Monitoring High-Water Conditions Using Nighttime Thermal Imagery

High-water conditions have been traditionally monitored from images registered during the daytime in the visible and near-IR bands. However, a number of factors may be at work that hinder reliable discrimination of high waters on daytime imagery. These factors include: specular reflection from the water, and the presence of semi-submerged ice and wet soil, each having reflectances similar to water. It is shown that night-time thermal images can be employed, on which only the natural emission of water and natural features is registered, in the reliable detection of flood waters (nighttime brightness temperature of water is higher).