Use of remote-sensing deformation monitoring for the assessment of levee section performance limit state

Performance monitoring of the Sacramento Delta levee system on the network level and the assessment of exceeding potential limit states are needed for the maintenance and rehabilitation of this system. In this case, deformation needs to be assessed especially in view of the levees age, sea level rise, and ongoing subsidence due to the decomposition of the peat foundation layer. The work presented herein describes the remote sensing of a levee section deformation with time, which will ultimately be used for levee condition assessment. The levee section is located on Sherman Island, California and monitoring was conducted in situ by GPS, in addition to remote sensing by airborne synthetic aperture radar. Coupled deformation/seepage numerical analysis of the levee section is performed using finite element modeling software. The numerical model included characterization of the unsaturated-saturated zones and the peat foundation layer. The numerical analyses were also used to assess the probability of exceeding a prescribed deformation limit state while varying the loading conditions in terms of rate of rising and duration of high water level in the reservoir.