Floods mostly vary from one region to another, and their severity is determined by a variety of factors, including unpredictable weather patterns and heavy rainfall occurrences (Pham Van and Nguyen-Van, 2020; Soulard et al., 2020).
Although floods are common in many places of India during monsoon seasons, the Ganga basin is particularly vulnerable
(Bhatt et al., 2021; Meena et al., 2021). There are a lot of areas in the state of Bihar that get flooded due to the swelling of
rivers in neighboring Nepal (Lal et al., 2020; Soulard et al., 2020; Wagle et al., 2020). This appealed to the attention of the
present research. The Ganga basin spans China, Nepal, India, and Bangladesh (Agnihotri et al., 2019; Ahmad and Goparaju,
2020; Prakash et al., 2017; Sinha and Tandon, 2014).
The global emergence of COVID-19 has stopped all the activities, and it debuted as the deadliest disease with the
longest nationwide lockdown. These caused enormous disruption in all aspects of people’s livelihood. Besides, major
obstacles got accumulated due to the effect of the flooding event during July 2020. It added misery to the people and livelihood of the people, who were trying to control the spread of COVID-19. These results in disaster-risk mitigation to other
sectors. The only way to have an effective and prompt response is to have real-time information provided by space-based
sensors. Using a cloud-based platform like Google earth engine (GEE), an automated technique is employed to analyze the
flood inundation with Synthetic Aperture Radar (SAR) images. The study exhibits the potential of automated techniques
along with algorithms applied to larger datasets on cloud-based platforms. The results present flood extent maps for the
lower Ganga basin, comprising areas of the Indian subcontinent. Severe floods destroyed several parts of Bihar and West
Bengal affecting a large population. This study offers a prompt and precise estimation of inundated areas to facilitate a
quick response for risk assessment, particularly at times of the COVID-19.
The three states (Bihar, Jharkhand, and West Bengal), collectively known as the Lower Ganga Basin, are home to more
than 30% of the population (Prakash et al., 2017). Rapid population growth and settlements resulted in changes in land use,
increased soil erosion, increased siltation, and other related variables that augmented flood severity (Li et al., 2020; Pham
Van and Nguyen-Van, 2020). However, floods became the most frequent disaster in recent times, what compounded the
problem was the COVID-19 pandemic (Kr€amer et al., 2021; Lal et al., 2020). As a result, new measures were needed to
manage the spread of COVID-19 as well as flood mitigation (Wang et al., 2020; Zoabi et al., 2021). Although ground data
and field measurements are considered to be more accurate, they are time and money consuming. Furthermore, field
surveys were impossible to conduct during this period, since social distancing has become the norm, linked with significant
health concerns and trip expenditures ( Jian et al., 2020; Lattari et al., 2019). Flood mitigation strategies that are ineffective
may result in more human deaths, property damage, and more spread of COVID-19 (Cornara et al., 2019; Shen et al., 2019).
It had disastrous impacts in 149 districts throughout Bihar, Assam, West Bengal. Since the movement was halted owing to a
sudden shutdown, the only way out was to employ robust flood control techniques based on real-time information (Das
et al., 2018; Dong et al., 2020; Tang et al., 2016). The dramatic increase in flood occurrence in these locations prompted
specialists to implement more structured and effective flood management to address the issues, while also adhering to all
COVID-19 norms and regulations (Min et al., 2020; Wang et al., 2019).