Correction to “Hydrologic and geomorphic controls on hyporheic exchange during baseflow recession in a headwater mountain stream”

[1] In the paper “Hydrologic and geomorphic controls on hyporheic exchange during baseflow recession in a headwater mountain stream” by Adam S. Ward et al. (Water Resources Research, 48, W04513, doi:10.1029/2011WR011461, 2012), the inverse modeling of electrical geophysical data is described in section 2.4.2 as follows: “Data collected during and after the tracer injection were inverted using the background model as a starting model. Thus, each time step was inverted independently [as by Ward et al., 2010, 2012]. Time lapse-inversion [e.g.,LaBrecque and Yang, 2001], or inversion of differences might provide some improvement in the results and should be considered for future studies.” This description is incorrect. The results presented do use the background (pretracer) model as a starting model, as stated, but the inversion used was the difference inversion of LaBrecque and Yang [2001]. Briefly, this is a modified version of the Occam's inverse method where the inversion seeks the change in subsurface model parameters from the starting model by inverting on the change in observed electrical data, conditioned on a reference model parameter set (in this case, the pretracer model). These inversion techniques were selected to reduce artifacts in the time lapse images and to minimize systematic errors in the inversion models (e.g., errors arising from electrode configuration and model discretization).