Flood Hazard and Risk Zonation in North Bihar Using Satellite-Derived Historical Flood Events and Socio-Economic Data

Abstract

North Bihar is one of the most flood-affected regions of India. Frequent flooding caused significant loss of life and severe economic damages. In this study, hydroclimatic conditions and historical flood events during the period of 2001 to 2020 were coupled over different basins in North Bihar. The main objective of this study is to assess the severity of floods by estimating flood hazards, vulnerability and risk in North Bihar. The uniqueness of this study is to assess flood risk at the village level as no such study was performed earlier. Other thematic data, namely, land-use and drainage networks, were also utilised with flood maps to validate the severity of the event. MOD09A1 satellite data (during 2001–2020) derived indices were used to derive inundation extents and flood frequency. Socio-economic vulnerability (SEV) was derived based on seven census parameters (i.e., population density, house-hold density, literacy rate, agricultural labour, and cultivator, total male, and female) and coupled with flood hazard to derive flood risk over the study region. The study exhibited that a total ~34% of the geographical area of North Bihar was inundated in the last 20 years and the maximum flood extent was seen in 2020. Flood risk map exhibited that ~7%, ~8%, ~13%, ~4%, and ~2% of the geographical area was mapped under Very High, High, Moderate, Low, and Very Low categories, respectively. The 2770 and 3535 number of villages was categorized under Very High and High flood risk zone which are located in north-central and central-western regions. These findings can be applied to distinguish and classify areas of various risk zones to assist in flood mitigation and management activities.

Google Earth Engine for Large-Scale Flood Mapping Using SAR Data and Impact Assessment on Agriculture and Population of Ganga-Brahmaputra Basin

“…These results show that the flood extent map was accurate to that seen in the optical FCC images as well as the greycolor images of the SAR data (Figures A2 and A3). Moreover, these results are consistent with the latest study, which has reported based on the MODIS NRT flood product that about 17.7% of the geographical area of North Bihar was inundated during 2020 flood events and the adversely affected districts were Muzzafarpur, Darbhanga, Saharsa, Khagaria, Madhepura, Bhagalpur, Katihar, and Purnea [62]. Previously, during the flood event of August-September 2017, 12% to 17% of the geographical area of North Bihar was inundated during the peak flood period [57].…”

“…The present study showed that the floods in 2020 have affected the croplands area between 23.68% (Bangladesh) to 28.47% (Assam) and the built-up area between 5.66% (West Bengal) to 9.15% (Assam). Most of these results are in line with previous studies that have reported the impact of floodwater on agricultural land and urban areas, especially in Bihar [34,62]. The flood impacts in North Bihar during the 2017 flood events were the highest in agriculture (19%), followed by the forest (0.58%) and built-up classes (0.4%) [42].…”

Flood Hazards Assessment and Residential Flood Damage Mapping in Hitoyoshi Prefecture, Japan

“…This study aims to provide an overview of disaster risk assessment using a flood inundation map in the Hitoyoshi area. Inundation or flood can be defined as an area of an overflow of a body of water that is normally dry but becomes inundated by overflowing rivers (Tripathi et al, 2022). The information obtained from this study provides an overview of each location's vulnerability to create a better environment.…”

“…Flood hazard is defined as the severity of an area against flooding which is indicated by the inundation area, inundation depth, and inundation duration (Tripathi et al, 2022). Other factors that are directly related to the flood hazard are social and economic related factors, especially areas related to land functions consisting of residential areas, commercial areas, industrial areas, areas that are public in nature, and other supporting areas (Abdulharis et al, 2022).…”

Flood Reduction and Prevention Possibilities in the Flood Plains: A Case study of the Varuna River Basin in the Flood Plain of the Ganga River, Uttar Pradesh, India

“…Althoughthe National Remote Sensing Centre has produced ood-hazard atlases for several states includingAndhra Pradesh (2022), Assam (2011 and 2016), Bihar (2020), Odisha (2019), Uttar Pradesh(2022) and West Bengal (2022),detailed maps of ood-prone areas, particularly oodplainsof large rivers are lacking in India.However, detailed ood-prone area maps for some discrete areas along the Ganga Riverwere created by several authors (Tripathi et al 2022;Mishra et al, 2022;Das and Sar, 2020;Mohan et al, 2011). It is important to note here that money spent on disaster-preparedness is more cost-effective than money spent on post-disaster relief and reconstruction (Hawley et al, 2012).…”