4.2.1 Massive Ice Model Validation
HWR from 2017 to 2018 provides a means of validating the accuracy of the MI model by comparing the modelled ice surface elevation with the resultant 2018 headwall exposures. The trends in IT and OT exposed in the headwalls from 2016 to 2017 can be seen in Figure 9. The IT increased and OT decreased in the middle and western segments, while the opposite trend occurred in the east. The MI elevation model predicts a continuation of a high elevation MI and thin OT in the middle and a reduction in IT and OT in the east. Ice in the west is modelled to dip steeply inland with a large reduction in the PI, counter to the 2016-2017 trend. 2018 in Figure 9 provides a comparison between the predicted MI surface (white dashed line) and the actual MI surface. The model accurately predicted the inland ice surface elevation pattern, with a maximum observed difference of just 1.4 m. The western segment was modelled to dip by between 2° and 18° from the 2017 position but, based on the resultant headwall exposures (and lack thereof), the actual angles are estimated to have been between 10° and 30°. Some ice may have been buried under mud just behind the headwalls and, where the ice is below the base of the headwall, its elevation cannot be determined from visual observations. These factors may have increased the difference in observed and modelled ice elevation.