MAIN CANAL OPERATION MODEL -A CASE STUDY

Abstract

In many irrigation systems, water is managed. by gra-vity conveyance system, Only a few do so reliably to optimise water use efficiency. A variety of socio-economic, institu- tional, physical and technical objectives limit the performance of such projects. One component that suffers from these con-flicts. is the main canal operation. In main canal operation, the operation schedule of the distributaries, which determines the inflow into the main canal, is required to be specified, Operating all the distri- butaries simultaneously would recessiate larger main canal capacity, while total running time of the main canal might exceed the time available for that part of the rotation if the distributaries are run in sequence. Hence distributaries are required to be rotated which also helps the irrigation staff to organise their time and enable, them to supervise larger area. It also facilitates periodical maintenance. Large varia-tion, in the required daily discharge of main canal increases the operations of head regulator and controlling measures, increases the operational losses, hampers the equitable distri-bution, and results into wastage of water through escapes. Hence the need for a carefully drawn operation programme which would supply water to all distributaries within the time avai-lable for rotation., and that would require daily discharge into the main canal as constant as possible, assumes special significance. (iv) In this dissertation, an attempt has been made to review the main canal operation practices that are in vogue, and a model for operation of a main canal is proposed and implemented, Integer optimisation technique and a hueristic, proposed, aim at achieving objective mentioned above. The heuristic procedure appears to be computationally efficient and easily adaptable. The economic evaluation of procedures followed in allocation of available water to different distributaries under scarcity and surplus conditions of water availability has brought out certain observations. There appears to be scope for improvements. A proportional allocation rule, (in which a set of fractions is determined each of which represents the fraction of available water that is to be diverted to each distributary), that results in greater average net benefits, is suggested. This model can serve independantly or can be used as submodel for conjunctive use management for planning ground water allocation at different levels of water availa-bility.