1.2 参与该技术评估和文件编制的资源人员和机构的联系方式

有助于对技术进行记录/评估的项目名称（如相关）

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)

有助于对技术进行记录/评估的机构名称（如相关）

Terre des Hommes (Terre des Hommes) - 瑞士

1.3 关于使用通过WOCAT记录的数据的条件

（现场）数据是什么时候汇编的？:

16/08/2016

编制者和关键资源人员接受有关使用通过WOCAT记录数据的条件。:

是

1.4 所述技术的可持续性声明

这里所描述的技术在土地退化方面是否存在问题，导致无法被认为是一种可持续的土地管理技术？:

否

2.1 技术简介

技术定义:

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 技术的详细说明

说明:

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 技术照片

2.5 已应用该技术的、本评估所涵盖的国家/地区/地点

2.6 实施日期

如果不知道确切的年份，请说明大概的日期:

• 不到10年前（最近）

2.7 技术介绍

详细说明该技术是如何引入的:

• 作为传统系统的一部分（> 50 年）
• 通过项目/外部干预

3.1 该技术的主要目的

• 降低灾害风险
• 适应气候变化/极端天气及其影响

3.2 应用该技术的当前土地利用类型

3.3 有关土地利用的更多信息

该技术所应用土地的供水:

• 雨养

每年的生长季节数:

• 2

3.4 该技术所属的SLM组

• 地表水管理（泉、河、湖、海）

3.5 技术传播

具体说明该技术的分布:

• 适用于特定场所/集中在较小区域

注释:

This technology may be applied to selected ponds within a community.

3.6 包含该技术的可持续土地管理措施

3.7 该技术强调的主要土地退化类型

注释:

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

3.8 防止、减少或恢复土地退化

具体数量名该技术与土地退化有关的目标:

• 不适用

4.1 该技术的技术图纸

4.2 技术规范/技术图纸说明

PSF is built on top of the raised embankment as a reinforced concretes structure consisting of a sand filter chamber, filtered water chamber and the sedimentation tank. The height is 4 feet 2 inches; Length-14 feet 5 inches; Width-7 feet. The capacity of PSF is 2500 liters. The construction materials used include include brick, sand, brick chips, cement, galvanized iron pipe, water tap and rebar.

The medium in the filter chamber shall comprise of three layers: 1) filter sand of 2 feet (60 cm) depth placed above 2) a 3” layer of fine gravel and 3) a 3" layer of coarse gravel.
1) The filter sand shall have the following size and grade: (a) Sand grains in the range 0.1 to 1 mm, with (b) effective size ( d10) in the range 0.15 to 0.20; and (c) Uniformity Coefficient ( d60/d10) in the range 1.5 to 2.5. Sieves are used to test sand size and grade.
The "under drainage" bottom gravel layers:
2) Fine gravel: 3” layer ¼” to 1 mm grains (gravel that passes through the ¼” sieve and are retained on 1 mm sieve)
3) Coarse gravel: 3" layer of ½” to ¼” grains (gravel that passes through ½” sieve and are retained on ¼” sieve)
Use different sized sieves made of wire mesh in wooden frame to prepare the media to prepare the two layers of gravel.

Every 5-6 weeks (or when flow rate is limited) cleaning the filter should be performed. Remove the filter aggregate layers, clean the PSF by removing any remaining objects in the three chambers (sand filter chamber, filtered water chamber and the sedimentation tank). Clean these chambers thoroughly using hard brush in necessary. Sequentially clean and replace t the coarse gravel media, then the fine gravel media, and finally the filter sand. For cleaning the gravel and sand place about 1/4th bucket of grave or the sand in plastic bucket (8, 10 or 12 liters, whichever may be convenient), pour about ½ bucket of water and then wash lifting the gravel or the sand from the bottom with hand several times, then decant the water by tilting the bucket. (Only fine particles less than 0.1 mm should be poured out while washing the sand.)

Raised Pond embankments are built with earthworks of clayey soils designed per the maximum flood height. The design depicted in this section is an indication, however the services of a qualified structural/civil engineer will be required. In general building the embankment is raised 0.6m above the maximum flood level is recommended, at a slope of 1:2. From the ground level, the average height of an embankment is two meters, and the average excavation depth is also two meters. All plans for both embankment works and PSF construction were reviewed and approved by the Bangladesh Government Department of Public Health and Engineering.

4.3 有关投入和成本计算的一般信息

具体说明成本和投入是如何计算的:

• 每个技术单元

具体说明成本计算所用货币:

• 美元

4.4 技术建立活动

	活动	措施类型	时间
1.	Community consultation for Committee Formation	管理	Before onset of rain
2.	Create PSF Users' Committee, agre on user contributions	管理	Before onset of rain
3.	Committee / pond selection approved by local Government	管理	Before onset of rain
4.	Technical orientation to PSF Committee, input on designs	管理	Before onset of rain
5.	Excavation of Pond	结构性的	Before onset of rain
6.	Embankment Construction	管理	Before onset of rain
7.	PSF Construction	结构性的
8.	Fencing	结构性的
9.	Turfing and hortiuclutre on the embankment	农业学的	Before onset of rain
10.	PSF Training on Media Selection and maintenance	管理	Regular intervals throughout the year (every 1-2 months)
11.	Pond embankment maintenance	结构性的	Before onset of rain

注释:

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.

4.5 技术建立所需要的费用和投入

	对投入进行具体说明	单位	数量	单位成本	每项投入的总成本	土地使用者承担的成本%
劳动力	Pond Excavation and Embankment Raising	Person-days	180.0	5.0	900.0	10.0
劳动力	Pond Fencing Works	Person-days	20.0	5.0	100.0
劳动力	Masonry	Person-days	36.0	6.25	225.0
设备	Repairing tools	Set	1.0	15.0	15.0
设备	Tubewell/handpump	Pieces	1.0	35.0	35.0	10.0
设备	Sanitary Fittings	Set	1.0	100.0	100.0
肥料和杀菌剂	Bleaching powder for disinfection	kg	2.0	1.0	2.0	10.0
肥料和杀菌剂	Lime for cleaning	kg	50.0	0.5	25.0
施工材料
施工材料
施工材料	bricks	pieces	6000.0	0.075	450.0	10.0
施工材料	cement	50 Kilo Bags	50.0	5.75	287.5	10.0
施工材料	sand	cubic feet	52.0	0.375	19.5
施工材料	mild steel round bar	kg	210.0	0.75	157.5
其它	Materials Transport Cost	Lump Sum	1.0	185.0	185.0	10.0
技术建立所需总成本					2501.5

如果土地使用者负担的费用少于100%，请注明由谁负担其余费用:

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

注释:

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

4.6 维护/经常性活动

	活动	措施类型	时间/频率
1.	Repairing	其它措施	Before onset of rains
2.	Cleaning	管理	Before onset of rains

4.7 维护/经常性活动所需要的费用和投入（每年）

	对投入进行具体说明	单位	数量	单位成本	每项投入的总成本	土地使用者承担的成本%
劳动力	two-monthly cleaning of filter materials	Person days	12.0	5.0	60.0	100.0
劳动力	Seasonal erosion control	Person days	12.0	5.0	60.0	100.0
肥料和杀菌剂	bleeching powder	bag	5.0	2.0	10.0	100.0
技术维护所需总成本					130.0

4.8 影响成本的最重要因素

描述影响成本的最决定性因素:

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

5.1 气候

5.2 地形

说明该技术是否专门应用于:

• 不相关

5.3 土壤

5.4 水资源可用性和质量

水的盐度有问题吗？:

是

具体说明:

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

该区域正在发生洪水吗？:

是

规律性:

频繁

5.5 生物多样性

5.6 应用该技术的土地使用者的特征

5.7 应用该技术的土地使用者拥有或租用的平均土地面积

5.8 土地所有权、土地使用权和水使用权

土地所有权:

• 个人，未命名
• 个人，有命名

土地使用权:

• 个人

用水权:

• 自由进入（无组织）

5.9 进入服务和基础设施的通道

6.1 该技术的现场影响

社会经济效应

生产

水资源可用性和质量

收入和成本

社会文化影响

6.2 该技术的场外影响已经显现

6.3 技术对渐变气候以及与气候相关的极端情况/灾害的暴露和敏感性（土地使用者认为的极端情况/灾害）

气候有关的极端情况（灾害）

气候灾害

	该技术是如何应对的？
干旱	好

水文灾害

	该技术是如何应对的？
风暴潮/沿海洪水	非常好

注释:

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 成本效益分析

技术收益与技术建立成本相比如何（从土地使用者的角度看）？

技术收益与技术维护成本/经常性成本相比如何（从土地使用者的角度看）？

6.5 技术采用

• 大于 50%

在所有采用这项技术的人当中，有多少人是自发地采用该技术，即未获得任何物质奖励/付款？:

• 0-10%

6.6 适应

最近是否对该技术进行了修改以适应不断变化的条件？:

否

6.7 该技术的优点/长处/机会

土地使用者眼中的长处/优势/机会
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.

编制者或其他关键资源人员认为的长处/优势/机会
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 技术的弱点/缺点/风险及其克服方法

编制者或其他关键资源人员认为的弱点/缺点/风险	如何克服它们？
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 信息的方法/来源

7.2 参考可用出版物

标题、作者、年份、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.

可以从哪里获得?成本如何?

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

标题、作者、年份、ISBN:

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

可以从哪里获得?成本如何?

Contact: info@tdh.ch

标题、作者、年份、ISBN:

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

可以从哪里获得?成本如何?

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