IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India, 2002 
is superior for identifying within wetland features or structural 
components such as open water and wetland vegetation. 
  
  
Fig. 1: Nalsarovar (top-IRS view and bottom field) 
1.1 Rainfall 
The rainfall distribution pattern determines water spread and 
relative abundance of various habitat types in the lake. Nal 
Sarovar falls in drought prone area and has low and highly 
erratic rainfall pattern. though the quantum of water is 
sometimes made up by brackish water brought up by feeding 
rivers. Table 1 and Fig. 2 gives annual rainfall distribution at 
Sanand, a taluka place that is about 30 km from the Nal 
Sarovar. 
Table 1: Yearly Rainfall (mm) at Sanand 
  
  
  
  
  
  
  
  
  
  
  
Year Rainfall Year Rainfall 
1981 813.8 1991 628 
1982 330 1992 620 
1983 653.1 1993 838 
1984 692.1 1994 1192 
1985 370 1995 459 
1986 233 1996 683 
1987 155 1997 1124 
1988 558 1998 645 
1989 612.5 1999 717 
1990 862 
  
  
  
  
  
  
Source: Department of Agriculture, Gujarat 
From the above table and graph it is apparent that rainfall was 
lowest in 1987 and 1986 (drought years) and during those years 
604 
Nal Sarovar is reported to have completely dried up. 
  
  
T 
  
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Yea | 
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Fig.2: Rainfall pattern at Sanand | 
  
  
2. SATELLITE DATA USED 
Satellite data pertaining to 1985, 1986, 1988, 1992 and 1996 
have been used in order to map and monitor structural 
components of Nal Sarovar wetland. Land use map of the 
catchment was prepared using satellite data of May and 
November 1998, Details are given in Table 2. 
Table 2: List of satellite data used for Nal Sarovar 
  
  
  
  
  
  
  
  
  
  
  
  
Sl. Satellite/ Path-Row Daie 
No. | Sensor 
l. Landsat TM 149-044 Jan 29, 1985 
2. IRS 1A 032-052 Dec 30, 1988 
3. IRS 1A 032-052 Sep 24, 1992 
4. IRS 1D 092-056 May 24, 1998 
S. IRS 1C 092-056 Nov 25, 1998 
3. METHODOLOGY 
Visual analysis techniques were used to study structural 
components of wetlands, and also to prepare land use map of 
the catchment. 
3.1 Structural Components 
Structural components of a wetland depict the diversity of 
habitat types and its health. They also play a significant role in 
deciding ameliorative measures for conservation. Detailed 
studies using multi-temporal satellite data have been carried out 
on 1:50 000 scale for monitoring of structural components 
(water spread, aquatic vegetation, islets, mud flats etc.). For 
monitoring purposes base map was prepared using SOI 
topographical maps (on 1:50 000 scale) and the maximum 
water spread area from the IRS image. This map was used as a 
reference for comparing structural components (water, aquatic 
vegetation, mud/salt flats, edges, islets etc.). Optical 
enlargement equipment (PROCOM-2) was used to enlarge the 
FCC. The exercise was repeated for all the available satellite 
data. 
3.2 Land use/ cover mapping 
Catchment characteristics are highly significant, as there is a 
continuous flow of matter and energy from the catchment to the 
wetland. Among the catchment characteristics, land use is very 
dynamic and plays major role in maintaining health of the 
wetland ecosystems. Nal Sarovar is a natural depression and 
slope is very gentle in its catchment. Catchment boundary of 
the Nal Sarovar was approximated using spot heights, drainage