Applications of Remote Sensing and GIS

1. Determination of the Gay affected area using GIS/SPANS


It is essential to accurately define the are under the destruction of the Gay for this study. Too large the are would be time consuming whereas the smaller area might not be sufficient for a sound conclusion and recommendation to be made. The following steps therefore were taken to identify the disaster area.


1. The track of Gay and its radius of 50 km (0n 4th November) as reported by the Meteorological Department were entered into the GIS/SPANS to define the coverage of the damage area which extended 50 km from bothsides of the center lien of movement. The resulting damaged zone when overlaid on 1:50,000 map index is as shown in figure 1.



2. The damages zone was subdivide further into 2 levels according to the information obtained from the preliminary ground survey conducted between 23-26 November 1989. The first level is the zone extending 30km from the center line of movement where the damages were between 50-100%, and the second is between 30-50 km with lesser damages of 0-50%.



3. By overlaying the administrative boundary map and the damaged zone map with GIS/SPANS, the extent of damages in districts under the sweep of Gay could be assessed (as shown in figure 3). It was found that the total damaged are within the 50 km radius is about 4,605.4 sq.km and the at Amphoe Pathiu and Amphoe tha-sae in Chumporn province were most affected with 50-100% damages.