Rabi cropped area forecasting of parts of Banaskatha District,Gujarat using MRS RISAT-1 SAR data
Other literature type
Parekh, R. A.
Mehta, R. L.
(issn: 2194-9034, eissn: 2194-9034)
Radar sensors can be used for large-scale vegetation mapping and monitoring using backscatter coefficients in different polarisations
and wavelength bands. Due to cloud and haze interference, optical images are not always available at all phonological stages
important for crop discrimination. Moreover, in cloud prone areas, exclusively SAR approach would provide operational solution.
This paper presents the results of classifying the cropped and non cropped areas using multi-temporal SAR images. Dual polarised
C- band RISAT MRS (Medium Resolution ScanSAR mode) data were acquired on 9<sup>th</sup>Dec. 2012, 28<sup>th</sup>Jan. 2013 and 22<sup>nd</sup> Feb. 2013 at
18m spatial resolution. Intensity images of two polarisations (HH, HV) were extracted and converted into backscattering coefficient
images. Cross polarisation ratio (CPR) images and Radar fractional vegetation density index (RFDI) were created from the temporal
data and integrated with the multi-temporal images. Signatures of cropped and un-cropped areas were used for maximum likelihood
supervised classification. Separability in cropped and umcropped classes using different polarisation combinations and classification
accuracy analysis was carried out. FCC (False Color Composite) prepared using best three SAR polarisations in the data set was
compared with LISS-III (Linear Imaging Self-Scanning System-III) image. The acreage under rabi crops was estimated. The
methodology developed was for rabi cropped area, due to availability of SAR data of rabi season. Though, the approach is more
relevant for acreage estimation of kharif crops when frequent cloud cover condition prevails during monsoon season and optical
sensors fail to deliver good quality images.