Roof top rainwater harvesting stored in a polythene lined earth retention tank. [塔吉克斯坦]
- 编制者： Daler Domullojonov
- 编辑者： –
- 审查者： David Streiff
Чамъоварии оби борон аз руи боми хона
technologies_1446 - 塔吉克斯坦
有助于对技术进行记录/评估的机构名称（如相关）Deutsche Welthungerhilfe - 塔吉克斯坦
有助于对技术进行记录/评估的机构名称（如相关）Pilot Program for Climate Resilience Tajikistan (PPCR Tajikistan) - 塔吉克斯坦
The use of an earth tank lined with a polyethylene sheet to retain rainwater collected from the roof of the house.
An earth retention tank is a simple low cost structure that can be used to retain rain water from the rooftop. A hole is prepared and lined with a polyethylene sheet to prevent leakage. The top of the hole is covered with a metal lid for access. The roof of the house is fitted with a plastic guttering that captures the rainwater and funnels the water via a plastic pipe into the earth tank. The water in the earth tank then can be utilised for the irrigation of crops (especially during the hot dry summer months), sanitation, and potentially drinking water.
Purpose of the Technology: The population in Southern Tajikistan consists largely of subsistance farmers and are thus highly reliant upon their kitchen garden plots. As the population in the area continues to expand, the pressure on the land increases. The latter is already in a poor state, because it is becoming degraded through deforestation, overgrazing and general over exploitation. There is much precipitation during the rainy season from autumn until spring in Southern Tajikistan, but the scarcity of water from late spring to the end of autumn poses a problem with water shortages.
During the rainy season, a lot of water is lost as surface runoff, this water can be saved in a retention tank to be utilised during the dry season. It can be used to water crops to help increase yields as well as crop diversity and quality. The additional water can also be used for sanitation, drinking water and watering of livestock.
Establishment / maintenance activities and inputs: For the establishment of such a retention tank several steps are needed. In preparation, a rough estimation of the potential volume of harvested rainwater needs to be calculated. Thereafter, a location for the tank needs to be selected so that expenses are minimised and it is easy to access. The establishment of ponds near big trees is not recommended, because the polyethylene layer might be punctured by the roots.
Natural / human environment: The actual steps of constructing the tank involve:
(1) digging the pond, (2) plastering the inside walls with a fine soil and water mixture to smooth them, (3) lining the pond’s walls with double polyethylene layer, (4) connecting the inside polyethylene sheets with the pond coverage through a piece of cord, so that it can be taken out of the pond any time to be cleaned of sediments, (5) covering the pond with any available material such as a soil, water and straw mixture, reinforced by several poles, leaving an opening of 0.25 x 0.25m to extract water, (6) finally connecting the roof to the pond with a plastic pipe. To avoid dirty water flowing from the roof into the pond, the pipe should only be connected to the pond some time after the rainfall has started.
The technology was developed through a Welthunger Hilfe Project and promotion in the local communities started in 2008.
Major land use problems (compiler’s opinion): Inefficient natural resource management, which is mainly visual because people throw potential organic fertilisers away instead of spreading them on the fields. Incorrect ploughing techniques which leads to the acceleration of erosion, deforestation and waste of fuel materials in inefficient stoves and ovens. Overgrazing leading to pasture degradation.
Major land use problems (land users’ perception): lack of water
Constraints of settlement / urban
Longest growing period in days: 180Longest growing period from month to month: March - November
- 10-100 平方千米
Main measures: structural measures
Main type of degradation addressed: Ha: aridification, Hs: change in quantity of surface water, Hp: decline of surface water quality
Main causes of degradation: soil management (Inproper land management), deforestation / removal of natural vegetation (incl. forest fires) (Cutting trees and shrubs), overgrazing, inputs and infrastructure: (roads, markets, distribution of water points, other, …) (poor water supply)
Secondary causes of degradation: population pressure (the population is increasing over time.), poverty / wealth (lack of funds)
Main goals: rehabilitation / reclamation of denuded land
Secondary goals: prevention of land degradation, mitigation / reduction of land degradation
Daler Domullojonov, 14, Giprozem str., Dushanbe, Tajikistan
Harvesting water from the household roof to an earth built retention pond with plastic sheet lining. The retention pond is covered with a removable metal plate for access.
Location: Davad village, Vatan jamoat, Temurmalik district,. Khatlon province, Tajikistan
Date: June 2009
Technical knowledge required for field staff / advisors: low (No special knowledge is needed for implementation)
Technical knowledge required for land users: moderate (Any farmer can implement, once they understand the basic concept.)
Main technical functions: control of concentrated runoff: retain / trap, control of concentrated runoff: drain / divert, water harvesting / increase water supply
Dam/ pan/ pond
Depth of ditches/pits/dams (m): 3.5
Width of ditches/pits/dams (m): 1.2
Length of ditches/pits/dams (m): 1.2
Construction material (earth): digging in earth, plastering and cover
Construction material (wood): pole for cover
Construction material (other): polyethelene sheets, plastic pipe
Specification of dams/ pans/ ponds: Capacity 3.96m3
Catchment area: 72 m2m2
Beneficial area: 0.2h.am2
For water harvesting: the ratio between the area where the harvested water is applied and the total area from which water is collected is: 1:0.5
|1.||Manual digging of pond;smoothing and plastering;covering pond||结构性的||once in the beginning|
|2.||polyethylene sheet and pipe procurement, preparation and placement;||结构性的||once in the beginning|
|劳动力||Manual digging of pond||Persons/day||2.0||30.0||60.0||100.0|
|施工材料||Wooden poles for pond||poles||4.0||5.0||20.0||100.0|
|施工材料||Polyethylene sheet||square meters||10.0||2.3||23.0||50.0|
Duration of establishment phase: 24 month(s)
|1.||Cleaning of pond (washing out sediments)||结构性的||once every year|
|2.||Changing polyethylene sheet;covering||结构性的||once every 2 years|
|3.||Changing polyethylene sheet;covering||管理||once per 2 years|
|劳动力||Cleaning of pond (washing out sediments)||Persons/day||0.1||45.0||4.5||100.0|
|劳动力||Changing polyethylene sheet (every 2 years)||Persons/day||1.0||10.0||10.0||100.0|
|施工材料||Polyethylene sheet||square meters||10.0||2.3||23.0||100.0|
The above costs were calculated for the building of one retention tank. One household could have several ponds in one kitchen garden.
The type of earth in Tajikistan is very good for making the retention ponds, the labour is provided by the land user, and the plastic pipes can be manufactured out of empty plastic bottles. The polythene sheet and cord have to be purchased from the shop.
- < 250毫米
- > 4,000毫米
Average annual precipitation is 575 mm (according to data from the last 15 years), most of which falls between late autumn and spring time.
Thermal climate class: temperate. 3 months below 5 degrees, 7 months above 10 degrees
- 0-100 m a.s.l.
- 101-500 m a.s.l.
- 501-1,000 m a.s.l.
- 1,001-1,500 m a.s.l.
- 1,501-2,000 m a.s.l.
- 2,001-2,500 m a.s.l.
- 2,501-3,000 m a.s.l.
- 3,001-4,000 m a.s.l.
- > 4,000 m a.s.l.
Altitudinal zone: Mainly communities in this range
- 非常深（> 120厘米）
Soil fertility is medium and if it is not overused the fertility can be increased.
Topsoil organic matter: Usually locals collect cow dung and use it as fuel.
Soil drainage / infiltration is medium
Soil water storage capacity is medium because the loess material contains clay material
Ground water table can also be below 50 m.
Availability of surface water is so poor du to deforestation the natural water balance is disturbed.
Land users applying the Technology are mainly common / average land users
Population density: < 10 persons/km2
Annual population growth: 1% - 2%
100% of the land users are poor.
Off-farm income specification: In this example the farmer's son has migrated to Russia.
- < 0.5 公顷
- 0.5-1 公顷
- 1-2 公顷
- > 10,000公顷
Water storing capacity of household increased
vegetables and greens are available for own consumption
no need to carry water
Livelihoods and human well-being
more water available
more water available
only in kitchen garden
To minimise the damage to the polyethylene waterproofing layers and, reduce evaporation rates, pond is covered. As the pond is dug into earth the temperature remains fairly stable. If precipitation decreases less water can be harvested.
Before the implementation of this technology, one family would spend an avarage of $44.5 on one truck of water per month. A pond costs around $25 to build, and should provide families with around 4 months worth of water after the rainy season.
- 大于 50%
600 households (in an area of 10-100km^2)
58% of land user families have adopted the Technology with external material support
350 land user families have adopted the Technology with external material support
Comments on acceptance with external material support: In the initial stages of the project, they were provided with 50% of the costs of the polyethylene sheets and cord only.
42% of land user families have adopted the Technology without any external material support
250 land user families have adopted the Technology without any external material support
Comments on spontaneous adoption: After observing the benefits of the technology and the high cost benefit ratio, many people in the community and surrounding villages have replicated this technology themselves.
There is a strong trend towards spontaneous adoption of the Technology
|Easy and quick to establish, and maintain.|
It is a low cost technology and can be made from many locally available materials.
How can they be sustained / enhanced? To disseminate these ideas in areas with water scarcity through local Extension Service providers / NGOs or local inhabitants.
It reduces the time and effort to collect water and also the cost to buy water.
How can they be sustained / enhanced? Promotion of different water saving methods and technologies by interested and line departments.
|More water available for gardening and household purposes|
Increases access to water for drinking and sanitation purposes.
How can they be sustained / enhanced? Construction of larger and/or more tanks.
Provides water for irrigation during the hot dry months, therefore improving crop diversity and yields.
How can they be sustained / enhanced? Training and education on kitchen garden farming techniques to optimise the use of the extra water supply.
|The polyethylene only lasts for 2-4 years.||To increase the number of layers or use a thicker polyethylene sheet|
|The plastic layers have a limited lifespan.||To find thicker and more hardy materials, or apply multiple layers.|
|Th waterproof layer can easily be degraded by mice and large insects.|
Brochure - Converting drought prone areas into productive gardens! Low cost options to improve rainwater harvesting in Southern Tajikistan rain fed areas …. and beyond! 2009
Welthungerhilfe, Temurmalik office,
Training film - Simple ways to improve management of kitchen gardens in Southern Tajikistan rain fed areas …. and beyond. 2009
Welthungerhilfe, Temurmalik office
Welthungerhilfe project final narrative report (144-912) - 2010
Welthungerhilfe, Temurmalik office