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Multiple objective decision making in irrigation management | |
Author | Kalu, Indra Lal |
Call Number | AIT Diss. no. WA-91-07 |
Subject(s) | Irrigation--Management |
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-91-07 |
Abstract | This study has two main aspects. First, an existing irrigation system is studied extensively to analyze water management problems. Secondly, comprehensive mathematical models including multi-objective decision making are developed and applied to improve water management as well as to develop the on-farm system. Information obtained about the system from the field studies, household survey and other sources were analyzed to evaluate the present water management situation, existing agricultural situation and cropping pattern and to identify the needs of improvement in the system. It is found from the socio-economic survey that sizable proportion of farmers are receiving no or inadequate irrigation causing inequitable water distribution, especially during dry season for the limited water supply. Water distribution inequity was more among fields within a canal reach, than that among various canal reaches. This is found to be caused due to the lack of an adequate on-farm channel system. Two objectives - equity and net benefit were given importance by the leader farmers during water distribution among the fields. The reform in the operation policy and the construction of on-farm distribution networks were the major demands in that system. To analyze these problems in a systematic manner, three models: two related to the operational policy considering the crop planning and the water distribution planning; and one related to identifying the cost effective structur~· improvement were formulated for the system. Three objectives - food production, net benefit and crop· area maximization were considered in formulating the crop planning model, which was solved in the multiple objective framework by employing both compromise programming and the constraint method. Comparison of results from multiple objective analysis was made with the results from single objective optimization models. And the sensitivity analysis on the available resources used in the application of model was performed. The spatial water distribution planning model dealt with the selection of a policy for allocating water to individual field plots in the system taking into consideration both efficiency and equity objectives. Controversial issues about equity and efficiency are often raised in literature, in this study a model is formulated to analyze the issue systematically by generating different possible policies. Simulation model comprising of the soil water -11- balance and the actual evapotranspiration estimation submodels were employed to derive irrigation demand for each plot to use in the optimization models for delivering water during each irrigation interval. At the end of a crop season, various measures of efficiency and equity were evaluated and the compromise solutions were determined considering different sets of multiple objectives and parameters of compromise programming for each water distribution policy. Results shows that compromise solutions can be formulated to reduce conflicts to an extent. Analysis of different possible means of reducing water shortage problem such as improving irrigation efficiency and augmenting water supply are made in a single model. A mixed-integer programming model was formulated to determine an optimal cropping pattern and the extent of structural improvement required at farm level. Equivalent annual costs of four possible options considered namely the precision land leveling, channel improvement, shallow tubewell drilling, and the farm service reservoir construction were compiled and the benefits that can be derived from each option were evaluated in terms of the quantity of water that can be supplemented on a seasonal basis. The model was applied to an outlet command of the system for illustration. Application of the described approach provided an insight to the different aspects of management, including the causes for poor performance of the system. The main cause of the problem in this study is found to be the lack of adequate channel networks, which has also created other problems e.g. inequitable water distribution and social conflicts among farmers. Other problems are the lack of adequate water supply and the proper operation planning. Possibility of improving various objectives are elaborated in the multiobjective operation planning model. But the actual performance can be upgraded by increasing the water supply with shallow tubewells. The cost effectiveness of optimal on-farm development works differed with the change in interest rate and the crop price. |
Year | 1991 |
Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WA-91-07 |
Type | Dissertation |
School | School of Engineering and Technology |
Department | Other Field of Studies (No Department) |
Academic Program/FoS | Water Resources Research Engineering (WA) |
Chairperson(s) | Gupta, Ashim Das ;Paudyal, Guna N. ; |
Examination Committee(s) | Harboe, Ricardo ;Weber, Karl E. ;Loof, Rainer ;Doppler, Werner ; |
Scholarship Donor(s) | The Government of Japan ; |
Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1991 |