| Author | Natapon Apinontano |
| Call Number | AIT Thesis no.WM-06-9 |
| Subject(s) | Rain and rainfall--Thailand, Northern--Forecasting
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| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | This thesis addresses rainfall radar measurement and rainfall forecasting using radar data in Chiang Mai and Chiang Rai provinces. Radar rainfall measurements suffer from various types of errors and uncertainties, which necessitate strategies that can correct or reduce the extent of the error present. Estimation of rainfall from radar measurements consists of two methods. These are: 1) traditional matching method (TMM), 2) window correlation matching method (WCMM). Three set of radar images and 12 rain gauges data from 9 September 2006 to 12 September 2006 have been used in order to calibrate the Reflectivity(Z)-Rainfall(R) relationship. The result obtained from the TMM provides poor estimation of radar rainfall because geometrical mismatch and timing errors. WCMM has been successfully used to correct collocation and timing errors in Z-R pair matching to reduce Z-R conversion error in radar measured rainfall. The calibration of Z-R relationships using WCMM shows fairly satisfactory the values of coefficients are 0.665 (S55TO) at Chiang Mai with 120 km radar radius, while Chiang Mai at 240 km radar radius shows 0.564 (S55T10) and Chiang Rai at 240 km radar radius, 0.492 (S33T20) shows the best result. In this thesis, a translation model that uses radar images to forecast rainfall is presented. Input data for model are successive radar image of rainfall events. The Translation model is developed to predict radar reflectivity with lead time 1 hr. To evaluate the model, a comparison is made against radar data measured from the three radar sites, Chiang Mai at 120 km., Chiang Mai at 240 km. and Chiang Rai at 240 km, have taken the Critical Success Index (CSI) as measure of forecast skill. The CSI can be used to score techniques that make categorical forecasts of exceedance of a specified threshold of rainrate or rainfall accumulation. Total 82 rainfall events contain 447 radar images has been used as input of the model. The results show that model is applicable for 1 hour forecast with CSI varies from around 40 up to 90%. |
| Year | 2007 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Clemente, Roberto S;Sutat Weesakul; |
| Examination Committee(s) | Gupta, Ashim Das;Babel, Mukand Singh; |
| Scholarship Donor(s) | Ministry of Agriculture and Cooperatives (MOAC), Thailand;AIT Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2007 |