Coastal Subsidence Study 2005 - Laserfiche WebLink

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In the DLNR report, it was proposed to specifically change the definition of the shoreline to add the term run-up and exclude gravity flow. When a bill was submitted to change the definition, controversy prevented its passage. However, with the existing definition of the shoreline, the case can be made that the State and counties can already, under their existing discretion, exclude gravity flow. During the shoreline certification process there is much discretion, and the State Surveyor looks at much evidence including the vegetation line and debris lines to determine the “upper reach of the wash of the waves.” The surveyor is to determine the upper reach of the wash of the waves, and this implies that the limit of the force of a wave, or the limit of wave wash or runup will determine the shoreline. Examination of Waiopae Road during maximum flooding events, such as at high tide, will allow the surveyor to identify where water flow is by wave runup (to be included) and not gravity flow downhill. So given reasonable discretion in the interpretation of the existing shoreline definition, gravity flow can be excluded. Although there may not be a need to modify the shoreline definition to exclude gravity flow, given the recent Supreme Court decision, it may make the State surveyor more hesitant to exclude gravity flow without changes in the definitions as described above. Given the current sensitivity with the shoreline definition, changing the definition in the State statutes would be hard to do. The definition could be changed in the rules at the State level and the county level, but this would also be difficult because of the issue, whether warranted or not, about the consistency with the controlling State statute. Nevertheless gravity flow, could be considered in the shoreline determination because supposedly debris lines would be caused by the upper reach of the wash of the waves, or run-up, while gravity flow would leave evidence looking different (e.g., no debris lines). From comments received by the State Surveyor’s office, Department of Accounting and General Services, gravity flow could possibly be excluded and is characterized where water is flowing downhill at an elevation above sea-level. For example in the case where wave washes up a beach face, overtops the dune and the water flows downhill by gravity, the portion flowing down hill could conceivably be excluded as evidence of the shoreline. Conversely, runup (water rushing up the slope of a beach) or current (water moving downhill because the bathymetry is below sea level) should be included in the location of the shoreline. In our observations of the water flow at Kapoho, it appears that in a few places along the mauka edge of Waiopae Road, water is flowing by gravity flow as opposed to runup or current flow. However it is not always possible to determine along the entire length of the road if the water is flowing mauka because of spillage and gravity flow or run-up and currents. Generally for the larger breach and channel in Figures 3-7 to 3-9, the water is flowing by run-up or current, whereas for the smaller and shallower channels, gravity flow may play a role in the extent of inundation. Thus, in a few locations, such as near the intersection of Waiopae and Kaheka, where flood 34