System-wide water management in publicly managed irrigation schemes in Vietnam

• National Institute for Agricultural Planning and Projection, Vietnam
• University of Agriculture and Forestry, Vietnam
• Vietnam Institute for Water Resources Research, Vietnam
• University of Technology, Ho Chi Minh City, Vietnam
• Southern Vietnam Institute for Water Resources Research, Vietnam

Vietnam's food supply is critically dependent on irrigated agriculture. About 80% of the 4 million hectares of cultivated paddy have some form of irrigation, although the area effectively irrigated is probably just over 2 million ha due to incomplete systems, planning and design inefficiencies, and poor operation and management.
With population growth, Vietnam's food requirements are expected to double by 2030. However, the current standard of operation, management and institutional arrangement for irrigation and drainage in Vietnam is inadequate to meet the challenge of such a large increase in food output.
Earlier ACIAR-funded focused on improving the technical capacity of the main irrigation system, and on establishing the institutional arrangements and legal framework needed to meet the changing socio-economic conditions. Scientists applied the IMSOP (Irrigation Main System Operation) model to the La Khe irrigation system in the Red River Delta. This project transferred and adapted project outcomes to suit the Dan Hoai irrigation scheme (also in the Red River Delta) and to the Cu Chi irrigation scheme in the Saigon River system.

The ultimate objective was to improve the efficiency of operation and the sustainability of Vietnam's publicly-managed irrigation systems, and to develop and implement a comprehensive system of performance evaluation.

The project comprised three subprojects which were carried out at three irrigation schemes: two were pump operated schemes located in Ha Tay Province - Dan Hoai and La Khe; the third was the Cu Chi scheme, a gravity-fed scheme located in southern Vietnam. In the first subproject the team extended the findings from the earlier project to the new areas in southern Vietnam, including reservoir-supplied systems.
In the second subproject the team examined and evaluated the performance of irrigation in rice-growing systems to determine the impact of the proposed new water management improvements. This also provided a framework that could be applied to irrigation systems elsewhere.
The third subproject developed new methods to monitor crop pattern development, using Synthetic Aperture Radar remote sensing. This technology is designed to overcome limitations in the accuracy and timeliness of existing data collection methods.

This project focused on the investigation of engineering, agricultural, institutional and economic aspects of improving irrigation management in publicly managed irrigation schemes in Vietnam. It comprised three subprojects which were carried out at three irrigation schemes: two pump-operated schemes located in Ha Tay Province: Dan Hoai and La Khe; and the other, the Cu Chi scheme a gravity-fed scheme located in Southern Vietnam. The project aimed to improve the standard of operation and management of the three irrigation systems by improving their technical capacity to manage water distribution and by introducing new institutional arrangements. It built upon the improvements of the technical capacity of the Le Khe irrigation company and associated new institutional arrangement tested in an earlier project (LWR1/1994/004). The project also developed a system of performance evaluations in terms of resource use, operation, infrastructure use, and finances. Performance evaluation aimed to allow measurement of changes in response to the improved water distribution and institutional arrangements introduced by the project. New areas of research in the project included means of improving infrastructure survey methods and new methods for crop identification and area estimation. The latter were derived from data collected in Australia and the Philippines using airborne synthetic aparture radar.

The project completed the development and application of the Irrigation Main System Operation model (IMSOP) in all three irrigation systems (available in English and Vietnamese). The process involved implementation of the IMSOP model to simulate the operation, retrospective analysis of the system, monitoring existing operation and field trial of alternate operational scenarios.

Project scientists designed and developed a GIS based Asset Management Framework and Software which can be used to manage infrastructure in any irrigation scheme. The software tool can be used to maintain an up-to-date database of asset condition and carry out various financial calculations and modelling including depreciation and condition based renewal costs.

A seven-step development process leading to the formation of a Water User Association under the Cooperative Law in secondary canal N5 in the La Khe irrigation system was completed and trialled for 2 years. The Water Users Association model had provided benefits to farmers although it is still largely viewed by local authorities as an advisory body. A WUA charter, internal regulations and constitution were developed. Whilst the model was shown to function well as a locally managed irrigation and drainage organisation, the future extension of this model to other systems is closely linked to the ability of the Vietnamese authorities to speed up reforms in the irrigation sector.

The main effort in Subproject II was directed to the evaluation of water productivity in Cu Chi and economic analysis to evaluate the water management changes. Water balance measurements were carried out in the experimental area for the main crops in 2001 and 2002 and Winter-Spring crop in 2002. The analysis of water balance showed very low water productivity of rice in Cu Chi in both the years (0.6 kg/m3). During the Winter-Spring season farmers cultivated peanuts and corn in addition to rice. Farmers' income from rice was estimated at A$400 per ha, whereas combined crop of rice, corn and peanut would give a higher income (A$860 to A$970).

The economic component of the study focused on the assessment of farmers' profitability, the impact of available water supply on rice yields, returns from agriculture and household income. The study of gross margin in the three systems concluded that a wide diversity exists between systems and within them. Variability in the availability of water within the system appears to have little effect on the yields and incomes of farmers in La Khe. In Dan Hoai there is some evidence that Winter-Spring rice yields are lower for farms located at the end of the irrigation system. In Cu Chi, yields for all rice crops were lower for farms at the end of the system, and net returns per hectare from cropping activities highest at the top of the system. It should be remembered however that many factors other than water availability affect crop yields and this study does not account for other possible factors influencing yield variability.

The process of implementing volumetric prices in Vietnam is difficult, due to institutional immaturity, and the nature of the irrigation infrastructure in Vietnam. The project proposed that water should be charged according to a two-tier formula based on the water user associations buying water on a volumetric basis from the irrigation management company and charging farmers on an area basis. Such an approach will provide incentives for water users associations to buy as little water as possible and for farmers to ensure that the water is distributed as equitably as possible within the WUA.