| Author | Odhiambo Lameck Odeck |
| Call Number | AIT Diss. no.IR-94-01 |
| Subject(s) | Water balance (Hydrology)
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| Note | A dissertation submitted in partial fulfillment of the requirement of the degree of Doctor of Technical science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. IR-94-01 |
| Abstract | The various types of field layout in lowland paddy fields influence the field water balance in different ways leading to different design requirements for different land, hydrological conditions, and water management practices. The aim in this study is threefold; first, to develop a water balance simulation model applicatiable to lowland paddy fields; second to analyze the influence of different types of paddy field layout design on the field water balance condition under different land,hydrological conditions, and water management practices; and thirdly to develop producers for selecting the optimal types of field layout and water management practices when improvment of the field water balance condition is the prime objective. In the first case a water balance simulation model was developed and validated using data collected from controlled plot experiments conducted at the Asian Institute of Technology experimental farm. The model is organized into a main program and five independent modules for simulating specific hidrologic and/ or hydrologic processes in the water balance system. In the second case, the model was applied to analyze the water balance components in a large irrigated area and to dianose the shortcomings in the existing layout structure and water management practices. In the third case, simulation experiments were conducted using the model developed to investigate the influence of idealized field layouts on the water balance condition under different land and hydrological conditions and water management. The results of model application to a large irrigated area show that water loss from the field was mainly by surface runoff (over 50%) due to a combination of field physical conditions, water management and layout factors. Poorly maintained paddy bunds and lack of adequate on-farm water control structures appeared to have a more significant influence. Seepage and percolation losses, contributed less than 15% of the loss. The overall results of the numerical experiments indicate that significant improvment in the performance of plot-to-plot irrigation systems can be achieve by appropriate sizing of stream size, bund heights, spillway size, block size, and number or plots and order of plot arrangement by size. By using the developed water balance-field layout model, appropriate irrigation stream size, bund heights and spillway dimensions can be selected for any field condition. A method of evaluation consisting of an index and scale was introduced to measure the extent to which different layouts impacts either positively or negatively on the field water balance conditions. These were interpreted in the light of results from the simulation experiments and use to develop a criteria for selecting optimal field layout for various categories of land conditions, rainfall, and available irrigation supply. Use of the evaluation indicators and scale facilitated making dicisions about which layout best meets the various water balance objectives. Hence it provided a procedure by which different types of layout could be evaluated for selection, comparison or improvement |
| Year | 1994 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. IR-94-01 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Irrigation Engineering and Management (IR) |
| Chairperson(s) | Murty, V. V.N; |
| Examination Committee(s) | Kono, Y;Murali, N. S;Mizutani, M.; |
| Scholarship Donor(s) | Japan International Co-oparetion Agency (JICA); |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology |