Understanding Crop Growing Pattern in Bardhaman district of West Bengal using Multi-Date RISAT 1 MRS data
Information on crop phenology is essential for evaluating crop productivity and crop management. Phenological phases of rice and jute show great inter-annual variability and also large spatial distribution in West Bengal. Hence, it is essential to map the pheonological patterns. In this study spatio-temporal monitoring of the growing pattern of rice and other crops was carried out using multi-date RISAT-1 MRS data in the major rice growing region of Bardhaman district of West Bengal. RISAT-1 provides C band (5.3 Ghz) SAR data. The MRS (Medium Resolution ScanSAR) mode data with HH polarization having spatial resolution of 25 m and swath 115 km was used for this study. Total fifteen sets of MRS SAR data (with repetivity of 25 days) covering a complete year (May, 2013 to April, 2014) was used. Pre-processing of multi-date MRS data included georeferencing, calibration, image-image registration and speckle removal using Lee filter. Groundtruth collected during various cropping seasons (pre-Kharif, Kharif and Rabi) were used to generate crop signature pattern based on which hierarchical decision based models could be formed for classification. The periodic backscatter pattern of different crops and crop sequences were analysed. Accuracy of rice crop classification was higher by using 4-date data, compared to 3-date data. Rice transplanting patterns (Early, Normal and Late), both for Kharif and Rabi, could be identified using multi-date data. Major transplanting period for Kharif Rice was Early August and that of Rabi Rice was Early February.