(GIST OF SCIENCE REPORTER) GIS and Remote Sensing in Disaster

[JUNE-2022]

As per the estimate of the United Nations Office on Disaster Risk Reduction (UNDRR), combined economic losses from disasters such as earthquakes, tsunamis, cyclones
and flooding range somewhere between US$ 250 billion to US$ 300 billion annually. This amount may increase in future under the influence of changing climatic conditions. Therefore, nations across the world have to develop management plans for each individual disaster they are susceptible to. This management plan highlights the steps to be taken before the disastrous event, during the disastrous event and after the event. This exercise has been considerably aided by the advent of new technologies such as Remote Sensing (RS) and Geographic Information System (GIS).
Spatial data information acquisition is a prerequisite for disaster management. Combined with GIS techniques, RS can be used in many ways to assist in disaster management response as a tool. In addition, various spatial analysis tools in GIS help to understand the geography of the disaster and provide quick and effective understanding of emergencies.

Landsat images were used to assess the impact of urbanisation on the natural ecosystem over three decades in Shillong. Our analysis shows that during the last thirty years, the built-up area increased significantly, taking up the area under the vegetation cover. It can be seen that the Southern and Eastern part of the city had an increase in the built-up area.
This may also suggest that these areas in future may have increased events of flash floods due to the loss of vegetationand increased urbanisation.

Land Surface Temperature (LST) maps were developed using the thermal infrared band of Landsat 8 data and the ambient air temperature maps using the data measured
by the AWS (Automatic Weather Stations) unit, to understand the spatial distribution of land surface and ambient air temperature in Rajkot, Bhubaneshwar & Delhi for 2018-2019 summer period. These thermal hotspot maps were used to identify vulnerable heat hotspots for mitigation actions by local municipal corporations.

A study was carried out in collaboration with the North Eastern Space Applications Centre (NESAC) and GB Pant National Institute of Himalayan Environment and Sustainable Development (GBPNIHESD)-Sikkim Regional Centre (SRC) to map the vulnerability of two northeastern cities, viz. Gangtok and Shillong, to various disasters. In this study, the disaster vulnerability of the cities was mapped using high-resolution Worldview-2 satellite imagery and Cartosat version-3 DEM at a 1:4000 scale.
Our work led to the identification of wards that are more susceptible to disasters like landslides and floods in the two cities. An integrated GIS-based Multi-Criteria Decision Analysis (MCDA) using slope, aspect, elevation, land use/land cover, landslide inventory, lineaments, and drainage density was employed.

There are scores of other applications of RS and GIS apart from the ones mentioned above. The terrain information obtained using the DEM (Digital Elevation Model)/DTM (Digital Terrain Model) is extremely useful for developing slope and aspect maps. These maps then act as input layers for developing hazard models in mountainous regions. The potential of RS and GIS in disaster management is endless.
We need to employ these state-of-the-art technologies for societal benefits at a large scale throughout the country. Disasters can wipe off years of progress and it is important to integrate applications of GIS and remote sensing for designing and developing disaster resilience across the cities as well as communities.