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(Anonymous, 2001).Sonneratia apetala and Rhizophora 
. lamarckii have become rare and nearing extinction 
(Kannupandi and Kannan, 1998). Several studies provided 
different estimates of degradation in different span of time but 
actual cause for the degradation need to be ascertained. 
Kannan et al (1998) estimated that 62.8% of 700 ha had 
degraded during 1987 to 1994 with the aid of Survey of India 
map and IRS IB LISS II data. Ramachandran and 
Krishnamoorthy (1999) had attempted to demarcate mangrove 
zonation in Pichavaram using TM and ERS-1 SAR and 
reported that the SAR data was less useful in defining 
mangrove areas due to differential back scattering by mangrove 
canopy. Centre for Rural Education and Environmental 
Development (CREED) had reported that the original 1,300 ha 
cover of Pichavaram mangrove forest was reduced to 260 ha. 
The degradation of Pichavaram mangrove was attributed to 
human encroachment, charcoal production, fodder gathering 
and cattle grazing (Anonymous, 2000). 
  
Figure-1 Location of Pichavaram mangroves 
M. S. Swaminathan Research Foundation (online) report 
attributed physical factors such as seasonal closure of the 
estuaries mouth and reduction in freshwater flow for the 
degradation of mangrove wetland of Pichavaram rather than the 
social causes. Based on water quality study, Purvaja and 
Ramesh (2000) concluded that the fast degrading of mangroves 
was due to natural and dominantly anthropogenic factors, like 
damming of water in the upstream of the river Cauvery for 
farming, leading to reduction in sediments supply needed for 
mangrove vegetation. It was also reported that sea level rise of 
approximately 1.5 mm/year leading to reduced tidal currents, 
erosion of the substratum and increase in soil salinity might be 
the causes for degradation of mangrove forests. Singh (2001) 
had indicated that in Tamilnadu 47 sq. km of mangrove was 
reduced to 21 sq. km during 1991-93 as per Forest Survey of 
India estimates, of which Pichavaram forest forms a major 
portion. During 1987 the Tamilnadu Forest Department 
declared this zone as reserved forest. Since then no holistic 
conservation and protection measure was taken up by 
425 
addressing all the possible issues for degradation barring efforts 
taken up by Tamilnadu Forest Department, MSSR Foundation 
and CAS in Marine Biology, Annamalai University, as per 
available reports. Albeit, at this juncture, it is appropriate to 
relook into the current status of Pichavaram mangroves, their 
spatial extent, distribution and cause for the degradation. 
Protection and conservation of Pichavaram mangroves and 
restoration of the ecosystem require management solutions 
purely based on the scientific analysis. 
The zonation of the mangroves depends upon many factors like 
morphology, hydrodynamics and other environmental 
parameters in the intertidal region. Using remote sensing data it 
was possible to identify different zones of degradation during 
different time periods and address issues related to land use and 
land cover changes due to developmental activities in the 
coastal zone. Geographic Information System (GIS) is a 
powerful technological tool for the integration of spatial data 
like mangrove zonation, degradation, loss, land use and land 
cover changes with non-spatial data like environmental 
parameters and socio-economic data. Integration of mangrove 
zonation, coastal morphology, hydrodynamics, environmental 
conditions and socio-economic status of the region would 
provide worthwhile solutions for the management of the 
mangroves of Pichavaram. 
  
Figure-2 Geography of Pichavaram mangrove environment 
in IRS-1D, LISS data. 
Classification of mangrove forest using Thematic Mapper data 
is a proven technique (Sato and Kanetomi, 2000) but this study 
attempted to classify different zones of the mangroves using 
IRS-1D LISS III data. The Survey of India Topographic sheet 
published in 1970 was used as a baseline information on spatial 
distribution of the Pichavaram mangroves as the earliest 
information available in reliable scale and accuracy. Using 
23.5-metre resolution IRS-1D LISS four-band data of 1998, the 
mangrove of Pichavaram was classified into three major zones 
using unsupervised training sets. From the above classified 
clusters, homogenous groups with more than 2 x 2 pixel