WATER RESOURCES SECTIONGLB CANAL MODERNIZATION: DEMAND SCHEDULING, FLOW MONITORING AND CONTROL

摘要

Irrigation project modernization is aprocess of technical and managerial upgrading (as opposed to mere rehabilitation) of irrigation schemes with the objective to improve resource utilization (labour, water, economics, environmental) and water delivery service to farms (Wolter and Burt, 1996). Irrigation projects must serve the farmer sufficiently well so that reasonably high on-farm production and on-farm irrigation efficiencies are attainable. To achieve good water delivery service at the farm level, engineers must first recognize that there are also qualities of service at every level in the project. An irrigation project is typically composed of a series of layers through which water passes. Each layer has an obligation to provide a good level of service to the next lower layer (Burt and Styles, 1999). For example, the main canal system must provide water with good service to the secondary canals; the secondary canals only exist to provide good service to the tertiary canals, and so on, down tothe ultimate user, the farmer. The key service components of water delivery are (1) equity, (2) reliability, and (3) flexibility. The flexibility subcomponents are (a) frequency, (b) flow rate, and (c) duration. In general, equity and reliability are pre-requisites for improved flexibility. Farmers must be confident that water will be supplied when and how it is promised as a pre-condition for their investing in improved on-farm irrigation technologies. In order to meet this promise, a project must also have mechanisms to meet this uhimate objective.