Uma metodologia para avaliar a vulnerabilidade de pequenos sistemas comunitários de água para consumo humano

Debiasi, Ronaldo; Benetti, Antônio Domingues

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Technical Note • RBRH 24 • 2019 • https://doi.org/10.1590/2318-0331.241920190010 copiar

Uma metodologia para avaliar a vulnerabilidade de pequenos sistemas comunitários de água para consumo humano

Autoria SCIMAGO INSTITUTIONS RANKINGS

RESUMO

Em muitos países, pequenos sistemas comunitários têm um importante papel como supridores de água para consumo humano para grande parte da população. Estes sistemas devem ser avaliados com respeito a suas capacidades em produzir e entregar água segura para consumo humano. Como existem milhares de pequenos sistemas a serem avaliados nas regiões, é necessário desenvolver procedimentos para selecionar uma amostra representativa, assim como a escolha de indicadores que deem informações sobre o estado dos sistemas. O objetivo deste estudo foi propor e aplicar uma metodologia para avaliar a vulnerabilidade de pequenos sistemas comunitários de água para consumo humano. A metodologia inclui indicadores de vulnerabilidade, classificação e índice. Como estudo de caso, a metodologia foi aplicada para determinar a vulnerabilidade de pequenos sistemas no estado do Rio Grande do Sul, Brasil. As informações coletadas com a aplicação da metodologia proposta indicaram que 67% dos sistemas considerados foram classificados como tendo vulnerabilidades altas e médias, desta forma com risco de estarem distribuindo água que não é segura para consumo humano.

Palavras-chave:
Avaliação de vulnerabilidade; Sistemas comunitários de abastecimento de água; Pequenos sistemas de abastecimento de água; Indicadores de vulnerabilidade e índices; Vulnerabilidade de sistemas de abastecimento de água

Dimension	Indicator	Definition
Water resources	Water resources availability	Occurrence of events such as droughts and floods that affects the continuity of the water supply.
	Water source	Type of water source used for supply.
	Level of treatment	Adequacy of the treatment technology to the source water quality.
	Drinking water quality	Water quality characteristics.
	Operations & maintenance	O&M conditions of the water supply system infrastructure.
	Water distribution network	Occurrence of problems in the water distribution network.
Economic	Economic sustainability	Economic sustainability for the system O&M and investments.
Human Resources	Technical capacity	Technical capacity of the system personnel.
Institutional	External support	Support from health agencies, local government, and/or non-governmental organizations.
Institutional	Surveillance and control: water quality monitoring	Surveillance and control monitoring of the drinking water quality in compliance with health regulations.

Indicator	Value	Vulnerability	Reasoning
Water resources availability	0.00	Annual occurrence of events	An event occurs when the availability of water is limited due to droughts or floods.
	0.25	Three events in the last five years
	0.50	Two events in the last five years
	0.75	One event in the last five years
	1.00	None in the last five years
Water source	0.00	Unprotected surface or groundwater	Groundwater is generally less vulnerable to contamination than surface water.
	0.25	Partially protected surface water or phreatic well
	0.50	Partially protected artesian well
	0.75	Protected surface water or phreatic well
	1.00	Protected artesian well
Level of treatment	0.00	None	The level of treatment technology must be adequate to the raw water quality. It must also comply with established regulations (for instance, disinfection).
	0.25	Inadequate treatment technology
	0.50	Partially adequate treatment technology
	0.75	Proper treatment technology
	1.00	Above the required treatment technology
Drinking water quality	0.00	Occurrence of Escherichia coli	Generally, the greatest health concern to water quality comes from contamination by pathogens. Taste and odor can cause rejection of treated water.
	0.25	Occurrence of total coliforms but not Escherichia coli
	0.50	Absence of coliforms and Escherichia coli but with concentration of residual disinfectant below regulated levels.
	0.75	Absence of coliforms and Escherichia coli, residual disinfectant concentration above the regulated level. Occurrence of acceptability parameters (taste, odor and color)
	1.00	Full compliance to water quality regulations
Operations & maintenance	0.00	Without O & M	One of the main difficulties associated with providing safe water is the operation and maintenance of the water supply systems.
	0.25	Irregular frequency O & M
	0.50	Regular but insufficient O & M
	0.75	Adequate O & M
	1.00	Optimal O & M
Water distribution network	0.00	Daily interruption in the distribution of drinking water	The occurrence of problems in the water distribution network, such as leaks, breaks, corrosion, low pressure, and material of low quality can cause the interruption of the service, with potential external contamination.
	0.25	Once a week interruption.
	0.50	Once a month interruption
	0.75	Once every six months interruption
	1.00	Once a year interruption.
Economic sustainability	0.00	Inexistent resources for investments and O&M	The collection of fees ensures a secure source of revenue to cover operating, maintenance and investment costs.
	0.25	Insufficient resources for investments and O&M
	0.50	Sufficient resources for O&M but insufficient for investments
	0.75	Enough resources for O&M and minor investments
	1.00	Sufficient resources for O&M and investments in the system upgrade
Technical capacity	0.00	Operator without proficiency	The operation of a water supply system is complex, encompassing pumps, chemicals, pipes and associated appurtenances, requiring technical training.
	0.25	Operator partially proficient without regular training
	0.50	Operator proficient but without regular training
	0.75	Operator proficient having regular training
	1.00	Operator fully proficient and with regular training
External support	0.00	Unavailable external support and assistance	The existence of external support and assistance contributes to the quality of the water supply systems.
	0.25	Insufficient external support and assistance
	0.50	Regular external support and assistance
	0.75	Sufficient external support and assistance
	1.00	Optimal external support and full assistance
Surveillance and control: water quality monitoring	0.00	Inexistent	Monitoring is important to secure drinking water quality, for early detection of problems and to comply with health regulations.
	0.25	Insufficient
	0.50	Regular
	0.75	Partial compliance
	1.00	Full compliance

Stratum (Geographical Region)	Population served by small water supplies	Number of systems	Number of clusters	Number of selected clusters	Number of selected systems
Central West, Southeast and Southwest¹ 1 Geographical regions Central West, Southeast and Southwest were merged in one stratum to produce a sample of at least two clusters.	51,240	705	43	2	6
Center East	96,789	524	35	3	9
Metropolitan	99,832	565	51	3	9
Northeast	88,385	882	50	3	9
Northwest	316,656	3,600	164	9	27
Total	652,861	6,276	343	20	60

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[1] E-mails: ronaldo@agergs.gov.br (RD), benetti@iph.ufrgs.br (ADB)