1.2 Detalles de contacto de las personas de referencia e instituciones involucradas en la evaluación y la documentación de la Tecnología

Nombre del proyecto que financió la documentación/ evaluación de la Tecnología (si fuera 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)

Nombre de la(s) institución(es) que facilitaron la documentación/ evaluación de la Tecnología (si fuera relevante)

Terre des Hommes (Terre des Hommes) - Suiza

1.3 Condiciones referidas al uso de datos documentados mediante WOCAT

El compilador y la/s persona(s) de referencia claves aceptan las condiciones acerca del uso de los datos documentados mediante WOCAT:

Sí

1.4 Declaración de la sostenibilidad de la Tecnología descrita

¿La Tecnología aquí descrita resulta problemática en relación a la degradación de la tierra, de tal forma que no puede considerársela una tecnología sostenible para el manejo de la tierra?

No

2.1 Breve descripción de la Tecnología

Definición de la Tecnología:

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 Descripción detallada de la Tecnología

Descripción:

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 Fotografías de la Tecnología

2.5 País/ región/ lugares donde la Tecnología fue aplicada y que se hallan comprendidos por esta evaluación

2.6 Fecha de la implementación

Si no se conoce el año preciso, indique la fecha aproximada:

• hace menos de 10 años (recientemente)

2.7 Introducción de la Tecnología

Especifique cómo se introdujo la Tecnología:

• como parte de un sistema tradicional (> 50 años)
• mediante proyectos/ intervenciones externas

3.1 Propósito(s) principal(es) de la Tecnología MST

• reducir el riesgo de desastres naturales
• adaptarse al cambio climático/ extremos climáticos y sus impactos

3.2 Tipo(s) actuales de uso de la tierra donde se aplica la Tecnología

Mezcla de tipos de uso de tierras dentro de la misma unidad de tierras: :

Sí

Especifique el uso combinado de tierras (cultivos/ pastoreo/ árboles):

• Agroforestería

3.3 ¿Cambió el uso de tierras debido a la implementación de la Tecnología?

¿Cambió el uso de tierras debido a la implementación de la Tecnología?

• No (Continúe con la pregunta 3.4)

3.4 Provisión de agua

Provisión de agua para la tierra donde se aplica la Tecnología:

• de secano

3.5 Grupo MST al que pertenece la Tecnología

• manejo de agua superficial (manantial, río, lagos, mar):

3.6 Medidas MST que componen la Tecnología

3.7 Principales tipos de degradación del suelo encarados con la Tecnología

Comentarios:

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

3.8 Prevención, reducción o restauración de la degradación del suelo

Especifique la meta de la Tecnología con relación a la degradación de la tierra:

• no aplica

4.1 Dibujo técnico de la Tecnología

4.2 Información general sobre el cálculo de insumos y costos

Especifique cómo se calcularon los costos e insumos:

• por unidad de Tecnología

Especifique la moneda usada para calcular costos:

• USD

4.3 Actividades de establecimiento

	Actividad	Momento (estación)
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

Comentarios:

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 Costos e insumos necesarios para el establecimiento

	Especifique insumo	Unidad	Cantidad	Costos por unidad	Costos totales por insumo	% de los costos cubiertos por los usuarios de las tierras
Mano de obra	Pond Excavation and Embankment Raising	Person-days	180,0	5,0	900,0	10,0
Mano de obra	Pond Fencing Works	Person-days	20,0	5,0	100,0
Mano de obra	Masonry	Person-days	36,0	6,25	225,0
Equipo	Repairing tools	Set	1,0	15,0	15,0
Equipo	Tubewell/handpump	Pieces	1,0	35,0	35,0	10,0
Equipo	Sanitary Fittings	Set	1,0	100,0	100,0
Fertilizantes y biocidas	Bleaching powder for disinfection	kg	2,0	1,0	2,0	10,0
Fertilizantes y biocidas	Lime for cleaning	kg	50,0	0,5	25,0
Material de construcción	bricks	pieces	6000,0	0,075	450,0	10,0
Material de construcción	cement	50 Kilo Bags	50,0	5,75	287,5	10,0
Material de construcción	sand	cubic feet	52,0	0,375	19,5
Material de construcción	mild steel round bar	kg	210,0	0,75	157,5
Otros	Materials Transport Cost	Lump Sum	1,0	185,0	185,0	10,0
Costos totales para establecer la Tecnología					2501,5
Costos totales para establecer la Tecnología en USD					2501,5

Si el usuario de la tierra no cubrió el 100% de los costos, indique quién financió el resto del costo:

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

Comentarios:

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

4.5 Actividades de establecimiento/ recurrentes

	Actividad	Momento/ frequencia
1.	Repairing	Before onset of rains
2.	Cleaning	Before onset of rains

4.6 Costos e insumos necesarios para actividades de mantenimiento/ recurrentes (por año)

	Especifique insumo	Unidad	Cantidad	Costos por unidad	Costos totales por insumo	% de los costos cubiertos por los usuarios de las tierras
Mano de obra	two-monthly cleaning of filter materials	Person days	12,0	5,0	60,0	100,0
Mano de obra	Seasonal erosion control	Person days	12,0	5,0	60,0	100,0
Fertilizantes y biocidas	bleeching powder	bag	5,0	2,0	10,0	100,0
Indique los costos totales para mantenecer la Tecnología					130,0
Costos totales para mantener la Tecnología en USD					130,0

4.7 Factores más determinantes que afectan los costos:

Describa los factores más determinantes que afectan los costos:

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

5.1 Clima

5.2 Topografía

Indique si la Tecnología se aplica específicamente en:

• no relevante

5.3 Suelos

5.4 Disponibilidad y calidad de agua

¿La salinidad del agua es un problema?

Sí

Especifique:

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

¿Se está llevando a cabo la inundación del área? :

Sí

Frecuencia:

frecuentemente

5.5 Biodiversidad

5.6 Las características de los usuarios de la tierra que aplican la Tecnología

5.7 Área promedio de la tierra usada por usuarios de tierra que aplican la Tecnología

5.8 Tenencia de tierra, uso de tierra y derechos de uso de agua

Tenencia de tierra:

• individual, sin título
• individual, con título

Derechos de uso de tierra:

• individual

Derechos de uso de agua:

• acceso abierto (no organizado)

5.9 Acceso a servicios e infraestructura

6.1 Impactos in situ demostrados por la Tecnología

Impactos socioeconómicos

Producción

Disponibilidad y calidad de agua

Ingreso y costos

Impactos socioculturales

6.2 Impactos fuera del sitio demostrados por la Tecnología

6.3 Exposición y sensibilidad de la Tecnología al cambio climático gradual y a extremos relacionados al clima/ desastres (desde la percepción de los usuarios de tierras)

Extremos (desastres) relacionados al clima

Desastres climatológicos

	¿Cómo es que la tecnología soporta esto?
sequía	bien

Desastres hidrológicos

	¿Cómo es que la tecnología soporta esto?
marea tormentosa/ inundación costera	muy bien

Comentarios:

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 Análisis costo-beneficio

¿Cómo se comparan los beneficios con los costos de establecimiento (desde la perspectiva de los usuarios de tierra)?

¿Cómo se comparan los beneficios con los costos de mantenimiento/ recurrentes (desde la perspectiva de los usuarios de tierra)?

6.5 Adopción de la Tecnología

• > 50%

De todos quienes adoptaron la Tecnología, ¿cuántos lo hicieron espontáneamente, por ej. sin recibir nada de incentivos/ materiales:

• 0-10%

6.6 Adaptación

¿La tecnología fue modificada recientemente para adaptarse a las condiciones cambiantes?

No

6.7 Fuerzas/ ventajas/ oportunidades de la Tecnología

Fuerzas/ ventajas/ oportunidades desde la perspectiva del usuario de la tierra
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.

Fuerzas/ ventajas/ oportunidades desde la perspectiva del compilador o de otra persona de referencia clave
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 Debilidades/ desventajas/ riesgos de la Tecnología y formas de sobreponerse a ellos

Debilidades/ desventajas/ riesgos desde la perspectiva del compilador o de otra persona de referencia clave	¿Cómo sobreponerse a ellas?
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/ fuentes de información

7.2 Vínculos a las publicaciones disponibles

Título, autor, año, 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.

¿Dónde se halla disponible? ¿Costo?

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

Título, autor, año, ISBN:

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

¿Dónde se halla disponible? ¿Costo?

Contact: info@tdh.ch

Título, autor, año, ISBN:

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

¿Dónde se halla disponible? ¿Costo?

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