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Cheng Xianjun, Engineer, Department of Irrigation and Drainage, Beijing, China |
SUMMARY
As is true of many others, the Jingtaichuan pumping irrigation district reflects a high level of professionalism in terms of the design and construction of water conveyance facilities. However, the on-farm irrigation management is not so satisfactory. The beneficiaries, the farmers, are not satisfied with the irrigation service. The reason is that the system was designed and is operated in a top-down, centralized manner. It delivers water on a fixed rotational basis, with limited attention to the needs, skills and wishes of the farmers. By involving farmers in irrigation management and introducing an acceptable water-saving irrigation schedule, on-farm irrigation management and the irrigation service have been improved.
It is recognized that appropriate irrigation scheduling should lead to improvements in irrigation management performance, especially at farm level. Research has made available a large number of methods useful for irrigation scheduling, namely, analysis of crop water requirements, soil water reservoir, water stress indicators, and simulation models. Various water-saving irrigation scheduling methods are also available. However, the practical application of the findings and methods has been far below expectations. One reason is that in many irrigation systems, especially those in developing countries, the findings and methods are only used by researchers and engineers, but not farmers. It has been realized that the introduction, rather than the development, of appropriate irrigation technologies at farm level is a major bottleneck. However, no single model is universally applicable, because the local situation of any particular irrigation system is unique. This case study is based on the particular case of the Jingtaichuan pumping irrigation district, where technology transfer has been successful and where important benefits have been achieved in spite of the simplicity of technologies transferred.
BACKGROUND
The Jingtaichuan pumping irrigation district lies in the arid area of Gansu province, in the north-west part of China. The mean annual precipitation in this area is 184.7 mm, and the mean annual evaporation is 3 040 mm. Before the irrigation system was constructed, the reclaimable land and abundant solar energy and heat resources remained undeveloped due to the arid climate and scarcity of water resources. As Tengri Desert continued moving south, the natural condition further deteriorated. Residents in this area scattered into the mountains. Due to lack of water for irrigation, crop yields were very low, and the residents' standard of living was significantly below the poverty line.
Government agencies assert that the root cause of poverty in this area is the arid climate and scarcity of water resources. In order to help alleviate poverty, the government decided to lift water from the Yellow River to the high land along the river, reclaim and irrigate land and resettle residents out of the mountains.
TABLE 1 Irrigation schedule adopted in the Jingtaichuan pumping irrigation district
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Name of irrigation |
Irrigation time |
Irrigation quota (mm)1 |
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Winter irrigation |
8 Oct. - 15 Nov. |
187 |
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Spring irrigation |
Approx. 20 Mar. - 10 Apr. |
187 |
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1st summer irrigation |
25 Apr. - 18 May |
135 |
|
2nd summer irrigation |
19 May - 12 June |
150 |
|
3rd summer and 1st autumn irrigation |
13 June - 9 July |
127 |
|
2nd autumn irrigation |
Approx. 10 July - 31 July |
120 |
|
3rd autumn irrigation |
Approx. 1 Aug. - 20 Aug. |
120 |
1
Measured at the entrance of distributaries.
The irrigation project includes two stages of development. The first stage started in 1969 and was completed in 1975. The projected water discharge is 10.6 m3/s, to serve 20 000 ha of farmland. The second stage, which is studied in this paper, started in 1984 and was partially completed with the inauguration of irrigation in 1990. It was finally completed in 1994. The projected water discharge is 18 m3/s, to serve 33 333 ha of farmland. This project is a pumping irrigation project, with 13 pumping stations along the main canal lifting water from the Yellow River to the irrigation district. The average height of water lifting is 460 m and the maximum is 602 m. The water conveyance system consists of a 100-km main canal and 347 km of submain canals and subsidiaries. All canals in the system are lined with concrete boards. By 1994, the irrigated area in the irrigation district had reached 26 667 ha, and the output of grain production had reached 67 070 tons, which is 24 times that before the system was constructed. The project and its operation appear to have achieved notable economic, social and environmental benefits.
The irrigation system reflects a high level of professionalism in terms of the design and construction of the main water conveyance canals and other facilities. However, during the process of planning, design, construction and operation of the irrigation system, on-farm irrigation facilities and management practices have not been constructed and managed as well as the main and secondary canals and facilities.
The management agency for the irrigation system consists of five branches, with each being in charge of a fixed part of the irrigation area. Each branch is composed of several sections. During irrigation seasons, which are fixed periods of time every year, the irrigation agency lifts water from the Yellow River and delivers it to the five branches. Each branch delivers water to its sections and then each section distributes water to farmers according to the area of land they cultivate. The method of water delivery for the system is a combined one: rotational irrigation for distributaries and continuous irrigation for higher level canals.
The irrigation schedule widely adopted in the irrigation district is shown in Table 1, which shows two problems with the schedule:
· the irrigation duties are too high for efficient use of irrigation water, and
· the irrigation times are fixed, with little attention to crop water requirements.
The irrigation system was designed and is rated in a top-down, centralized manner, and it generally delivers water on a fixed rotational basis. Put another way, the system was designed and is operated by engineers for the convenience of engineers, with limited attention to the needs, skills and wishes of the presumed beneficiaries of the water, the farmers.
Due to some neglect of improvements for on-farm irrigation management, a series of problems arise:
· Irrigation water delivered per unit area is far above what is required; irrigation efficiency, especially field irrigation efficiency, is very low.· Low field irrigation efficiency means a waste of irrigation water, which leads to and aggravates the situation of water scarcity.
· Due to insufficient water resources for irrigation, the actual irrigation area is much smaller than the projected area. At present, the system can irrigate 27 000 ha of farmland, which is only 80% of the projected irrigation area.
INTRODUCTION OF WATER-SAVING IRRIGATION SCHEDULING TO FARMERS
The irrigation agency views water-saving irrigation as a priority and has long recognized the problem of wasting irrigation water. At first, experts and technicians from the agency analysed the reasons causing irrigation water wastage and found that inappropriate irrigation methods and flawed irrigation practices at farm level were the major reasons. They decided to construct demonstration projects to promote water-saving irrigation. Demonstration projects, including 'large diameter (400-500 mm), low pressure pipes for irrigation water conveyance' and other methods, have been tested, but the techniques have not been disseminated and irrigation water wastage is still a serious problem. Analysis has shown that the root cause of irrigation water wastage is low awareness among farmers about water-saving irrigation. Other reasons previously thought to be major are only superficial. Therefore, the management agency decided to start a new programme to popularize a water-saving irrigation schedule through involving farmers more in the process of water-saving irrigation scheduling.
The programme was first started in one branch of the system. The approach applied in this programme is a learning-by-doing approach, which consists of two elements: demonstration of the new water-saving irrigation schedule and training of farmers. The two elements are combined in the process of programme implementation.
In this programme, the demonstration was not the same as previous ones. It emphasized the involvement of farmers, not only experts and technicians, in the programme. Farmers are involved in the programme to work together with experts and technicians to discuss questions and make decisions at all stages of the programme.
The training of farmers was based around field activities with few classroom presentations. The field activities, organized on a village basis, were much appreciated by farmers and provided opportunities for lively discussion. The training of farmers was conducted in conjunction with the implementation of the demonstration.
It is important to involve farmers in the whole process of introducing water-saving irrigation schedules. To involve farmers effectively, they should be well organized. Committees at village level are established to take the organizational role. In most cases, the existing village council acts as the village irrigation committee.
The programme is still in progress, but some initial results have been obtained. The farmers, with the aid of experts and technicians, realized that:
· irrigation blocks are too large for the types of soil in the area, which are mainly sandy soils;· decreasing the irrigation interval may be beneficial to crops;
· reducing irrigation duties can conserve water and enable an increase in the number of irrigations.
After these initial changes were made, a second step in the programme was implemented: a search for ways to reduce irrigation duties and increase the number of irrigations. In this step, simple procedures are adopted: levelling fields and changing large checks to small ones. By so doing, the following results have been achieved:
· In the area conducting this programme, mean irrigation duties for summer irrigation have decreased to 120 mm (measured at the entrances of distributaries), a 30% decrease compared to the customary approach.· Water saved through reducing the irrigation duty can be used for irrigation when needed.
· The time (days) elapsed for every rotation of irrigation is reduced. This means that crop water requirements may be satisfied in a more timely manner.
· With the introduction of the new water-saving irrigation schedule, on-farm irrigation management and the irrigation service have improved.
Generally speaking, the problems related to the old scheduling have been overcome through the implementation of this programme. The direct impacts of the new scheduling can be summarized as follows:
· The efficiency of irrigation use of water has been improved. The irrigation duties are much smaller than the old ones, for example, the mean irrigation duties for summer irrigation have decreased to 120 mm (measured at the entrances of distributaries), a 30% decrease compared to the customary approach.· The flexibility has increased. By contrast with the fixed and longer period of time for every rotation of irrigation that elapsed under the old scheduling, it is more flexible and shorter under the new scheduling.
After these achievements, the irrigation management agency is now preparing to conduct the programme in a larger area of the irrigation district.
CONCLUSIONS
No complex or new technology was used in the programme to introduce a new water-saving irrigation schedule. What was used are only the simplest methods, which experts and engineers may think too simple to use. However, it is not so simple to introduce these technologies to farmers. To popularize the water-saving irrigation schedule and transfer irrigation techniques to farmers requires effective involvement of farmers in the whole process. Through this case study, we learned the following things:
· Farmer involvement in irrigation management is an important way for people to become aware of and select solutions to their own problems, and it contributed much to improving the irrigation service.· Farmer participation is very important for the implementation and success of water-saving irrigation scheduling. The success of any measure adopted to conserve irrigation water depends on it being understood and accepted by the beneficiaries, the farmers.
· The introduction, rather than the development, of appropriate techniques to promote the implementation of a water-saving irrigation schedule is of great importance. Sometimes, simple techniques accepted by farmers can lead to great benefits.
· In order to be effectively involved in the process of introducing a new water-saving irrigation schedule, farmers should be well organized. Existing local organizations, such as the village council, can serve to mobilize farmers to take organized action to enhance water conserving practices in irrigation and perform the organizational role.
