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GIS Layers Inventory Comparing Levels of Risk Setbacks Down-Zoning and Land Acquisition Permit Issuance Indicators |
 LIDAR data are
being used, in conjunction with a GIS, to assess a beach's
vulnerability to erosion hazards. Oregon is moving towards
beach management through a littoral cell management approach
versus a site-specific approach. This section describes
several ArcView® project "views" that use the results of the
Dune Hazard Assessment Tool (DHAT) to demonstrate
potential effects on policy.
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GIS Layers Inventory
For any planning process that uses GIS as a tool, the first
step is to gather together all physical (topography, soils,
etc.) and cultural (tax lots, zoning, etc.) data layers so
that the impacts of environmental change on the structures and
development in an area can be assessed. This view shows a
combination of physical and cultural inventory layers for the
South Beach and Holiday Beach areas in South Newport, Lincoln
County, Oregon.
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Comparing Levels of Risk Using
DHAT, it is possible to create different scenarios of
potential erosion due to storms. Using these different
results, planners can then make the critical decision of
determining where development should occur. This view shows
the results of a risk assessment - extreme, high, and low
relative risk layers - for dune-backed shoreline along South
Beach in south Newport, Lincoln County, Oregon.
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Setbacks This view gives
an indication of the viability of potential hazard
avoidance measures. For example, it suggests that a
construction setback may be effective along the central
portion of the segment of shoreline depicted in the view.
This may not be the case for all the tax lots depicted in the
view, particularly those located in the southern portion.
Consideration may need to be given to other hazard avoidance
measures, such as zoning controls of land acquisition.
To get this information, a query was made to show vacant parcels in private ownership in a high-risk zone. Assuming that the landward boundary of the zone of high relative risk represents an oceanfront construction setback line, then it is readily apparent how many property owners (i.e. tax lots) are affected - 13. These results could be compared with an alternative, say a more conservative setback defined by the zone of low relative risk, to determine if significantly more tax lots are affected and in turn if a more conservative setback might be politically acceptable. |
Down-Zoning and Land Acquisition
This view shows the results of the same query along a
different segment of shoreline. It is readily apparent that a
construction setback is unlikely to be effective. However, a
review of additional attribute information contained within
the view suggests that other hazard avoidance measures may be
viable. For example, an examination of the zoning designation
of the affected lots indicates that the lots are zoned medium
density residential and high density residential.
Consideration may be given to down-zoning as a means of
reducing risk. An examination of the ownership of adjacent
lots indicates that many are in public ownership. Land
acquisition may be a viable, if not the preferred, alternative
in this instance.
By moving along segments of shoreline within a littoral cell and conducting the types of analyses illustrated above, a suite of preferred hazard avoidance measures can be identified for various segments of shoreline. When taken together they constitute a hazard avoidance strategy for a given littoral cell. |
Permit Issuance Indicators
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Both of these views show the results of a query for the following criteria:
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