This year’s monsoon showers have brought smiles to many but distress to some. As predicted by the India Meteorological Department, the monsoon has spelled its bounty across the nation. However, excessive rain in some regions has led to severe floods. Gujarat and neighboring areas namely Banaskantha, Ahmedabad, Gandhinagar, Mehsana, Patan, Sabarkantha, etc., has recorded more than 300% rainfall above average level during July 20 to July 26.
ISRO has used the SCATSAT-1 to track flooding across the nation during the monsoon, with a special focus on Gujarat and Rajasthan. It has also extensively tracked monsoon activities in West Bengal, Uttar Pradesh, Assam and Bihar. The satellite used data based on backscattering and brightness temperatures of the Earth to monitor the flood situations. ISRO was able to capture a high-resolution dataset by scanning overlapping areas with the satellite.
SCATSAT-1 uses data based on backscattering and brightness
Merging of backscattering and brightness temperature data helped to delineate the regions, which were flooded, partially submerged or existed in different soil wetness conditions (saturated or dry). Inundated areas have been obtained during the second week of July over Ganga (Kanpur to Patna and Kosi river) and Brahmaputra flood plains. Extreme flooding conditions were observed in Ahmedabad, Mehsana, Kheda, Banskantha, Bhavnagar as compared to relatively dry conditions in Bharuch during the fourth week of July along with moderate inundation in parts of West Bengal.
Better coverage by SCATSAT-1 than INSAT-3D/3DR
Optical remote sensing from the geostationary platform (INSAT-3D/3DR) provides observations of cloud cover and rainfall but is unable to image the inundation on the ground through the thick clouds during monsoons. The instruments on the SCATSAT-1 were able to penetrate the cloud cover to make the necessary observations. The data from the SCAT-SAT-1 was correlated with observations from the Sentinel-1A, which is an earth observation satellite equipped with a Synthetic-aperture radar. ISRO has provided an animation of the floods during June 2017.