Analysis of spot vegetation NDVI for mapping irrigated and non-irrigated rice cultivation | |
| Author | Daroonwan Kamthonkiat |
| Call Number | AIT Diss. no.RS-05-1 |
| Subject(s) | Rice--Irrigation Vegetation mapping |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Technical Science |
| Publisher | Asian Institute of Technology |
| Abstract | This study describes a technique named "Peak Detector Algorithm (PDA)" for discriminating the rainfed and irrigated rice cultivation areas in Suphanburi province, Thailand. The ·methodology uses three year time series data of SPOT VEGETATION S 10 NDVI (10 day composites) to identify cropping intensity (number, timing and peak values). Peak NDVI is lag-correlated with long term average rainfall data. There is a high correlation at a 40-50 day lag, between a peak rainfall and a 'single' peak NDVI of rainfed rice. In irrigated areas, there are multiple peaks, and multiple correlations with low values for at least 90 days after peak rainfall. The methodology currently uses a mask to remove un-cropped and non-rice areas, which is derived from existing GIS data. The method is successfully discriminate between rainfed and irrigated rice crops in Suphanburi with a classification accuracy of 90% against a reference map (the combination of land use - only rice crop and irrigation maps) and independent ground truth data. The procedure is evaluated in other provinces in different climate zones of Thailand, Khon Kaen (North-eastern), Phatthalung (Southern) and Chiang Mai (Northern). The achieved classification accuracies are 83%, 58% and 75% respectively against independent ground truth data. The method showed less accuracy in identifying irrigated and non-irrigated rice in Phatthalung where a long rainy season lingers 8-9 months and high amount of rainfall in a year induces farmer to grow two crops in non-irrigated area. The fixed cultivation period of photosensitive rice called "Leb Nok", grown in many areas both in and out side irrigation zone as high consumption local rice, makes difficult to categorize NDVI fluctuation patterns (time lag between the peak of NDVI and the peak of rainfall) of irrigated and non-irrigated rice. PDA was developed for detailed classification of rice cultivation in Suphanburi province based on cropping intensity that includes 5 classes, Non-irrigated, Poorly irrigated - 1 crop/year, Irrigated - 2 crops/year, Irrigated 3 crops/year and Others. The overall accuracy of all classified results (1999-2001) is around 77% against independent ground truth data. High accuracy of this methodology shows considerable promise for using it for the applications at provincial/regional scale to discriminate irrigated and rainfed crops as well as cropping intensity. It is designed as a second level of analysis to refine classifications using other techniques of mapping irrigated area at regional and global scale. |
| Year | 2005 |
| Type | Dissertation |
| School | School of Advanced Technologies (SAT) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Remote Sensing (RS) |
| Chairperson(s) | Honda, Kiyoshi; |
| Examination Committee(s) | Tunal (IWMI), Hugh;Tripathi, Nitin K;Vilas Wuvongse;Yasuoka, Yoshifumi; |
| Scholarship Donor(s) | Royal Thai Government; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2005 |