High Resolution Remote Sensing Data & GIS Techniques in Updation of Infrastructure Details for Flood Damage Assessment - A Case Study
YK Srivastava, Binod Doley*, DK Pal, RK Das**, S Sudhakar, S Adiga ***
KV Venkatachary***, SK Srivastava***
Regional Remote Sensing Service Centre, ISRO,
Department of Space, IIT - Campus, Kharagpur - 721 302,
West Bengal, India, Phone: (O) 91-3222-55644, (R) 91-3222-78225,
Fax: 91-3222-77210, E-mail: srivastava_yk@yahoo.com
* SRF in Indian Agricultural Research Institute, New Delhi, India.
** Presently working under government of Botswana.
***Department of Space, ISRO Headquarters, Bangalore, India.
Keywords
Infrastructure, GIS, Remote Sensing, Flood Damage, Brahmaputra River, Disaster, IRS -1C /1D, LISS -III, PAN
Abstract
There are several natural disasters occurring throughout the world round the year and causing huge loss to the lives, property and natural resources. Assessment of damage caused by these disasters needs to be carried out accurately in minimum possible time frame. Space technology is one of the best-suited means for the assessment of damage brought about by natural disasters. Remote sensing satellites provide synoptic view, repetitive coverage and high-resolution images. This advanced high-resolution sensor technology has provided immense scope to the earth resource scientists world-wide for mapping and analysis of earth surface feature details using Remote Sensing and Geographic Information System (RS & GIS). India is among several countries in the world, which face severe problem of floods every year particularly in the river basin of Ganga-Brahmaputra.
Considering the seriousness of the flood problem, Department of Space / Govt. of India has taken very important step to develop and implement an effective Disaster Management System (DMS). One of major activities under DMS is to provide flood damage assessment and to assist in flood mitigation/ protection work. North - Eastern part of India and especially the Assam State is most prone to flood due to its delicate geographic location in the Bramhaputra valley. The mighty river Brahmaputra travels approximately 720 km in Assam from east to west with its perennial flood menace during monsoon that affects almost 20 districts out of a total 24 districts in the state of Assam. Marigaon district of Assam, which is taken as the case study is one of the worst affected districts. Almost 60 % of the district get inundated during flood season causing untold human sufferings and heavy loss to animal lives, property and natural resources worth several million rupees. Indian Remote Sensing Satellite (IRS) - 1C / 1D high resolution PAN, LISS- III, WiFS data and topographic maps on 1: 50,000 scale are used in carrying out this study. Initially digital map database is prepared for geometric rectification of PAN, LISS- III and WiFS data. Further this map database is utilised in digitizing infrastructure details. Merged products of PAN+LISS- III are generated and used for extraction of infrastructure details in GIS environment, i.e., settlements, metal and unmetal roads/ cart tracks, rails, embankments/ dykes and causeway. Apart from infrastructure details, natural features were also digitized, i.e., drainage, ox-bow lakes, streams, river, river islands, tanks and reserve forests boundaries. WiFS data is used for extraction of flood layer and the resultant flood layer is used along with all infrastructure layers to intersect the inundated area and assess the damage. Classified landuse/ landcover (level III) map generated from LISS - III data is used to assess the damage to agricultural crops.
1. Introduction
Almost all the countries in the world are prone to one or more forms of disasters viz. earthquakes, cyclones, volcanic eruptions, drought, landslides, flood etc. India is among several countries in the world that faces multiple facets of such disaster almost every year. The region, facing floods during monsoon is often subjected to severe drought during lean season. Northern and North-East part of India which fall under Bramhaputra - Ganga river basin is prone to floods. Floods in these areas directly or indirectly affect the economy of the country either in the form of natural resources, lives, property or infrastructures such as houses, roads, railways, pipelines, electricity and telecom network.
Bramhaputra River is among the largest rivers in the world. This river originates from the glacier of east Manasarovar and travels nearly 1100 km across the Tibet before entering in India through the eastern part of Arunachal Pradesh. After another 226 km of mountainous journey in Arunachal Pradesh, this mighty river enters in Assam State near Pasighat and travel 720 km in the state from east to west direction and finally leaves Assam at Dhubri district to enter Bangladesh. Bramhaputra River is almost 2880 km long from its origin to out falls in Bay of Bengal. Floods in Brahmaputra River have been aggravated due to frequent change in river course, bed topography and heavy sedimentation load. As reported by the state Govt. that during August - September 1998 people of Assam State have experienced one of the most devastating flood conditions after 1950. This flood had affected a total of 50,000 population, 16,000 houses in 5,126 villages of 21 districts and claimed nearly 156 lives and inundated 2.21 lakh hectares of crop area for about two weeks (DMS Report phase-1 January1999).
In recent years, this has been observed and proved that the space technology is the only means for the mapping, analysing of flood affected area and for providing earliest information to various agencies for carrying out relief rehabilitation measures and for restoration of normalcy. Because, today remote sensing satellites are equipped with high-resolution sensors that can provide finer details of ground with synoptic view and repetitive coverage (Venkatachary KV et al 1999).
Disaster Management System (DMS) conceived by the Department of Space / Govt. of India has been playing a very important and effective role towards flood damage assessment and providing assistance in flood mitigation/ protection work. Infrastructure details on 1: 50,000 scale topographic maps particularly in these areas where floods and migration of river channel are very common, are invariably out dated and over a period of 30 -35 years no updation has been done. If updated, these details can play very important role in assessment of damage. It is very difficult to assess the damage in total without having current information of infrastructure details. Therefore it was decided under DMS project to obtain current information of the infrastructure details using both existing maps on 1:50,000 scale as preliminary base and high resolution panchromatic remote sensing data of IRS - 1C /1D for updation of such details. IRS - 1C /1D, LISS - III data are used for generation of landuse / landcover map for assessment of crop damage. The present study has been carried out with following objectives.
- To assess the utility and capability of IRS 1C / 1D high resolution data for mapping of
infrastructure details such as metal and unmetal roads/ cart tracks, settlements, railways and causeways.
- To monitor changes in natural feature using existing topographic maps and IRS 1C / 1D high-resolution data.
- To undertake damage assessment of 1998 flood.
