IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India,2002 
  
  
    
  
  
   
   
  
    
     
  
    
   
     
    
   
  
    
    
   
   
   
  
   
   
   
  
   
   
  
  
    
data obtained from India Meteorological Department (IMD) 
Weekly Weather Reports for the years 1977 onwards during 
November - March (rabi) period. Dadhwal (1989) and Saini and 
Dadhwal (1986) have highlighted the significant contribution of 
temperature on wheat yield in India. A trend was fitted to this 
yield series. Deviations from trend were regressed with 
fortnightly minimum and maximum average temperatures of 
rabi (Nov -Mar) season (Vyas et al. 1999). 
Early wheat yield forecast in February end/March beginning 
were obtained using truncated regression models, which used 
data upto Ist fortnight of February. The final pre-harvest wheat 
yields were based on the yield models developed using weather 
data upto February end. The yield equations were developed at 
meteorological sub-division level. The weighting factors, based 
on contribution of meteorological subdivision to state acreage, 
were used wherever necessary to arrive at the state yield 
forecasts. The final pre-harvest yield models and forecasts for 
2001-02 are given in Table 3. 
4. RESULTS 
4.1 ARIMA Analysis 
Historical national wheat production series for 1950-51 
onwards was taken from a publication of Directorate of 
Economics and Statistics. For the time series analysis, method 
developed and described by Box and Jenkins (1976), namely 
Auto-Regressive Integrated and Moving Average (ARIMA) 
analysis was followed. On the basis of analysis of auto- 
correlation and partial auto-correlation functions, ARIMA 
(1,1,0) was identified for wheat production series. Since this 
method does not use any in-season information/input/data, this 
formed an a-priori (or Fo) forecast at the beginning of crop 
season. The performance of this type of models for last six years 
(1995-96 to 2000-01) had deviations of 5.5496, -6.58%, 2.65%, 
—2.96%, —6.04% and 9.22%, respectively. 
Table 3 : Temperature based yield models and yield forecasts 
for 2001-02 using weather data upto March 
N,D,J,F,M stand for months from November to March; 
  
  
  
  
  
  
  
  
  
Met. MODEL , [YPRED_ YPRED 
STATE |. bdiv| PARAMETERS | |. M..|C 79]. s. |CYC9 
D2TN, D2TX, 
BIHAR| 9 |. orn | 9953 | 2200 | 72 2201 | 72 
HAR. | 13 D2TN 0.962 | 4307 | 487 | 4307 | 487 
PUN. | 14 | DITX,F2TN | 0972 | 464 | 46 | 464 | 46 
MP. | 19 | NITX;D2TN| 032 | 204 | 864 | 1854 | 7.65 
MP. | 20 | J2TX,FITN | 0.765 | 1.177 | 126 
JITX, F2TX 
RAJ. | 18 : '| 0957 | 2.265 | 10.92 | 2.265 | 10.92 
MITN, M2TX 
UP. 10 | N2TN,FITN | 0.938 | 2.488 | 841 | 2.804 | 5.15 
UP. 11 | N2TN,JITX | 095 | 3241 | 642 
  
  
  
  
  
  
  
  
  
  
1 and 2 are first and second fortnights respectively; 
TX: Maximum Temperature; 
TN: Minimum Temperature; 
CV is coefficient of variation in percentage; 
YPRED S is predicted yield for state; 
YPRED M is predicted yield for meteorological subdivision; 
Com. R? is combined coefficient of determination. 
4.2 Rabi- Cropped Area 
Since the early crop forecasts conflict with optimal bio-window 
for crop identification, the early assessment of total rabi sown 
area was incorporated. However, the existence of cropped area 
can be detected and mapped. Rabi crop area for the wheat study 
districts was attempted for the first time during 1997-98 season. 
If two or more cloud free data since mid-December were 
available, it was possible to detect large anomalies and give rabi 
cropped area using multi-date IRS WiFS data. 
4.3 Early And Final Wheat Production Forecast 
Early forecast of wheat production was planned to be made by 
end of February. The IRS WiFS data upto middle of Feb were 
used for wheat area estimation. The fortnightly minimum and 
maximum average temperatures upto Jan - end / Feb 15 at 
meteorological sub-divisions were used to develop truncated 
regression based yield models. The current year's temperature 
data were used to forecast the yields. 
The final national wheat production pre-harvest forecast was 
targeted to be given on March 31. The harvest of wheat starts 
around April 15 in Northwest India, which is major wheat 
production belt. The final pre-harvest forecasts used multi-date 
IRS WiFS data upto March 15 and weather data upto Feb end. 
The consolidated final forecasts across the years are given in 
Table 4. It can be seen that during last four seasons, RS based 
forecasts deviated from post-harvest estimates by 0.9, 42.1, - 
5.4 and +0.1 Mt only. 
Table 4: The results of final production since 1996 are 
summarized in the following table. 
  
  
  
  
  
  
  
  
  
Your NWPF (RS) DES 
ACR(Mha) PRO D(Mt) | ACR(Mha) PROD(Mt) 
1995-961 27.261 |  ----- 25.01 62.1 
1996-97 26.093 64.979 25.89 69.35 
1997-98 26.2 67.27 26.7 66.35 
1998-99| 26.603 72.876 27.4 70.78 
70.10(M ar) 
1999-00 26.884 70.203 26.74 to 
75.6 (Jun) 
2000-01 24.291 68.373 24.96 68.46 
73.53 (Apr 
2001-02} 26.423 73.568 25.8 05, 2002) 
  
  
  
  
  
  
5. SPATIAL ANALYSIS OF CROP GROWTH 
DIFFERENCES 
The difference of vegetation index of comparable dates 
provides information about crop status vis-à-vis previous 
season. This type of analysis over multiple dates during 
previous years has been useful in identifying crop shifts (Rajak 
et al., 2000; Rajak et al., 2002), changes in sowing dates and 
vigour of crop. Similar analyses were carried out from time to 
time and were communicated to Ministry of Agriculture, 
Government of India, along with results. The crop assessments 
cover change in extent and vigour of the crop and major 
observations in previous years include (a) late sowing in parts 
of Bihar during 1997-98, (b) early sowing in parts of Haryana 
during 1999-2000, (c) decrease in mustard area in East 
Rajasthan during 1999-2000, (d) mustard -wheat crop shift in 
parts of Rajasthan during 2000-01, and (e) decrease in wheat 
area due to drought in Western MP during 2000-01. The 
consolidated highlights across the years are given in Table 5.