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Newsletter and Technical Publications 1.5.3 Water Energy Long before the introduction of pumps, Arabs have used various means of large-scale pumping and conveying of water for irrigation and other purposes. This is especially true for Lebanon, Syria and Iraq, as well as the plains of the Degla, Al-Furate, Al-Khabour and Al-Aasy rivers. One of the most important method is the water wheel (also known as Al-Na’aour in Iraq). Many still exist and are operating on the plains of the Al-Aasy and Al-Khabour rivers (Syria) and Al-Furat (Iraq) (Figure 39). It is considered a useful technology for lifting water from channels and rivers with an unconventional energy source. Some water wheels are operated by water power, while others are operated with the use of animals. This report only discusses the technology operated by water power. Technology Description Water wheels are basically made of wood from different types of trees, and are known by three different names in Arab heritage. They are called the Al-Dolab (the Disc), Al-Saqiah (the Irrigating) and Al-Na’aoura (the Screaming), referring to their shape, mode of operation and sound, respectively. A water power-driven water wheel consists of a vertical disc of large diameter (5-21 m) equipped with pedals and buckets distributed along its perimeter. The disc is rotated by the flowing water in the stream, lifting the water upwards. The water wheel used to be made of a large wooden ring, with a diameter sometimes exceeding 10 m. The inside perimeter of the ring is attached to its center with wooden rods made of large tree stems, strongly tied around a strong, durable wood shaft (known as the heart in Syria). The disc is supported by two large pieces of wood (Al-Kaft) supported by two rock blocks constructed perpendicular to the direction of the river flow (Figure 40). A series of clay or wooden buckets are arranged along the ring’s outside perimeter. When the flowing water rotates the disc, the lower buckets fill with water and are moved upwards, to pour the water into channels. The channels are constructed at levels approximately equal to the radius of the water wheel, above the water surface. The channels are constructed with a gradual slope to reach the ground surface. The allows the water to be conveyed through the irrigation channels to agricultural fields. The rotation velocity of the disc increases with increasing velocity of the flowing water. Thus, the most appropriate locations to install the water wheel is in places where the water stream is narrowest, thereby causing the water velocity to reach the highest value. In areas of low flow velocities, animals (mules and ox) are used to lift the water. This approach is known as the animal water wheel. It has different forms, but is based on the anima walking in circles around a shaft that transfers the movement energy to the water wheel via gears.
Extent of Use This technology is still used on a small scale in Hamah, in Syria, where there are currently 23 water wheels. It also is used in some areas on the plains of Al-Furat River, south of Iraq. In general, however, the technology is being replaced by the use of diesel or electric pumps. Operation and Maintenance Operation of this technology is based on transforming energy from one form to another. The flowing stream water supplies kinetic energy to the disc, by rotating the water wheel pedals fixed around the disc as they capture the water flow. This kinetic energy is thereby transformed into mechanical energy via the water wheel shaft, thus rotating the disc. When the disc and its buckets rotate, the mechanical energy is transformed into potential energy, lifting the full buckets from the stream channel to the level of the emptying basin. Water wheel maintenance depends on the manufacturing method, the materials used and the rotation speed. Since water wheels operate continuously, they typically require partial restoration of the worn wood each year, and sometimes a complete restoration every three years. Fortunately, this is not typically a major effort, and is done in a simple, relatively inexpensive manner in the workshops where the water wheel was initially manufactured. Level of Involvement This technology has become somewhat of a historic technology. It could possibly disappear as a viable technology, due to the introduction of new technologies based on oil or electricity. However, due to its simplicity, efficiency and low operating and maintenance costs, there is no doubt that this technology deserves further attention and consideration. To this end, the Syrian government is focusing attention on existing water wheels on the Al-Aasy river in Hamah (formerly known as “the water wheel city”), and a new governmental department has recently been created to manage the operation and maintenance of these water wheels. Costs The construction costs of this technology depend on the complexity, size and type of manufacturing wood of its components. Because workshops for producing this technology do not exist, the construction costs cannot presently be accurately estimated. Effectiveness of the Technology The effectiveness of this technology depends on the water flow velocity, increasing with increasing velocity. Its effectiveness also depends on the size of the water wheel, which can range between 5-12 m. Larger water wheels can lift water to higher levels. A larger number of buckets, which can range between 50-120, also can lift larger volumes of water. The water wheel discharge can vary on the basis of its diameter, volume of its bucket, and the stream velocity (which can reach values up to 650 m3/s). Suitability The technology is considered suitable for lifting water from continuous-flow channels and rivers. It has proven beneficial throughout the ages for irrigation works in Syria, Lebanon and Iraq. It also was widely used on the Al-Aasy river in Syria and Al-Furat river in Iraq. It is considered an environmentally-clean, efficient and inexpensive technology, worthy of increased attention. Advantages The advantages of this technology are as follows:
Disadvantages The disadvantages of this technology are as follows:
Cultural Acceptance If efforts were made to revive and encourage this technology, no feasible obstacles exist to prevent its acceptance. Under appropriate conditions, it might be possible it to revive it to the extent that it could compete with advanced technology, particularly since it does not have the associated fuel or maintenance requirements. Further Development of the Technology The technology can be improved by introducing new manufacturing materials that are easier to install and dismantle, that are durable and cheap, similar to what is being done with windmills for lifting water with the use of wind energy. Its use also would be facilitated by replacing some of its wooden parts with cheaper and more durable materials (steel shafts, fiberglass rings, plastic buckets, etc). Information Sources Contacts Abdullah Al-Masry Naufal Abdel-Gabbar Al-Masry References Naufal Abdel Gabbar Al-Masry. 1999. State Report, Project for Preparation of the Source Book for the Alternative Technologies for Freshwater Augmentation in the Arab Countries of West Asia Region. ACSAD, Damascus, Syria. ACSAD. 1983. Study and development project of Arab water technologies, State Report – Syria. ACSAD/HS/T29, Damascus, Syria. UNESCO/ACSAD. 1986. Major regional project on rational utilization and conservation of water resources in the rural areas of the Arab States, with emphasis on traditional water systems. Technical report, UNESCO/ACSAD, Damascus, Syria. Walid Qonbaz. 1996. Water wheels: The symbol and story of its manufacturing. Al-Faisal Journal, vol. 237, Saudi Arabia.
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