Performance measure for improving irrigation management

A measure to evaluate performance in irrigation systems is analyzed using the mean square prediction error concept. In the context of irrigation system management, the term error means the deviation of actual performance from a reference performance. The measure assesses performance in terms of the management objectives of adequacy and dependability of water delivery and an equitable distribution among various water users. It provides an understanding of the management capacity to schedule and distribute water in an irrigation system. Application of the performance measure is demonstrated by evaluating performance of an irrigation system in the Northwest Frontier Province of Pakistan.     

Irrigation Policy Reforms for Rice Cultivation in Egypt

This paper reports a fieldresearch that evaluated irrigation waterdelivery options for promoting conservativewater use in rice cultivation. Ricecultivation in the Delta region of Egypthas grown dramatically, replacing cotton asthe major summer crop. The Ministry ofWater Resources and Irrigation is findingit difficult to limit the area planted torice since rice cultivation is profitableto farmers. A socially more feasibleoption is to encourage farmers to cultivateshort-season rice varieties. The Ministrycan then adopt the policy that will provideirrigation water to the farmers to supportcultivation of 120-day rice varietiesrather than 160-day traditional varieties. The field studies conducted for two yearsin the Nile Delta conclusively show thatthis is indeed feasible. Farmers in thedemonstration canal areas were able tosuccessfully finish 120-day ricecultivation, which allowed the Ministrystaff to end the rice water delivery about35 days early and realize substantial watersavings.     

Modelling water control needs for diversified cropping

The background and concepts of water control for crop diversification in rice-based irrigation systems are discussed. Water control is described in terms of the irrigation event volumes and intervals between irrigation events. The development of the WACCROD model to simulate these water control parameters under selected agroclimatic conditions is described. The simulation model can recommend irrigation event volumes and intervals for various dry season cropping patterns in rice-based irrigation systems. Also, the application of the model to a general situation at field level of a ‘typical’ rice based irrigation system is reported.     

Irrigation system design for management in mountainous areas

The paper reports research on engineering designs of irrigation systems in mountainous areas and the resulting implications for management. The engineering designs are important because they may or may not provide the social basis for local people to participate in system development and management. This hypothesis is analyzed by using field data from an irrigation development program in the Himachal Pradesh State in India. The development program will construct about 150 small-scale, gravity flow and lift irrigation schemes in a seven year period. The results of the analysis support the argument that the engineering designs critically influence local people's capability and willingness to manage irrigation facilities. In gravity flow irrigation schemes, water capture by permanent flow diversion structuress is extremely expensive and yet unreliable because of large variation in stream flow and unstable mountain slopes. A more practical alternative is to utilize diversion structures of temporary nature which are made with local materials. Construction and management of such structures will encourage local participation because of high maintenance requirements. In lift irrigation schemes a conventional design is to lift all water requirements to a single highest point in the command area. This practice results in unnecessarily high energy costs and in a water distribution system which is complex to manage. A better alternative is to design the pumps so that water can be delivered at variable elevations in the scheme area. This will allow disaggregation of the total area into smaller rotational units and, therefore, management of water distribution can be potentially easier and equitable.     

Irrigation water management for crop diversification: Application of the WACCROD model

The actual water management practices, in terms of the volumes and intervals of delivery, are examined in a rice-based irrigation subsystem where crop diversification is practised. A simulation model (WACCROD) is used to generate the hypothetical water requirements of the changing crop mixture at quartenary and tertiary levels.Crops other than rice were planted in the dry season to reduce the need for water. Then, as the available water supplies diminished, the volume and timing of water deliveries changed based on the time, hydraulic location and relative importance of the crop.