Chintapalli, S.M. 
  
canal (2) Age of lining of water course (3) Extent of lining i.e., per cent of lined area of water course. The location of water 
course in the parent canal will be in “Head Reach Area (HRA)”, if the water course off takes from the first 1/3 rd length 
a of the parent canal. Similarly, if the water course off takes from the last 1/3 rd length of the parent canal, it is called “Tail 
Reach Area (TRA)” and lastly, it is called “Mid Reach Area (MRA)”, if it off takes from the middle 1/3 rd length of the 
parent canal. The water courses located in the HRA of parent canal perform better than that located in the TRA of parent 
canal due to better water availability. As the age of lining increases, the performance gets deteriorated. The water courses 
which were lined to a greater extent perform better than those lined to a lesser extent i.e., the per cent of lining and 
performance are directly related. The performance of water courses in the post-lining period is significantly better than that 
in the pre-lining period. 
3.3 Satellite derived indicators of agricultural performance 
In the current study, five indicators of performance were developed. These indicators were derived for remote sensing data. 
They are (1) Wheat crop Intensity (WI), (2) Equivalent Wheat crop Area Intensity (EWAI), (3) Sustainability in crop 
intensity, (4) Tail - Head Ratio of NDVI (THR py), and (5) Coefficient of variation of NDVI (CV py). The first three 
indicators are crop area based and the last two are crop condition based. 
3.3.1 Wheat crop Intensity 
Wheat is the most preferred crop in the study area. Subject to the availability of sufficient irrigation water, farmers 
generally prefer wheat crop to non-wheat crop. Hence the extent of wheat crop is directly related to the degree of 
. availability of irrigation water. The typical trends 
in wheat intensity in two of the water courses are 
shown in figure 2. It was observed that the 
intensity of wheat crop was influenced by the 
location of water courses in the respective parent 
canal. Water courses off taking from the head 
reach areas have increasing wheat intensity over 
time while water courses in tail reach area have 
declining wheat intensity. Water courses which 
were lined recently i.e., after 1992 have shown 
significant improvement in wheat intensity in the 
post-lining periods. In the water courses which 
were lined in 1975-76, there was no clear relation 
between wheat intensity and age/extent of lining. 
However, in this group, location of water courses seems to be an important factor i.e., water courses located in the head 
reach area of respective distributary / minor have higher wheat intensity. 
Water Course 1 Water Course 2 
8 
  
  
70 + | 
8 5 
3 
% of Wheat 
8 8 
% of Wheat 
8 8 8 
o 
eo 
   
Figure 2. Typical trends in wheat intensity 
in two water courses 
3.3.2 Equivalent Wheat crop Area Intensity 
EWAI is the index which expresses the total crop area in terms of wheat crop area to facilitate easy and straight forward 
comparison of cropping intensity and irrigation water consumption. The non-wheat crops acreage was converted into wheat 
with the factor 1 acre of non wheat = 0.6 acre of wheat, which is approximately proportional to the ratio of their average 
irrigation water requirements. In the current study, EW AI was found to be influenced by the location of water courses with 
head reach area water courses having more crop area and tail reach area water courses having less area. In the water courses 
having same age of lining but different length of lining, the EW AI is more in water courses though the length of lining is 
less because of its location in HRA. Thus the factor of location of water course looks to be having more influence than 
extent of lining. The EWAI was more in an unlined water course located in head region than lined water courses located 
elsewhere. 
3.3.3 Sustainability in crop intensity 
The coefficient of variation (CV) in crop intensity during 1986-87 to 1996-97 reflected the sustenance in irrigated 
agriculture. Temporal changes in crop intensity could be attributed to changes in water availability. High values of CV 
signify inconsistent/deteriorating performance. The values of CV at water course level as well as at head and tail reaches 
iore within water courses for the water courses which were lined before 1986 are presented in table 1. The CV values up to 10 
ere percent may be considered insignificant. 
rent 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 267