A Method to Quantify Seepage Impact on River Bank Erosion.

Seepage has gained significant recognition as an important mechanism of river bank failure.  Yet, methods to identify the location and quantify the impacts of seepage induced river bank erosion across large scales are lacking.  The objective of this study was to assess if laser intensity returns from terrestrial and airborne light detection and ranging (lidar) could be used to detect seepage locations on river banks and if these seepage locations relate to the extent of bank erosion calculated from multi-temporal lidar change detection.  We tested the above concept in South-central Minnesota on two separate river banks with terrestrial lidar acquired in 2012, 2013, 2014 and 2015.  The results indicate that both terrestrial and airborne lidar intensity returns provide a means to identify the location of seepage on river banks and, in combination with lidar measured elevation change, provides a means to quantify seepage induced bank erosion.