.

According to Renata Andrade, a specialist in environmental risk and river basin management at the Catholic University of Brasilia, "Populations living downstream from dams are increasingly vulnerable to flooding, due to a lack of dam safeguards and emergency preparedness programs. In the case of the Mundau river, there was no alert system in place to inform local populations of the imminent risks of the dam bursts and the subsequent flooding."

Evidence abounds of the misuse of government funds for flood prevention and emergency response in the Northeast. According to the watchdog NGO Contas Abertas, the Ministry of National Integration invested only 14% of US$ 279 million in its latest annual budget for disaster prevention in the region. Over half of the funds were allocated to the state of Bahia, where the former ministry head Geddel Vieira is currently running an electoral campaign for governor. Alagoas, one of the states devastated by the flooding of the Mundau and Paraíba rivers, apparently received no funds whatsoever.

According to Professor Andrade, "We need to address this situation of faster and increasing runoff through both prevention and safeguards to avoid such disasters as the domino effect of dam bursting that happened along the Mundaú river. We also need to think about how we are currently developing our river basins under climate change scenarios, in a manner that increases threats to humans, properties and the environment as a whole. We urgently need to improve the safety of dams and rethink the current land use situation, before another disaster occurs."

Note: In April, a bill creating the National Dam Safety Program and Policy (PLC 168/09) was finally approved by the Brazilian Congress. The bill was proposed after the disaster caused by the failure of Algodões I dam in Piaui. The new law calls for the creation of a national commission of dam safety, a risk management system with safety inspections and procedures and an emergency plan for the dams, including rules of accountability in case of dam bursts. The level of implementation of the new law and its effectiveness remain to be seen.