IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India, 2002
interpretation of the data leading to the delineation of the post
kharif rice fallow fields. Image processing software
EASI/PACE 6.3 version was used to carry out this analysis.
Prior to defining the training areas, a separate Normalised
Difference Vegetation Index (NDVI) was computed, using the
reflectance data of red and near infrared bands in digital
numbers. This NDVI was used as an additional dimension to
the red and near infrared channels in the classification.
Based on the ground truth information and a priori knowledge,
training areas were defined on the satellite data corresponding
to the kharif season and signatures were generated. The
signatures were checked for their separability through
bivariate spectral plots. The spectral signatures of different
agricultural land covers were distinct and separable and resulted
in obtaining better classification accuracies. This was followed
by classification of the satellite data, employing the maximum
likelihood algorithm (Schowengerdt, 1997). Similarly, the post
kharif data was also classified and the crop covers and the
fallow lands were delineated. These two outputs viz., kharif rice
cropped areas and the fallow lands were unioned to obtain the
spatial distribution of the fallow lands, with rice crop in the
kharif season and the area statistics were also generated.
4.6 Post classification verification / validation
The classified outputs of kharif 1999 showing the cropped areas
and the rice-fallows of rabi 2000 of Bangladesh were verified
using the field information available with liaison offices of
- ICRISAT in Bangladesh. The feedback enabled to properly
label them into different crop classes. The numerical estimates
of kharif rice acreage estimates using RADARSAT data and of
wheat acreage using WiFS data in the national level rice and
wheat production estimation projects under FASAL project of
the Department of Space were also used in verifying the
classification results for the estimation of kharif rice and the
wheat acreage in the following rabi season.
5. RESULTS & DISCUSSION
The satellite derived acreages of kharif rice and rabi fallows
obtained in the present study are presented in the table 1. A
perusal of the table indicates that in India kharif rice and rice
fallows covered 40.2 and 11.65 M ha respectively. In Pakistan,
kharif rice covered 2.45 M ha and the post kharif rice fallows
occupied 0.14 M ha. In Bangladesh kharif rice covered 6.36 M
ha and rice fallows occupied 2.11 M ha. In Nepal, most of the
kharif rice crop of 1.45 M ha was concentrated in the Southern
Terai districts, where wheat is the dominant crop in the rabi
season thus leaving only 0.39 M ha of rice fallow lands.
In order to evaluate the intrastate classification accuracies, three
categories of districts were identified in each State, representing
high, medium and low coverage of kharif rice and rabi wheat
crops. Two districts were selected from each of these
categories. The estimates obtained using the selected WiFS
datasets in this project for these districts were compared with
government estimates of recent past or of normal acreages and
district wise estimates of other studies using remote sensing
techniques.
The estimates of the kharif rice at State level were evaluated
using the WiFS data of the present study with the Radarsat data
of FASAL project. The relative difference at individual State
level ranged from 0.90 to 11.2896, with an overall relative
difference of 2.3596, indicating a close agreement. The wheat
acreage estimates at State level using the WiFS data of the
present study were compared with those generated by the multi
date WiFS data, employing the sampling approach. The
relative difference at individual State level ranged from 0.44 to
7.8196, with an overall difference of 3.83 96. This indicated
overall differences between the estimates made in this project
vis-à-vis the FASAL project were low validating the
methodology adopted in this study.
5.1 INDIA
India is the second largest producer of rice in the world, next to
China with well developed irrigation infrastructure and
adoption of improved practices. In India, rice is mostly
cultivated during kharif season, coinciding with the period of
active monsoon rains. Rice is distributed almost in the entire
country, with the highest concentration in the Eastern and the
Southern bound States. Availability of irrigation waters
expanded the cultivation of rice crop to the sandy soils of the
north Indian States of Punjab and Haryana also. Sugarcane,
cotton, chillies and tobacco are the other important cash crops
grown in kharif season.
In the northern part of India, wheat, mustard and gram are the
major rabi crops because of the congenial pedo - climatic
conditions. In South India, rice-rice and rice-pulse cropping
systems are predominant, depending upon the availability of
irrigation facilities. India is the largest pulse producing nation
and accounting nearly 1/5th of the total area under food grain
crops and contribute about 1/12th of the total food grain
production in the country (Jagdish Kumar, 2000).
State-wise distribution of kharif rice and post kharif rice
fallows was grouped into five regions based on the agro-
ecological perspective: (1) North India, covering Punjab,
Haryana, Uttar Pradesh and Uttaranchal, (2) Eastern India,
covering Bihar, Jharkhand, Assam, West Bengal and Orissa,
(3) Western India, covering Gujarat and Rajasthan, (4)
Central India, covering Madhya Pradesh, Chhatisgarh and
Maharashtra and (5) South India, covering Andhra Pradesh,
Tamil Nadu, Karnataka and Kerala States.
Tablel : Acreages of kharif rice and post kharif rice fallow
lands of Pakistan, Bangladesh, Nepal and India
Country Region/ Acreages (M ha)
State Kharif Rabi
rice fallows
Pakistan 2.45 0.14
Bangladesh 6.36 241
Nepal 1.50 0.39
India Western India
Rajasthan 0.21 0.02
Gujarat 0.47 0.08
North India
Punjab 2.5 0.00
Haryana 1.11 0.00
Uttar Pradesh 6.25 0.35
East India
Bihar 5.98 2.20
Assam 2.23 0.54
West Bengal 4.62 1.72
Orissa 3.88 1:22
Central India
Madhya Pradesh 5.60 4.39
Maharastra 1.77 0.63
South India
Andhra Pradesh 2.66 0.30
Karnataka 0.99 0.19
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