Flood Monitoring Using Enhanced Resolution Passive Microwave Data: A Test Case over Bangladesh

Abstract

Monitoring floods is a major issue in water resources management and risk mitigation, especially in the Global South. Optical and radar observations, even providing a fine spatial resolution, are still limited by cloud cover interaction or insufficient temporal resolution. On the other hand, passive microwave (PMW) sensors collect information on a daily frequency with minor cloud cover interaction, but they have been historically limited in terms of spatial resolution. Here, we evaluate the capability of an enhanced spatial resolution PMW dataset (3.125 km) in monitoring spatio-temporal evolution of flood events, focusing on a major flood event that occurred in October 2005 in Bangladesh. We apply an algorithm aimed to remove the seasonal variability of surface temperature from the PMW timeseries, exploiting the difference in emissivity between dry and water-covered pixels. We assess the capability of the algorithm in capturing flood evolution and extension through the comparison with quantities obtained from optical data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and water level measurements. We also compare the enhanced product with the historical coarser resolution dataset by means of a variogram-based analysis to evaluate the improvements in terms of spatial representation. Finally, we evaluate the possibility to extract the water fraction within a single pixel by using an Advanced Microwave Scanning Radiometer—Earth Observing System (AMSR-E) emissivity dataset and compare the estimates with MODIS-derived water fractions. Our results show that the enhanced PMW product outperforms the coarser one when compared to flood mapped from optical data based on information content, indicating that it is possible to integrate such a product into the mapping of floods at a global scale on a daily basis.

Environmental Monitoring: Emphasis on Optical Waveguide and Fiber-Based Sensors: A Review

“…Flooding may be an attribute of a complex of dangers during extreme weather events that also include mudslides, gales, and tidal surges and causes much more havoc. Floods are the worst form of danger since they often occur, have a wide-ranging impact on every region of the earth, and are monster threats that don't simply happen once in a lifetime [7]. Low-magnitude, frequent floods can harm farmland, disrupt, or destroy buildings and infrastructure, stop business and other operations, expose people to health concerns, and so forth.…”

Mapping Floods during Cloudy Weather Using Radar Satellite Images

“…Sensors with high spatial resolution of greater than 3 m, such as TerraSAR-X, RADARSAT-2 and COSMO-Sky Med, are ideally suited for urban environments (Baghermanesh et al, 2022). Thermal sensors, such as the moderate-resolution imaging spectroradiometer (MODIS) and the advanced very high-resolution radiometer (AVHRR) series, can provide images of the earth's surface temperature, which can be used to detect the presence of flood water and monitor the evolution of floods over time (Colosio et al, 2022).…”

Environmental Monitoring: A Comprehensive Review on Optical Waveguide and Fiber-Based Sensors

“…Flooding may be an attribute of a complex of dangers during extreme weather events that also include mudslides, gales, and tidal surges and causes much more havoc. Floods are the worst form of danger since they often occur, have a wide-ranging impact on every region of the Earth, and are monster threats that do not simply happen once in a lifetime [ 7 ]. Low-magnitude, frequent floods can harm farmland, disrupt, or destroy buildings and infrastructure, stop business and other operations, expose people to health concerns, and so forth.…”