1.2 Detalhes do contato das pessoas capacitadas e instituições envolvidas na avaliação e documentação da tecnologia

Nome do projeto que facilitou a documentação/avaliação da Tecnologia (se relevante)

Book project: where people and their land are safer - A Compendium of Good Practices in Disaster Risk Reduction (DRR) (where people and their land are safer)

Nome da(s) instituição(ões) que facilitou(ram) a documentação/ avaliação da Tecnologia (se relevante)

Terre des Hommes (Terre des Hommes) - Suíça

1.3 Condições em relação ao uso da informação documentada através de WOCAT

O/a compilador/a e a(s) pessoa(s) capacitada(s) aceitam as condições relativas ao uso de dados documentados através da WOCAT:

Sim

1.4 Declaração de sustentabilidade da tecnologia descrita

A tecnologia descrita aqui é problemática em relação a degradação da terra de forma que não pode ser declarada uma tecnologia de gestão sustentável de terra?

Não

2.1 Descrição curta da tecnologia

Definição da tecnologia:

The combination of pond sand filters (PSF) and raised pond embankments protect drinking water sources and increase the resilience to flood and tidal surge events in low-lying coastal areas.

2.2 Descrição detalhada da tecnologia

Descrição:

Coastal areas along the Bay of Bengal experience extreme seasonal variance in the presence of surface water including flooding, tidal surge, and drought. Many families living in these rural communities construct small ponds to ensure water availability for a variety of uses, such as washing, bathing, fish farming and animal watering as well as domestic use. Some families build larger ponds that are open to the use of all community members; whereby water is carried by women and children to households. Use of pond surface water may last up to several months during the year depending on the location, seasonal weather patterns, geologic conditions, capacity of the pond and user habits. Residents rely on ponds as a source of drinking water during the dry season when household rainwater harvesting techniques are no longer viable, making treatment essential.

Pond sand filters (PSF) is acentralised or semi-centralised water treatment technology often employed in many coastal areas where surface water is the only option due to saline aquifers and lack of resources for more robust, safely managed community water supply systems. The technology uses slow-sand filtration to remove turbidity (sediments) and pathogenic organisms whereby freshwater flows through layers of sand and gravel populated by a thin layer of microorganisms and treatment happens through physical and biological processes. Due to resource constraints, the number of PSF serving as water sources is usually limited. The technology considerably reduces the risk of infection with enteric pathogens. In conjunction with PSF, safe water transport (covered and cleaned containers) and household water treatment systems (chemical or additional filtration devices) are essential.
As stated in the Sustainable Sanitation and Water Management Toolbox (SSWM) slow sand filtration systems are characterised by a high reliability and rather low lifecycle costs. Moreover, neither construction nor operation and maintenance require more than basic skills. Hence, slow sand filtration is a promising filtration method for small to medium-sized, rural communities with a fairly good quality of the initial surface water source. As stated by the the World Health Organisation, slow sand filtration provides a simple but highly effective and considerably cheap tool that can contribute to a sustainable water management system.
Once a SSF facility is built, only clean sand is required for occasional replacement. The sand layers are put in gradually according to their grain sizes: rather coarse grains at the bottom and fine grains at the top. The sand-bed is usually covered with one meter of supernatant water (LOGSDON 2003). As the process of biological filtration requires a fair amount of time in order to improve effectiveness of water treatment, SSFs usually operate at slow flow rates between 0.1 – 0.3 m3/h per square metre of surface (WHO n.y.). The water thus remains in the space above the medium for several hours and larger particles are allowed to separate and settle. It then passes through the sand-bed where it goes through a number of purification processes (HUISMAN 1974).

Due to the risk of inland flooding and (seawater) tidal surges from offshore storms, communities build earthen embankments around the ponds to prevent contamination. Local authorities and community members must be involved in the design height of the embankment—which should be equivalent to the highest pre-recorded flood level. In the geo-referenced area (Patharghata) this is equivalent to the tidal surge of Cyclone Sidr (2007). Constructed roadways are often a good reference point. In southern Bangladesh , rural roadways are built to at a ten-year flood return period, so exceeding this height according to the means of the community and/or project is recommended.
Pond embankments are best raised with soil preferably of a clayey nature. The final covering layer must be rich in clay. Embankments should be planted with native grasses and flora that have strong root systems to stabilize slopes and prevent erosion during the rainy season and in cases of tidal surge due to storms. In Bangladesh, the native kolmi (Ipomoea) has proven effective. Community members have also planted crops on the embankments, such as banana trees, medicinal plants and even small garden trenches in the middle of the slope. Beyond structural support, the horticulture helps diversify nutrition and can provide a source of income for maintaining the pond sand filter.
Fences should be installed to prevent animals from entering ponds reserved for drinking water. Community members must guarantee that the ponds selected for PSF construction shall not be used for purposes such as: washing, bathing, fish farming (natural fish however can be allowed), direct cattle access washing and watering. Furthermore:
•Fertilizers and other chemicals shall never be allowed to go into the pond.
•The flow of any polluting materials in the vicinity of the pond shall always be directed away from the pond.
•Latrines, cowsheds, garbage dumps, graveyards, fuel outlets and similar polluting structures shall not be constructed within a distance of 30 meters from the pond.
•Duck or poultry rearing hanging sheds shall never be constructed over the pond.

2.3 Fotos da tecnologia

2.5 País/região/locais onde a tecnologia foi aplicada e que estão cobertos nesta avaliação

2.6 Data da implementação

Caso o ano exato seja desconhecido, indique a data aproximada:

• menos de 10 anos atrás (recentemente)

2.7 Introdução da tecnologia

Especifique como a tecnologia foi introduzida:

• Como parte do sistema tradicional (>50 anos)
• através de projetos/intervenções externas

3.1 Principal/principais finalidade(s) da tecnologia

• Reduzir riscos de desastre
• Adaptar a mudanças climáticas/extremos e seus impactos

3.2 Tipo(s) atualizado(s) de uso da terra onde a tecnologia foi aplicada

Uso do solo misturado dentro da mesma unidade de terra:

Sim

Especificar o uso misto da terra (culturas/ pastoreio/ árvores):

• Agrofloresta

3.3 O uso do solo mudou devido à implementação da Tecnologia?

O uso do solo mudou devido à implementação da Tecnologia?

• Não (Continuar com a pergunta 3.4)

3.4 Abastecimento de água

Abastecimento de água para a terra na qual a tecnologia é aplicada:

• Precipitação natural

3.5 Grupo de GST ao qual pertence a tecnologia

• Gestão de água de superfície (nascente, rio, lagos, mar)

3.6 Medidas de GST contendo a tecnologia

3.7 Principais tipos de degradação da terra abordados pela tecnologia

Comentários:

Preventing salt water intrusion, the surface water quality and quantity is protected. Turfing and planting the embankment prevents erosion.

3.8 Redução, prevenção ou recuperação da degradação do solo

Especifique o objetivo da tecnologia em relação a degradação da terra:

• Não aplicável

4.1 Desenho técnico da tecnologia

4.2 Informação geral em relação ao cálculo de entradas e custos

Especifique como custos e entradas foram calculados:

• Por unidade de tecnologia

Especifique a moeda utilizada para os cálculos de custo:

• USD

4.3 Atividades de implantação

	Atividade	Periodicidade (estação do ano)
1.	Community consultation for Committee Formation	Before onset of rain
2.	Create PSF Users' Committee, agre on user contributions	Before onset of rain
3.	Committee / pond selection approved by local Government	Before onset of rain
4.	Technical orientation to PSF Committee, input on designs	Before onset of rain
5.	Excavation of Pond	Before onset of rain
6.	Embankment Construction	Before onset of rain
7.	PSF Construction
8.	Fencing
9.	Turfing and hortiuclutre on the embankment	Before onset of rain
10.	PSF Training on Media Selection and maintenance	Regular intervals throughout the year (every 1-2 months)
11.	Pond embankment maintenance	Before onset of rain

Comentários:

In general, the community approach begins with several consultation meetings in the community (inclusive: gender balanced and representative of the diversity makeup of the community) and with municipal authorities. An Outcome Mapping process is initiated to observe signs that a village is prepared and mobilized to receive support for PSF and pond embankment construction. Families must be willing to participate and contribute in the construction and take complete responsibility for operation and routine maintenance.
During the initial phase, a PSF Users’ Committee is formed and approved by the municipal government. Its members make time to participate in trainings on the design, use, maintenance and community organization for managing a PSF. Importantly, the PSF User’s committee must seek public commitments toward the construction costs in cash and/or in kind (labor, construction materials, embankments plants, etc). In Bangladesh this was 10% and usually in kind. Roles and responsibilities of the PSF Users’ Committee:
1)Be responsible for regular operation, maintenance and cleanliness of the pond sand filter;
2)Ensure that the maintenance points for pond water quality is respected per the manual;
3)Advocate for local authorities to conduct regular water quality testing; and to promote household water treatment systems
4)Establish a system of collecting money from users for the regular maintenance;
5)Organize Committee meetings before the start of each season and whenever needed. Similarly if required organize a wider meeting with users in connection with resolving any O&M issues.
6)Care for the tools and other materials that may be purchased for the pond sand filter.
Selection of ponds for PSF construction should be participative with criteria agreed and communicated with the community members and local authorities. The following criteria are suggested based on Terre des hommes’ experience in Bangladesh:
•Ponds that are large enough to retain water throughout the dry season.
•The salinity of the pond water must not exceed 600 ppm at any time of the year.
•While the location of the PSF should be close to a family to ensure its security, it must be as centrally located as possible for ease of access
•Freely accessible to the public; ideally donated for public use.
•Ponds located on higher ground and thus more resistant to flooding / sea water intrusion.
•Space available for raising the embankments around the ponds
•Ponds most accessible to a largest segment of the population during disaster.
•Each PSF should have an effective drainage space and system.

4.4 Custos e entradas necessárias para a implantação

	Especifique a entrada	Unidade	Quantidade	Custos por unidade	Custos totais por entrada	% dos custos arcados pelos usuários da terra
Mão-de-obra	Pond Excavation and Embankment Raising	Person-days	180,0	5,0	900,0	10,0
Mão-de-obra	Pond Fencing Works	Person-days	20,0	5,0	100,0
Mão-de-obra	Masonry	Person-days	36,0	6,25	225,0
Equipamento	Repairing tools	Set	1,0	15,0	15,0
Equipamento	Tubewell/handpump	Pieces	1,0	35,0	35,0	10,0
Equipamento	Sanitary Fittings	Set	1,0	100,0	100,0
Fertilizantes e biocidas	Bleaching powder for disinfection	kg	2,0	1,0	2,0	10,0
Fertilizantes e biocidas	Lime for cleaning	kg	50,0	0,5	25,0
Material de construção	bricks	pieces	6000,0	0,075	450,0	10,0
Material de construção	cement	50 Kilo Bags	50,0	5,75	287,5	10,0
Material de construção	sand	cubic feet	52,0	0,375	19,5
Material de construção	mild steel round bar	kg	210,0	0,75	157,5
Outros	Materials Transport Cost	Lump Sum	1,0	185,0	185,0	10,0
Custos totais para a implantação da tecnologia					2501,5
Custos totais para o estabelecimento da Tecnologia em USD					2501,5

Se o usuário da terra arca com menos que 100% dos custos, indique quem cobre os custos remanescentes:

The project requested 10% contribution in kind (materials, transport, labor) from each community. The remaining costs were covered by the project.

Comentários:

The budget is for raising a 100m perimeter length of embankment.

4.5 Atividades recorrentes/manutenção

	Atividade	Periodicidade/frequência
1.	Repairing	Before onset of rains
2.	Cleaning	Before onset of rains

4.6 Custos e entradas necessárias pata a manutenção/atividades recorrentes (por ano)

	Especifique a entrada	Unidade	Quantidade	Custos por unidade	Custos totais por entrada	% dos custos arcados pelos usuários da terra
Mão-de-obra	two-monthly cleaning of filter materials	Person days	12,0	5,0	60,0	100,0
Mão-de-obra	Seasonal erosion control	Person days	12,0	5,0	60,0	100,0
Fertilizantes e biocidas	bleeching powder	bag	5,0	2,0	10,0	100,0
Custos totais para a manutenção da tecnologia					130,0
Custos totais de manutenção da Tecnologia em USD					130,0

4.7 Fatores mais importantes que afetam os custos

Descreva os fatores mais determinantes que afetam os custos:

Comparatively, construction materials costs was reflected as the most expensive consideration.

5.1 Clima

5.2 Topografia

Indique se a tecnologia é aplicada especificamente em:

• Não relevante

5.3 Solos

5.4 Disponibilidade e qualidade de água

A salinidade da água é um problema?

Sim

Especifique:

groundwater table is salty along the Bay of Bengal, salt water intrusion. Tidal surge following cyclones also creates soil salinity.

Ocorre inundação da área?

Sim

Regularidade:

Frequentemente

5.5 Biodiversidade

5.6 Características dos usuários da terra que utilizam a tecnologia

5.7 Área média de terrenos utilizados pelos usuários de terrenos que aplicam a Tecnologia

5.8 Propriedade de terra, direitos de uso da terra e de uso da água

Propriedade da terra:

• Indivíduo, não intitulado
• Indivíduo, intitulado

Direitos do uso da terra:

• Indivíduo

Direitos do uso da água:

• Acesso livre (não organizado)

5.9 Acesso a serviços e infraestrutura

6.1 Impactos no local mostrados pela tecnologia

Impactos socioeconômicos

Produção

Disponibilidade e qualidade de água

Renda e custos

Impactos socioculturais

6.2 Impactos externos mostrados pela tecnologia

6.3 Exposição e sensibilidade da tecnologia às mudanças climáticas graduais e extremos/desastres relacionados ao clima (conforme o ponto de vista dos usuários da terra)

Extremos (desastres) relacionados ao clima

Desastres climatológicos

	Como a tecnologia lida com isso?
Seca	bem

Desastres hidrológicos

	Como a tecnologia lida com isso?
Maré de tempestade/inundação costeira	muito bem

Comentários:

PSF serves as disaster resilient Technology that helps residents in coastal villages along the Bay of Bengal to cope with the effects of climate change; such as increased incidence and intensity of storms and salt water intrusion.

6.4 Análise do custo-benefício

Como os benefícios se comparam aos custos de implantação (do ponto de vista dos usuários da terra)?

Como os benefícios se comparam aos custos recorrentes/de manutenção(do ponto de vista dos usuários da terra)?

6.5 Adoção da tecnologia

• > 50%

De todos aqueles que adotaram a Tecnologia, quantos o fizeram espontaneamente, ou seja, sem receber nenhum incentivo/ pagamento material?

• 0-10%

6.6 Adaptação

A tecnologia foi recentemente modificada para adaptar-se as condições variáveis?

Não

6.7 Pontos fortes/vantagens/oportunidades da tecnologia

Pontos fortes/vantagens/oportunidades na visão do usuário da terra
The Technology is useful for supplying drinking water at household level and supports cultivation of fruit trees, medicinal plants and vegetables at the pond embankment, above the flood line.

Pontos fortes/vantagens/oportunidades na visão do/a compilador/a ou de outra pessoa capacitada
The Technology is conducive for ensuring supply of water for drinking, cooking and irrigation purposes if the community is motivated and understands the impact of PSF when faced with water shortage during dry season and other disaster events.

6.8 Pontos fracos, desvantagens/riscos da tecnologia e formas de superá-los

Pontos fracos/vantagens/riscos na visão do/a compilador/a ou de outra pessoa capacitada	Como eles podem ser superados?
Every five to six weaks, the PSF filter media needs to be maintained, requiring some training, as well organising labor and collecting petty funds for bleaching powder.	The PSF User's Manual has been translated into local language with images and tips for maintenance. This is distributed following the training. The PSF User's Committee must regularly collect user fees for smooth operations. A bank account promotes transparency. Sale of crops harvested on the embankments can help defray costs of maintenance.
Although not laborious, the hand pump requires some degree of force, and the taps are often a target of children's play.	Children should be supervised and small children must not be allowed to operate or play near the pump. Investing in sturdy tap systems is essential.
The bio-film will form after seven days of operating the pump.	Users must boil or treat water very carefully in this period.
Private owners could lose interest availing their asset for the communty. For example, they may start using the pond for fish farming in order to sustain their livelihoods.	Formal agreements with the municipality about the usage rules for the pond, and public commitments taken by the pond owners are important. Posting signboards that identify the pond as "Drinking Water Only" and specify forbidden activities is also helpful. Owners can take a higher share of crops cultivated on the embankment.

7.1 Métodos/fontes de informação

7.2 Referências às publicações disponíveis

Título, autor, ano, ISBN:

SSWM University Course Module 6: Disaster Situations: Planning and Preparedness Further Resources: Water Purification Slow Sand Filtration, Marco A. Bruni, Dorothee Spuhler (seecon international gmbh), 2012.

Disponível de onde? Custos?

https://www.sswm.info/sswm-university-course/module-6-disaster-situations-planning-and-preparedness/further-resources-0/slow-sand-filtration

Título, autor, ano, ISBN:

Pond Sand Filter (PSF) Manual – community operation and maintenance, Laxman Kharal (Terre des hommes), 2012

Disponível de onde? Custos?

Contact: info@tdh.ch

Título, autor, ano, ISBN:

Guidelines for Drinking Water Quality, 4th Edition, WHO, 2011

Disponível de onde? Custos?

http://www.who.int/water_sanitation_health/publications/2011/dwq_guidelines/en/