Sourcebook of Alternative Technologies for Freshwater Augumentation in East and Central Europe


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<Sourcebook of Alternative Technologies for Freshwater Augumentation in East and Central Europe>

PART B - ALTERNATIVE TECHNOLOGIES

1. FRESHWATER AUGMENTATION TECHNOLOGIES

1.1 Drip-irrigation System

Technical Description

Drip irrigation systems allow the more efficient use of water in agriculture. Water in the system is distributed directly to each cultivated plant and dosed in a controlled manner by drippers. The main components of such a system include the sprinkler lateral and its parts; the dripper lines; a pressure compensator; pressure and water quantity metering instruments; water treatment facilities and fertilizer injectors; and, automation systems, if used. The most refined technologies have an integrated multi-system controller, including computerized micro-climate weather monitoring sensors, humidity and temperature sensors, and computerized control of rates of irrigation and fertilization. This technology provides precision irrigation monitoring, accurate irrigation direct to the point of greatest water need, and controlled fertilization.

Extent of Use

Irrigation is very important in providing water for agriculture in Hungary, Bulgaria, and Romania. As a consequence of the unusually long drought in the region, which lasted from the early eighties until 1993, countries such as have developed and implemented increasing numbers of drip irrigation systems as an economical, water saving and effective method of irrigation. For example, in Hungary, the extent of drought prompted the development and implementation of a "drought index", the PAI, which is calculated in terms of relative temperature and precipitation, and which reflects the monthly change in the water demands of crops (and, indirectly, the position of the groundwater tables). In 1993, the national average value of PAI drought index was 9 C/100 mm, indicative of heavy drought conditions. The drought affected 78 000 km², or 84% of the total area of the country. Of this area, 8 274 ha were considered to be technically equipped for the application of supplemental water through irrigation, but only 4 847 ha were actively irrigated. Given these circumstances, there was a great need to find the most effective method for application of irrigation waters, and, as a result, more and more of these drip irrigation systems were developed and put into practice in Hungary during the 1990s.

Operation and Maintenance

Depending on the size of the irrigation scheme and complexity of the system design, the principle operating requirements include standard control, repair, and adjustment procedures. System design parameters should be planned on the basis of climatic data, physiographical relief, hydrological data, soil conditions, type of cultivation, crop water demand, and irrigation times. Such data will allow the system to be adequately sized for the particular application.

Level of Involvement

Drip irrigation systems are implemented at the household and agro-company levels.

Costs

No cost data were available. However, because these systems generally use readily available PVC and polyethylene piping systems, they are generally cost competitive with traditional spray irrigation systems based on steel or aluminium piping. Notwithstanding, there is a moderate to high capital cost associated with the application of this technology.

Effectiveness of the Technology This technology is highly water-efficient, resulting in fewer transmission losses than traditional irrigation techniques.

Suitability

The drip irrigation method is suitable for cultivation of edible (grapes, fruits, and vegetables) and ornamental (nursery stock) plants with high commercial value. This system may be used not only to increase soil moisture but to apply fertilizers and micronutrients as well.

Advantages

This technology improves the growth rates of high value crops by delivering moisture directly to their root zones. This saves water because only the important part of the plants are irrigated. Weed growth is reduced since only the plant is irrigated, and working between the plants is easier because of the dry soil. This technology can be used in hilly terrain, and is not labour-intensive as it can be automated. The technology can be adapted to use energy-saving components.

Disadvantages

The technology is not well suited to machine-based cultivation, as the machinery may damage the pipelines. If not properly applied or monitored, these systems can increase the salt concentration of certain soils and result in over-irrigation. The capital costs of the equipment needed to employ this technology may be higher than those for surface or sprinkler irrigation systems. Drip irrigation also suffers from the tendency for the drippers to become stopped up easily.

Cultural Acceptability

The method is fully compatible with traditional methods of irrigation used in southern parts of Europe.

Further Development of the Technology

The technology is one of the simplest irrigation methods and fully developed.

The NETAFIM® Drip Irrigation System

The NETAFIM drip irrigation system is an example of one type of irrigation technology, developed in Israel and being used in Hungary, which employs pressure-compensated dripperlines equipped with a proprietary pressure differential mechanism. The dripper maintains a constant discharge rate over head pressures ranging from 5 to 40 m, and lateral distances of up to 800 m. The system can accommodate a range of dripper spacings and discharge rates, and uses various wall thicknesses in the transmission lines to compensate for the wide range of operating pressures. The system can also be used with wastewater sources and has a high resistance to mechanical damage.

Unit costs of using this technology depend on the size of the irrigated area and type of equipment necessary. A 20 ha area using 32 640 m³/yr of water demand (= and application rate of 163 mm/yr), with filtering system, fertilizer injector, electric pump, pipeline system, dripper lines, buffer pond, and water supply well would incur a capital cost of about $48 000. The cost of operation and maintenance is also dependent on design factors. A 3 ha area for growing cucumbers, using water supplied from a well equipped with electric pumps, would incur costs of about $850/ha, although experience indicates that the unit operation and maintenance costs decrease as the irrigated areas increases. On a bigger irrigated farm the unit costs would be cheaper.

Information Sources

Petèr Kovac, Felsö - Tisza - Vidèki Környezetvèdelmi Felügyelösèg, 4400 Nyiregyhàza, Szèchenyi u.19, Hungary, Tel. (36-42) 310 155, fax: (36-42) 310 713.

Dr Kornèlia H. Kocsis, Felsö - Tisza - Vidèki Környezetvèdelmi Felügyelösèg, 4400 Nyiregyhàza, Szèchenyi u.19, Hungary, Tel. (36-42) 310 155, fax: (36-42) 310 713.

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