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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India,2002 
  
AN EMPIRICAL APPROACH TO RETRIEVE THE TRANSPLANTATION DATE OF 
RICE CROP USING RADARSAT SAR DATA 
Indrani Choudhury and M.Chakraborty 
Agricultural Resources Group 
Remote Sensing Applications Area 
Space Applications Centre 
Ahmedabad-380 015 
e- mail : Indrani Choudhury (icaug4 @yahoo.com) 
M.Chakraborty (manabsac @ yahoo.com) 
KEYWORDS: SAR (Synthetic aperture radar), model, transplantation, Scan SAR, HH-polarization, multi-temporal 
ABSTRACT: 
In this study, an empirical approach has been adopted to investigate biophysical parameter of rice crop using RADARSAT SAR 
data. Orissa (Baleswar and Bhadrak districts) and West Bengal (South 24 Paragana district) have been selected as the study area. 
RADARSAT ScanSAR Narrow B (SCNB) multidate dataset have been used as data source. The emphasis of this study is to 
understand the relationship of physical plant parameter obtained through field measurements and its interaction with microwave 
backscatter. The relationship has been inverted to predict the plant height. Using the ground information, predicted height is related 
to the days since transplantation. A model is coded in EASI-plus macro language of EASI/PACE software, which generates spatial 
transplanation date map of rice area. Validation of the model has been carried out using the ground truth data of Orissa of the year 
1999. For transplantation date retrieval, the RMS is found to be 5 and for height estimation, the RMS is found to be 1. In case of 
West Bengal and Orissa rainfall pattern for the kharif season was analysed and it has been found matching with the transplanation 
pattern of the area calculated by the model. The results are found encouraging and may lead to the operational application of the 
methodology for other rice growing areas. 
1. INTRODUCTION 
Monitoring of rice crop areas is one of the important activities 
of agriculture in India, where rice plays a central role in the 
food crop production system. An early monitoring system of 
rice areas provides necessary information on rice growing areas 
and on the rice growth conditions. 
SAR remote sensing has become a valuable tool in Kharif rice 
monitoring due to its unique capability for acquiring data 
almost independent of weather conditions and solar 
illumination. The multitemporal synthetic aperture radar (SAR) 
for rice crop monitoring have been demonstrated by a number 
of investigators (Hooge boon 1983, Ulaby 1978, Kurosu et al. 
1995, Premlatha and Rao 1994 and Patel 1995, M.Chakraborty 
and S. Panigrahy 1997 & 1999) etc. 
Apart from area and condition assessment, retrieval of different 
biophysical parameters viz. leaf area index, plant height, 
biomass etc. have been attempted relating these with SAR 
backscatter. A number of microwave backscattering models 
have developed (Bush and Ulaby 1976, Attema and Ulaby 
1978,Engheta and Elachi 1982, Brunfeldt and Ulaby 1984, 
Eom and Fung 1984, Allen et. al 1984, LeToan et al. 1984,Yun 
Shao 2002 etc). Specific physical plant parameter 
characteristics of vegetation are used as direct model inputs and 
the backscatter characteristics of various types of vegetation 
were predicted from these models. The results have generally 
been found encouraging. 
The operational utilization of SAR remote sensing data requires 
a better understanding of the physical interactions of 
microwaves with different plant parameters. 
Multitemporal data is more suitable for crop monitoring and 
condition assessment as changes and variations in crop growth 
can be observed and available information on crop growth and 
condition can be extracted. 
The main objective of the present paper is to retrieve the 
progress of transplantation pattern using RADARSAT SAR 
backscatter. Transplantation date of a particular area is 
considered to be an important input for rice crop condition 
assessment. Transplantation of rice crop depends on many 
factors viz. onset of monsoon, agricultural practice of the area, 
variety etc. All these factors give rise to a wide variation in crop 
calendar from one area to another area. Hence, a spatial 
transplantation date map as well as spatial crop calendar can be 
of great advantage to know such factors of a particular area. It 
also enables to identify the areas with delayed transplantation 
and we can therefore find out the reasons for delay. Late 
transplantation of particular area is mainly due to deficit of 
rainfall or due to submergence of the area by flood. 
« 
2. STUDY AREA 
Rice dominant areas like Orissa (Baleswar and Bhadrak 
districts) and West Bengal (South 24 Paragana district) have 
been selected as the study area. These sites have been selected 
since the area is mainly rainfed and varied-sowing patterns are 
observed. The rice crop grown in the kharif season has been 
addressed in the present study, which is having a wide 
transplantation calendar ex-panding from June end to August 
end. Transplantation of rice crop of the area varies with the 
rainfall pattern and weather conditions during the growth cycle 
of the crop. More than 60% transplantation was over by the last 
week of July and the rest were completed by the August end. 
The cultural practice adopted is dominantly rainfed shallow in 
case of Baleswar and Bhadrak districts and shallow,