Number of structures of concern jumped 53% in 1 year; however, incidents and accidents also dropped sharply
A report released by ANA (National Water and Sanitation Agency) showed that Brazil had 187 dams in critical condition last year, 66 of which are in Minas Gerais. From 2020 to 2021, the number of structures in this situation grew by 53%. Here’s the intact of the report (33 MB).
Read the evolution chart of critical dams from 2016 to 2021:
According to the document, in all, 9,451 dams have DPA (Associated Potential Damage), with 68% of them having potential damage classified as high.
According to the PNSB (National Policy on Dam Safety), the DPA can be high, medium or low. The classification is donebased on the potential for loss of human life and economic impacts, storage volume, social and environmental impacts resulting from an eventual dam failure”, explains the report.
The CRI (Risk Category) considers technical characteristics, state of conservation and compliance with the bus safety plan. 8,286 structures had CRI classification in 2021, with 28% being at high risk. In addition, 22% of the buses were simultaneously experiencing high DPA and CRI.
The PNSB regulates structures considered to be of greater risk, such as those with a height of the massif (wall) equal to or greater than 15 meters, total reservoir capacity equal to or greater than 3 million cubic meters, or that have a reservoir for the accumulation of hazardous waste, for example.
In 2020 and 2021, 701 dams were added to the SNISB (National Information System on Dam Safety). Today, 22,654 structures are registered in the system, of which 5,474 are submitted to the PNSB; 4,313 are not subject to the policy; and another 12,867 (57%) do not have enough information to qualify.
According to the report, 12,167 dams (or 54%) have height information; 19,744 (or 87%) by volume; and 11,488 (or 51%), some type of authorization act (grant, concession, authorization, license, etc.), being, therefore, regularized.
The numbers indicate an improvement compared to 2020, when the system had 13,095 dams (60% of the total of 21,953 dams) without sufficient information. Read the evolution chart:
Companies are responsible for keeping the data up to date with the supervisory bodies, as well as for the security of the structures.
The dam safety policy was intensified in 2020 after the tragedies of Mariana (2015) and Brumadinho (2019), in Minas Gerais.
The report shows that the tightening of siege was reflected in a sharp drop in the number of accidents and incidents in these structures in 2021: 13 accidents and 37 incidents were reported in 16 states. Most of them reached the central region of the country, due to heavy summer rains.
The previous year registered a record of occurrences since the beginning of the historical series, in 2011: there were 44 accidents and 95 incidents. From 2020 to 2021, there was a 52% reduction in the number of accidents and a 55% reduction in incidents.
Read the evolution graph of the number of occurrences in dams:
INVESTMENTS
Investments in dam safety also broke records in 2021. The budget had about R$199 million, 34% of which came from the federal and 66% from the state.
The amount effectively paid in 2021 was also the highest in the historical series: around R$128 million (64% of the originally forecast).
According to ANA, the largest expenditures were made by the Union with the rehabilitation of dams (R$ 41 million) and with the recovery of reservoirs of the São Francisco River Integration Project with the Northeastern Hydrographic Basins (R$ 25 million).
The regulatory agency warns that, despite the growth in investment, the amounts are below what is necessary to ensure preventive maintenance and compliance with legal requirements for dam safety.
The safety report is produced annually by ANA with data sent by 33 dam inspection entities. The purpose of the document is to present an overview of the evolution of security measures and guidelines for the performance of inspectors and companies managing these structures.
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