Introduction My interests are related to engineering aspects of Bald Head Island. Bald Head Island is a small community facing several development related issues that have potential impacts on island property values. Two significant issues include oceanfront setbacks and a proposed inlet hazard area at the mouth of the Cape Fear River. Problem Statement Inlet hazard areas and erosion setback areas as defined by state policy affect property value, and thus tax revenue. For civil planning purposes, it would be helpful to understand how new policies proposed by the state will affect the local tax base. Analysis of policy impacts may be useful in determining a strategy for adapting to policy changes, or refuting them if necessary. A potential metric for determining the importance of land use planning policy on a specific site such as Bald Head Island is to determine the value of property affected by the policy. To gauge the relative importance of the proposed inlet hazard area to village homeowners, this exercise seeks to compare the value of property affected by hazard area changes to the value of property impacted by oceanfront setback rules. Current oceanfront setback rules for NC state that single family residences, regardless of size, must be set back from the first line of stable natural vegetation a distance of 30 times the long-term average annual erosion rate ( HYPERLINK "http://dcm2.enr.state.nc.us/setbacks.htm" http://dcm2.enr.state.nc.us/setbacks.htm ), and a minimum of 60 ft. Inlet Hazard areas, last delineated in 1979, are currently undergoing revision by NC DENR Division of Coastal Management. Revision of these areas is based on historical shoreline position, as extracted from historical photos, near inlets. ( HYPERLINK "http://gsa.confex.com/gsa/2007SE/finalprogram/abstract_119320.htm" http://gsa.confex.com/gsa/2007SE/finalprogram/abstract_119320.htm ) Expected Data Requirements From Brunswick County Bald Head Island property parcels (vector polygon) ? describes property boundaries and attributed property value. BaldHeadIsland.gdb, including parcel boundaries and related property owner table. Cyndi Hendricks w/Brunswick County, by ftp transfer. From NCDENR Division of Coastal management Static vegetation line (vector polyline) ? basis for determining setback line. Staticveg_BaldHead_line_20100108.shp State published erosion rates (vector points) ? this is an input to the setback equation. 2004_ER_Points.shp ? official erosion rates published by DCM. Current inlet hazard areas (vector polygon) ? describes area currently defined as inlet hazard. IHA.shp Proposed inlet hazard area (vector polygon) ? describes new inlet hazard areas. Proposed_IHA_01132009_poly.shp HYPERLINK "http://dcm2.enr.state.nc.us/Maps/chdownload.htm" http://dcm2.enr.state.nc.us/Maps/chdownload.htm Analysis Questions 1. What is the area within the setback zone for Bald Head Island, based on the NCDENR erosion rate points and the static vegetation line? 2. What is the value of property of affected by the setback zone? 3. What is the value of property affected by inlet hazard areas changes, and which impacts a greater property value? Analysis Plan ? Determine selected sets - Some available data is statewide (i.e. erosion rates), while some is specific to Bald Head Island. Data of interest must be extracted from the larger sets. Use a spatial join to associate erosion rates with static vegetation lines. It will be required to add a field for setback distance to the spatially joined vegetation lines. This value will be calculated as 30 x the erosion rate. According to DCM policy, erosion rates less than 2 will be replaced by 2 to arrive at the minimum setback distance of 60 ft. Using the appropriate buffer options, a shoreward (left) buffer will be applied to the static vegetation lines based on the setback distance field. The output is the setback area. Summarizing area for this polygon answers Question 1. The output of Question 1 will be intersected with the city parcels. The output polygon represents parcels impacted by setback rules. Summarizing value of these properties answers Question 2. The proposed inlet hazard area will be clipped by the existing inlet hazard area polygon. The resulting polygon is the change in inlet hazard area. This polygon will be intersected with city parcels. The resulting polygon will represent the properties affected by changes to the inlet hazard area. The total value of these properties will be determined and compared to the answer from Question 2 to determine the answer to Question 3. Expected Outcomes ? Expected outcomes include a setback buffer based on the static vegetation line and published erosion rates, a polygon representing the increased area within the proposed inlet hazard area, and values of property impacted by erosion setbacks and inlet hazard areas.
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