Khun Lean Hak
有助于对技术进行记录/评估的机构名称（如相关）Society for Community Development in Cambodia (SOFDEC) - 柬埔寨
有助于对技术进行记录/评估的机构名称（如相关）Local Agricultural Research and Extension Centre (LAREC) - 柬埔寨
Norias are water-pumping wheels made of bamboo which are used to irrigate paddy fields in order to increase the yield.
Norias are undershot waterwheels used to pump up water. They are a traditional technology in south-east Asia, where the technology is passed on from father to son. Norias are traditionally made of bamboo and wood. The stream powers the wheel; the bamboo tubes closed at one end fill with water, carry it up and release it in a trough which flows to the fields. To avoid damages from floating debris and water plants, a diverting bamboo fence is built upstream.
When the water level in the river is lower, an underwater bound is built to direct it toward the wheel and ensure a continuous pumping. This is done around three times a year. In case of a flood, the waterwheel can be damaged or destroyed, which occurs around once a year. The noria described in this case study is in use from June to November, as the river dries out. With its 3 m diameter it allows the production of two rice harvests a year on 2.5 ha. During the dry season, it is removed and repaired.
The purpose of this irrigation device is to ensure a permanent water access in the rice field, and to produce 2 harvests instead of one per year. The norias are low cost devices which are built by the farmer themselves, but can only be used to irrigate fields which are located close to a river.
To build a noria, an experienced farmer only needs around one day, and wood and bamboo worth around 25 US$. It is installed at the beginning of the rainy season, and removed at the end to be fixed. In case of floods (which happens around once a year) it also needs to be fixed. The maintenance costs are around a quarter of the establishment costs. When the water level drops, a berm is built in the water to redirect the water toward the wheel, which is needed around three times a year. With this berm, the speed and thus pumping of water can be regulated.
The analysed area is flat (slope < 2%), with a tropical climate (dry and wet season), and the soils are mostly sandy or loamy. The soils contain little organic matter (low soil fertility, acidification, small amount of cattle, area has been deforested a long time ago) and the groundwater table is rather high (2 m below soil level during the dry season, on the surface during the wet season). There are many temporary and a few permanent streams in the area.
Due to climate change, the rainfalls are more erratic, temperatures rise and droughts are more recurrent. Rice is the predominant crop grown in the area, since it serves as staple food (mix subsistence and commercial activities). Rice is often grown in monocultures and harvested once a year. Once the rice is harvested (dry season), some farmers release cattle to the paddy fields to eat the straw and weeds.
As an addition to rice, most land users grow vegetables and fruits in small home gardens (subsistence) and complement their income by producing handicrafts or through off-farm income / remittances from family members working in other places. The increasing migration rate (the young generation leaves the villages to work in the cities, garment industry or abroad) results in a decrease of available labour force in the area which has detrimental effects on the agricultural activities. Furthermore, the civil war in the 1970s (Khmer Rouge) led to the loss of agricultural knowledge which different NGOs try to re-establish.
- 0.1-1 平方千米
- 作为传统系统的一部分（> 50 年）
Norias are a traditional setting in south-east Asia. The farmer from this case study learned it from his father, and the family continuously used them for generations (except during the Pol Pot regime).
年作 - 具体指明作物:
- 谷类 - 水稻（湿地）
Longest growing period in days: 210, Longest growing period from month to month: June-December
Major land use problems (compiler’s opinion): Low soil fertility, lack of irrigation, monocultures, overgrazing, soil left bare after ploughing.
Major land use problems (land users’ perception): Lack of irrigation.
Livestock is grazing on crop residues
Main causes of degradation: soil management, crop management (annual, perennial, tree/shrub) (Rice monocultures, with soil left bare after ploughing.), droughts (More erratic rainfall.)
Secondary causes of degradation: overgrazing (Uncontrolled grazing of cattle.), change in temperature (More hot days.)
Noria, undershot water wheel lifting up water. The stream pushes the wheel, while the bamboos closed on one side are filled with water which is released into the trough where it flows to the fields.
Technical knowledge required for field staff / advisors: high
Technical knowledge required for land users: low (This is the farmers opinion. He said building norias is easy, everybody in the village could build them. On the other hand, only farmers who learned it from their father use it.)
Main technical functions: water harvesting / increase water supply
Secondary technical functions: increase of biomass (quantity)
Structural measure: Noria
Construction material (earth): The bank is built in the river when the water level is low to divert the water toward the wheel.
Construction material (wood): Bamboo fence in the water to avoid damages by floating plants or waste.
Beneficial area: 2.5 ham2
FAO, Rome, http://www.fao.org/docrep/010/ah810e/AH810E05.htm
|1.||Build and install the noria.|
|1.||Repair and reinstall the water wheel||Yearly, at the wet season of the dry season and after the floods.|
|2.||Build a small bound inside the river to redirect the water toward the noria||When the water level sinks, approximately 3 times/year|
Machinery/ tools: hatchet, saw, drill
The costs were calculated in 2014 for a noria of around 3 m diameter, irrigating 2.5 ha of rice fields.
The availability of wood and bamboo determines the costs.
- < 250毫米
- > 4,000毫米
1486.45 mm 2013 in Kampong Chhnang
Thermal climate class: tropics. 27-35°C
- 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.
- 非常深（> 120厘米）
during dry seasons
Land users applying the Technology are mainly common / average land users
Difference in the involvement of women and men: Heavy labour, and skills are passed on from father to son.
Population density: 10-50 persons/km2
Annual population growth: 0.5% - 1% (Rich farmers use pumps, poor farmers do not have land near the river.).
Off-farm income specification: Handicraft, remittances, and factory work.
- < 0.5 公顷
- 0.5-1 公顷
- 1-2 公顷
- > 10,000公顷
Land users have a title that is not recognized by the state.
2 rice harvests instead of one.
No problems during dry season.
Same land twice under use.
Pumps are around 10 times more expensive to rent.
2 harvests, without risk of failure due to drought.
contribution to human well-being
2 rice harvests instead of one improves the livelihood of the farmers applying this technology.
Decreased water availability in the river.
Period of production is increased.
100% of land user families have adopted the Technology without any external material support
5 land user families have adopted the Technology without any external material support
There is no trend towards spontaneous adoption of the Technology
The suitable water streams are given, norias can only irrigate areas close to streams.
|The river water quality (nutrients) is higher than the quality of rainwater for the irrigation of crops.|
|Through the use of Norias there is always water in the paddy fields; the rice is less threatened by droughts|
|There are two rice harvests each year instead of one.|
|Norias are much cheaper (around 10 times) than renting a water pump.|
|Fields are only irrigated when sufficient water is available, thus not depleting the river of all its water, as norias need a rather high water flow rate.|
|Do not rely on fossil fuels.|
|Norias are damaged/destroyed in case of floods.||A weather forecast system would allow to remove/secure the noria in case of a flood.|
|The fields need to be close to a stream, at a distance of max. 100 m as a noria does not pump much water.||Use SRI (System of Rice Intensification) with alternately flooding and drying the fields.|
FAO report on water pumping devices.