Iat S/n 
13 2.6 
15 3 
12 3 
9 225 
12 2.4 
13 2.6 
13 2.6 
12 3 
12 3 
11 2.75 
12 3 
10 2.5 
12 3 
12 2.4 
10 2 
13 2.6 
10 2.5 
11 2.2 
12 2.4 
12 24 
12 24 
14 2.8 
7 1.75 
11 22 
13 2.6 
9 1.8 
10 2 
8 2 
6 1.3 
11 22 
10 2 
9 1.8 
10 2 
10 2:5 
12 3 
10 2.5 
8 2 
9 2.25 
8 2 
7 1.75 
9 2.25 
11 2.2 
7 1.75 
8 2 
6 1.5 
9 2.25 
10 2.5 
  
  
geomorphic index, the indices are arbitrarily divided into three 
classes - class one with higher geomorphic index, class two with 
moderate index and class three with lower index (Table 1). 
Relative tectonic activity classes (lat) obtained by the average 
(S/n) of different classes of geomorphic indices and classified 
into three groups - group I shows high tectonic activity with 
values of S/n < 2; group II shows moderate tectonic activity 
with S/n > 2 to < 2.5; and group III shows low tectonic activity 
with values of S/n > 2.5 (Figure 7). Extensive fieldwork has 
been carried out to find out the evidences in order to confirm 
the tectonic activity. Field evidences such as deep valleys, 
sudden changes in the river course and waterfalls at fault planes 
clearly agree with the values and classes of tectonic geomorphic 
indices. Geomorphic indices computed from DEM using GIS 
are found to be suitable for identification of neotectonic activity 
in the Precambrian terrain of western Ghat regions of India. The 
low tectonic activity class 3 of Iat mainly occurs in the middle 
and lower parts of the basin, whereas high tectonic activity 
classes 1 and 2 occur in the upper part of the basin. 
  
x 
À 
    
121640" 
12° SON 
Legend 
Relative tectonic activity class 
Stes | 
  
1153'20"N. 
   
  
  
  
T5'Hr20"E. 78°30 CE TSATAOE ?T5"3T20"E 
Figure 7. Relative tectonic activity classes. 
5. CONCLUSION 
An attempt has been made to utilize SRTM data and 
interpretation techniques of GIS to determine the geomorphic 
indices and its influence on tectonic activity in the 
Valapattanam river basin of northern Kerala, India. The analysis 
carried out by GIS and remote sensing methods helps us to 
determine the geomorphic indices of the drainage basin digitally 
and confidently. Five geomorphic indices - stream length- 
gradient index (SL), asymmetry factor (Af), hypsometric 
integral (Hi), drainage basin shape (Bs) and valley floor width- 
to-height ratio (Vf) — were analyzed. Geomorphic indices 
computed from DEM using GIS are found to be suitable for 
identification of neotectonic activity in the Precambrian terrain 
of Western Ghat regions of India. The low tectonic activity class 
3 of lat mainly occurs in the middle and lower parts of the 
basin, whereas high tectonic activity classes 1 and 2 occur in the 
upper part of the basin. 
ACKNOWLEDGEMENT 
The authors wish to thank Mangalore University for providing 
financial assistance for attending the ISPRS 2012. 
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