| Author | Das, Bitanjaya |
| Call Number | AIT Diss. no. WA-93-03 |
| Subject(s) | Irrigation--Mathematical models
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| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WA-93-03 |
| Abstract | Improving the operation and management of irrigation systems has been the focus of discussions for a considerable period of time due to their poor performance. Su bstan ti al research was undertaken regarding the on-farm development activities with the assumption that it can be a potential problem solving approach. However, the isolation of the conveyance systems from the on-farm management practices has been attributed to a greater extent responsible for the little success. Hydraulic modeling of the main canal of these systems is identified as a tool for improving the operational aspect which in turn can help in enhancing the overall performance of these systems. But lack of accomplishing optimal decisions regarding the releases to the canal reaches by a hydraulic model undermines the decision making on operational aspects. The integration of the optimization technique with this hydraulic simulation has been identified as an effective tool which can endorse an optimal operation. The concept of an embedded technique was employed in this study in order to develop an integrated model for the operation of the main canal. In this technique, the unsteady flow simulation model is embedded into an optimization model thereby acting as an important constraint. The unsteady flow simulation model provides feedback on the state of the system resulting on a decision and the subsequent decisions are taken by the optimization model as per the prevailing state and the day-to-day demand of the command area. Dynamic programming was chosen for the optimization considering the objective function of minimizing the quadratic deviation between the desired and actual water levels. The nonlinearity in the objective function, constraint along with the sequential nature of decision making involved in operating the system confirms the application of dynamic programming. The objective of maintaining the optimal water level as close as possible to the full supply level (FSL) was conceived as a considerable improvement in the operation. The application of the model to the operation of the main canal in the Phitsanulok Irrigation Project approved the usefulness of the new concept. The unsteady flow simulation model along with the inclusion of the control structures were calibrated and verified successfully under field conditions. Employing the integrated model, optimal water levels were obtained very close to the FSL, thus satisfying the objective. Along with the optimal water levels, the model generated optimal releases required for satisfying the day-to-day demand. The model demonstrated that a substantial amount of water (26. 7%) for the whole dry season of 1992 could have been conserved by employing the operation suggested by this model. By comparing the observed operation of the main canal for the month of March, 1992 it was confirmed that, in the existing operation practices, the water levels were nowhere near the FSL whereas the supply was 35.4% higher in comparison with the optimized discharges. The development of the integrated optimization-simulation model can thus be attributed as a pure operational model. The model can in a long way help the operators of many similar irrigation systems in Asia and Africa for optimal operation and management by modifying the database. This will be a very cost effective software approach without any system's hardware modifications. |
| Year | 1993 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WA-93-03 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Resources Research Engineering (WA) |
| Chairperson(s) | Loaf, Rainer; |
| Examination Committee(s) | Paudyal, Guna Nidhi;Gupta, Ashim Das;Huynh Ngoc Phien;Eggers, Helmut; |
| Scholarship Donor(s) | Deutsche Gesellschaft fiir Technische Zumsammenarbeit (GTZ)GmbH, Germany; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1993 |