MAPPING WEAKNESSES IN THE MISSISSIPPI RIVER LEVEE SYSTEM USING MULTI-TEMPORAL UAVSAR DATA

Resumo

Levees are extended embankments naturally or artificially constructed that regulate water levels. The Mississippi Levee system in USA dates from early 1900's, and was designed to keep farmlands safe during the flooding. Today it is considered one of the most extensive engineering infrastructure projects in the world. The Mississippi Levee system comprises over 5,600 km of earthen wall structure designed to protect the agricultural areas of the Mississippi River Valley, thus monitoring the physical condition of the levees is vital for flood control. The dynamics of subsurface water events cause continuous damage on levee structures which are not easily spotted prior to the appearance of slough slides or through-seepage. The traditional method used for detecting these events involves physical surveys, always time consuming and expensive. Synthetic Aperture Radar (SAR) technologies are capable of identifying variations in soil properties that are related to the potential for such events. This paper presents a compendium of methods and results of applying the NASA Unmanned Aerial Vehicle Synthetic Aperture Radar (UAVSAR) to the task of identifying problems on Mississippi's earthen levee system. UAVSAR is a multi-polarized SAR system, and the data exploration in this study included both single-look and multi-look records. The team investigated soil moisture, soil electrical conductivity, sand boils, landslide events, and vegetation backscatter. Different feature detection and classification algorithms were tested, including radiometric and textural methods. The levee structure and flood control system is managed by the United States Army Corps of Engineers (USACE), who would benefit from having a unified tool capable of mapping the weakness of the levee segments. The data and methods presented in this paper are incorporated into the Multi-Tabbed Levee Assessment Tool. The solution provides a user-friendly, open-source geospatial platform to perform visualization, manipulation and analysis of SAR data products.