# A Review of Cutting-Edge Sensor Technologies for Improved Flood Monitoring and Damage Assessment
## 3 Overview of Flood Sensor Development
### Flood Satellite Remote Sensing Sensors
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**Sensor** & **Measuring Range** & **Advantages** & **Disadvantages** \\ \hline \multirow{3}{*}{Multispectral Sensors} & \multirow{3}{*}{Meter level} & 1. High spatial resolution & 1. Affected by clouds and atmosphere \\  & & 2. Multispectral & 2. Not real-time \\  & & 3. Recognition of surface & 3. Unsuitable for measuring \\  & & cover types & small-scale floods \\ \hline \multirow{3}{*}{Hyperspectral Sensors} & \multirow{3}{*}{Meter level} & 1. High-resolution & 1. High costs \\  & & 2. Accurately identify & 2. High volume of data \\  & & surface changes & 3. Complex data processing \\ \hline \multirow{3}{*}{Ultra-spectral Sensors} & \multirow{3}{*}{Meter level} & 1. Extremely high-resolution & 1. High costs \\  & & 2. Detectable weak changes & 2. High technical requirements \\ \hline \multirow{3}{*}{Near Infrared Sensors} & \multirow{3}{*}{Meter level} & 1. Can distinguish between & 1. Affected by clouds and atmosphere \\  & & water bodies and vegetation & 2. Requires atmospheric correction \\ \hline \multirow{3}{*}{Mid-infrared Sensors} & \multirow{3}{*}{Meter level} & 1. Can be used at night & 1. Affected by clouds and \\  & & 2. Sensitive to water and & atmospheric humidity \\  & & ground temperatures & 2. Low-resolution \\ \hline \multirow{3}{*}{Far Infrared Sensors} & \multirow{3}{*}{Meter level} & 1. Suitable for monitoring & 1. Accuracy is affected by \\  & & surface temperature and & the environment \\  & & atmospheric changes & 2. Requires atmospheric correction \\ \hline \multirow{3}{*}{Passive Microwave Radiometer} & \multirow{3}{*}{Meter level} & 1. Unaffected by light and \\  & & weather conditions & 1. High costs \\ \cline{1-1}  & & 2. Ability to penetrate clouds & 2. Accuracy affected by environment \\ \cline{1-1}  & & 3. High spatial and & 4. Unsuitable for high water content \\ \hline \multirow{3}{*}{On-board Advanced Synthetic Aperture Radar (ASAR)} & \multirow{3}{*}{Meter level} & 1. Suitable for all weather \\  & & conditions & 1. Low-resolution \\ \cline{1-1}  & & 2. Insensitive to terrain and & 2. Limited coverage \\ \hline \multirow{3}{*}{Radar Altimeter} & \multirow{3}{*}{Centimeter level} & 1. High-precision & 1. Affected by terrain \\ \cline{1-1}  & & 2. Suitable for measuring & 2. Limited application range \\ \cline{1-1}  & & changes in water surface height & 3. Unsuitable for dense vegetation \\ \hline \multirow{3}{*}{Interferometric Synthetic Aperture Radar (IfSAR) on Board} & \multirow{3}{*}{Sub-meter level} & 1. High-precision DEM & 1. High costs \\ \cline{1-1}  & & 2. Can recognise terrain changes & 2. Complicated data processing \\ \cline{1-1}  & & 3. Limitations in urban areas \\ \hline \multirow{3}{*}{Satellite-borne Synthetic Aperture Radar (SAR)} & \multirow{3}{*}{Sub-meter level} & 1. Can penetrate clouds and \\ \cline{1-1}  & & part of the vegetation & 1. High costs \\ \cline{1-1}  & & 3. Suitable for wide-area & 2. Complicated data processing \\ \hline \multirow{3}{*}{Satellite LiDAR} & \multirow{3}{*}{Sub-meter level} & 1. High-precision & 1. High costs \\ \cline{1-1}  & & 2. Accurate monitoring of & 2. Blocked by clouds \\ \cline{1-1}  & & terrain changes & 3. Unsuitable for large-scale mapping \\ \hline \end{tabular}
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Table 4: Advantage and disadvantage analysis of flood satellite remote sensing sensors. sensors to more advanced SAR and hyperspectral sensors. Nearly 50% of those satellites had been launched independently or with the participation of the United States. A number of countries in Europe had the capability to launch satellites, while in Asia, China and India had launched some of the relevant satellites. It was only in the past two years that China had launched its first commercial SAR satellites. \begin{table}
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