Full text: Remote sensing for resources development and environmental management (Volume 2)

781 
19° 
73°W 
lents in the 
which appear 
id the river. 
5 DISCUSSION 
The coastal scenery as depicted by ¿he sate 
llite imagery is one of a highly indented 
shoreline with creeks, promontories, cliffs, 
bays and beaches. There are also extensive 
marshy tracts; at a few places along the 
coast, raised beaches occurring 3 m. above 
the present sea-level and a band of littoral 
concrete are observed at Versova and Madh 
promontory respectively. The creeks keep to 
NE-SW, north-south and NW-SE trends. 
The raised beaches, the littoral concrete 
and the marshes indicate a period of emer 
gence of the Bombay region sometime in the 
past. This might have occurred consequent 
on the coastal faulting which is generally 
believed to have taken place all along the 
West Coast after the eruption of the Deccan 
Volcanics; Radhakrishna (1957) has given a 
Miocene age to this fault. The resultant 
coastline must have been straight. 
This faulting, which represents a failure 
of the volcanics by rupture, has been prece 
ded by plastic deformation of the volcanics 
which is reflected in the monoclinal flex 
ure described by Auden (1949) , the Panvel 
flexure; this is an important lineament of 
the Konkan region. Subramanyan (1981) has 
shown on the basis of field evidence that 
the Thane Creek has developed over the ten 
sion fracture trending north-south that has 
formed along the axis of this flexure at the 
southern end. Concurrently, shear fractures 
trending NE-SW and NW-SE appear to have 
opened out in the volcanics in the Bombay 
region. These shear fractures have control 
led the courses of the creeks in the Bombay 
island and the adjoining Nhava-Sheva-Uran 
area in the east (Fig.2). In the latter area 
the lineaments intersect mutually to form a 
triple junction, cutting asunder the whole 
region and initiating the process of marine 
erosion. 
A retrogradation cycle of marine processes 
had set in subsequently and gradually conver 
ted the initially straight coastline into a 
highly irregular, indented shoreline of the 
'ria* type. Many bays have already been for 
med in the south - the compounded Back Bay 
and the perfect Mahim Bay. Due to intense 
urbanization in the Back Bay area, the ero 
siona! processes have been interfered with 
and they appear to have shifted their acti 
vity to the north. The intense erosion that 
is taking place south of Versova with a rhy 
thmic regularity every year appears to be 
partly due to this human interference. The 
Madh promontory also appears to be refract 
ing the waves on to this stretch of the coa 
st which lies on the same latitude as the 
former. Significantly, the localities to 
the north and south of this stretch are free 
from erosional damage. The growth of a spit 
from the mouth of the Malad Creek in the 
Versova area is interesting; for, it may be 
able to prevent the severe erosion south of 
Versova if it gains height when it will take 
up the brunt of the wave attack, itself. 
From this point of view as well as from the 
point of view of the suitability of this 
stretch for developing into an harbour, if 
required later, this spit is being monitored 
by Shetty and Subramanyan (1985). 
It is to be expected that, due to the ope 
ration of the retrogradation cycle, all the 
bays and promontories will be eliminated and 
that the coastline will restore its original 
straight configuration in a few million 
years. 
6 CONCLUSION 
Satellite remote sensing by itself has pro 
vided significant data adequate to trace the 
development and evolution of the Bombay 
coast. Supplementary data from the maps and 
field work have helped to complete the pic 
ture. 
REFERENCES 
Auden,J.B. 1949. Dykes in western India. 
Trans, nat. inst. sci. India. 3:123-157. 
National Atlas Organization. 1964. India: 
Physiographic regions, plate 41. 
Radhakrishna,B.P. 1967. The Western Ghats 
of the Indian peninsula. Proc. sem. geom. 
stud. India, univ. Sagar. 4-14. 
Shetti,Vi & Subramanyan,V. 1985. Spit simu 
lation - an approach for Yersova, Bombay. 
Sixth axm* ! meet. inst. Indian geogr. abs. 
Subramanyan,V. 1981. Geomorphology of the 
Deccan volcanic province. Mem. geol. soc. 
India. 3:101-116.
	        
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