Digital analysis of satellite data in water resourses studies
A.K. Chakraborti
Water Resourses Division
Indian Institute of Remote sensing
Dehradun 248001, India
B. Ganbaatar
State Committee for Environment Control
UlaanBaatar, Mongolia
Abstract
Digital analysis of satellite data is studied from the point of view of selecting optimum band (s) and or band combination (s) through several enhancement techniques for water in two states , namely , snow / glacier ice and surface water in a reservoir . study areas are : Gangotri glacier in central himalaya and pong reservoir in Himachal Pradesh , in India . It is seen that , amongst several individual bands & their FCC combinations of 7 bands TM CCT data , FCC (456) provides best information on glacier ice / snow cover condition and secondly , FCC of certain transformed functions ( logarithmic , exponential , principal component ) of IRS-1A LISS-ICCT data provide qualitative aspect of water-depth donation in the reservoir .
1. Introduction
Remote Sensing data have been utilised for water resources studies over the last two-decades . In these studies , both image interpretation techniques and digital analysis methods are employed . But yet there is not enough comprehensive documentation on methodology and analytical tool which should minimise human effort , computer time & cost while dealing with remote sensing data to solve a typical water resource problem .
The utility of digital analysis of satellite remote sensing data in water recourses studies is now well recognised . Because , this mathod is fast , produces , accurate mapping , and can depict subtile changes in water & land regimes vital for water recourses monitoring & decision making . However , with so many new types of satellites / sensors now available , it is not very definitely known to a water recourses investigator , which spectral band or combination or bands are most useful , which enhancement or classification procedure are to be applied, what level of accuracy one can be discerned while addressing a particular water recourse problem ?
Water in two states , snow / ice field and surface water body are of absorbing interest since the early days of satellite remote sensing , because of their unique spectral characteristics in the entire range of electromagnetic wavelength regions , temporal variation within day / season opportunity to capture synoptic view of the entire water body/ice mass and easy way of digital manipulation of satellite data , compared to other complex terrain features . Over 600 , 000 sq . km . area in the
Himalayas is snow-bond , situated at 2500 metre above mean sea level . More then 900 large & medium size reservoirs with a storage capacity of 17 million hectare metre have been built in India . Therefore , studies of water in these two states are important .
Two independent studies in Indian situations with limited objective of using digital analysis of satellite data to select .
optium band / band combinations are presented in this paper : i) glacier ice / snow cover identification in gangotri glacier in Himalayas ii) water-depth zonation in pong reservoir in himachal pradesh . At this stage , no effort is made to collate digital data analysis & finding with ground-truth information .
