Spatial rainfall distribution and its impact on the water demand of a large irrigation system | |
| Author | Phattaporn Mekpruksawong |
| Call Number | AIT Thesis no. WA-92-17 |
| Subject(s) | Rain and rainfall Irrigation water Crops and water |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. WA-92-17 |
| Abstract | Large irrigation command areas are often handicapped by inadequate rainfall measurement systems. Though rainfall is very much an integral part of the demand estimation, negligence of its importance results in poor irrigation planning and management. It is necessary to determine the rainfall distribution pattern over the command area of an irrigation system in order to incorporate the rainfall component accurately in the demand model. This study uses geostatistical method for the estimation of spatial rainfall distribution and attempts to identify its effects on the planning and management of the Phitsanulok Irrigation Project in Thailand. The results of areal precipitation are compared with the estimations from the traditional methods based on deterministic approaches (viz. the arithmetic method, the thiessen polygon method and the isohyetal method). The results indicated that geostatistical method gives the most accurate results. Considering geostatistical method as the base, comparison of project irrigation water requirements is made with the values adopted by some planning level and management level studies, which used the traditional (arithmetic) method for estimating areal precipitation. It is found out that at the planning (monthly) level, the computed irrigation water requirements by all the previous planning studies are underestimated by about 12 to 23 %. At management (weekly) level, the computed irrigation water requirements are 0.4 % less than the project estimate and 4.7 % less than the estimate made using observed rainfall data at the representative station inside each sub-project area. However, the project currently seems to have overestimated in-igation water requirements by about 16.5 % in Dong Setthi sub-project (middle reach) and underestimated by about 12.3 % in Thabua sub-project (tail reach). Hence, the calculation of inigation water requirements by personal irrigation project can be improved by using the geostatistical method for areal precipitation estimation. |
| Year | 1992 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. WA-92-17 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Water Resources Research Engineering (WA) |
| Chairperson(s) | Loof, Rainer ; |
| Examination Committee(s) | Onta, Pushpa Raj ;Nophadol In-na ; |
| Scholarship Donor(s) | The Government of Japan ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1992 |