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We are trying to help the county health department make a map of radon exposure at houses throughout the county. We are using ArcMap 10.1 with all extensions. They sent us an excel spread sheet with 3 relevant fields: (1) lat & (2) long in decimal degrees and (3) exposure concentrations. We want to convert the data in the table to points, then symbolize by the concentration. So far we have been able to get points in ArcMap by using the 'Display x y data' button but when we bring in the county map, the dots are far away from the county. Also, this resulting set of points has no attribute table to symbolize from. Is there a straightforward way to take data from an excel table and give it functionality in ArcMap? Thanks for reading.
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12-12-2014
03:32 PM
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George: I was able to add 2010 FEMA BFEs and XS lines to the map. I will try some of the interpolation tools. Thanks again. - Jerome
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05-09-2014
11:34 AM
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George: We are using FEMA 2007 BFE Data. I'm a student getting my GIS certificate interning with a county Office of Emergency Management in SW Colorado. The office is interested in this information in order to be prepared for a flood event similar to what struck Boulder, CO last September. The data I described is the only data I have been provided so I am not familiar with S_XS lines (are these the BFE lines before being rasterized? They are 1 ft. incremental cross section surveys that have length equal to the width of the floodway). I searched ArcGIS tools, did a google search, an ArcGIS help search, and did not return anything useful so I am assuming this is georeferenced surveying data. I will find out if this information is available to me. Also, unfortunately I am not familiar with Non-regulatory products (again, my searches for information were inconclusive). Since the BFEs are only 1 ft. in elevation apart and follow the floodway, it should be easy to estimate the elevations of the cells in between the BFEs (or so I thought). Once the rasters are in order, we will use the Multi Values to Points tool to associate the addresses in the floodway with the ground elevation of that point and the BFE elevation of that point. Then add a new field in the attribute table being the difference between the ground elevation and the BFE. The address points will be symbolized by this difference field, the addresses with the lower differences being in the most danger if we experience a flood event. This data can then be shared on ArcGIS online and other mediums so that it is available to emergency responders and they have a solid idea of where people may be at risk. Thanks for the response, - JB
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05-07-2014
12:19 PM
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Thanks for taking the time to review this post ;] Running: 10.2 with all extensions Problem: How to get a raster based on features to cover the floodway zone We are creating a flood hazard map in the following way: Take FEMA's flood hazard polygons and create a shapefile of the 100 year floodway zone Take the address points of residences in the county and clip to that floodway zone Take contour lines from the city and county and join them, then clip to the floodway zone Rasterize these contours (topo to raster). This is a digital elevation model of the actual terrain in the floodway zone. Take FEMA's base flood elevation polylines and rasterize based on elevation (feature to raster). This is a digital elevation model of FEMA's estimates of the elevation of the water surface during a 100 year flood event. *(This is the problem) Then simply use Multi Values to Points to add the fields for the elevation of the address and the elevation of the water surface during a flood. Create a difference field in the attribute table to be symbolized on the map (the lower the difference between the elevation of the address point and the elevation of the BFE, the greater the flood danger. The BFE lines when rasterized do not fill the entire floodway zone like the raster based on the contours (because the contours were clipped to the floodway, then rasterized). The BFE lines are only 1 ft in elevation apart so any data cells between the two lines should be easy to estimate, but in terms of latitude and longitude, they are up to 1/8 mile apart. Simply increasing the cell size leads to unacceptable estimation. Since we cannot capture all of the addresses in the floodway, this model has limited value. Is there a way in ArcGIS to extrapolate the rasterized BFE lines to fill the same area as the floodway? BTW, we already tried extending the BFE lines (before rasterizing) with the extend lines tool but without success since some of the polylines have their axis in the middle of the stream channel and diverge (also, extending the lines before rasterization doesn't help fill the gaps between BFEs that are quite far in distance apart). The BFE's vary in length and distance apart but do not vary in that every BFE is 1 ft in elevation different than the next BFE up or down stream. We simply need to fill in the small amount of gaps in the BFE raster that don't cover the entire floodway area. Thanks again for reading!- JB
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05-02-2014
12:55 PM
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Thank you very much. I will start downloading a DEM and try this technique!
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04-04-2014
09:42 AM
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We are mapping flood hazard zones and I am wondering if anyone could help me with the following: We have an address points shapefile located within a FEMA flood zone- addresses only, not Lat/Long coords We have 5 ft. interval contour lines (we may be able to get lidar based 1 ft contours) We have the FEMA polylines which give base flood elevation estimates for a 100 year event We can obtain a DEM of the area if needed The final product of this project is to create a query or model which will add three new fields to the address points attribute table: 1. Elevation of the address point based on the contours (or DEM if necessary), 2. the FEMA flood elevation associated with that address point and 3. the difference between the two. The lower the difference between the flood elevation and the address elevation, the more at risk that address is (which can then be symbolized). The County Office of Emergency Management will use this model to assess which homes are at the greatest risk during flooding (and show FEMA the grant $ is being used properly). Any tips, pointers or suggestions which tools will be needed would be greatly appreciated. We will soon have access to the complete ArcInfo package and associated tool extensions.
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04-02-2014
12:16 PM
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We are mapping flood hazard zones and I am wondering if anyone could help me with the following: We have an address points shapefile located within a FEMA flood zone- addresses only, not Lat/Long coords We have 5 ft. interval contour lines (we may be able to get lidar based 1 ft contours) We have the FEMA polylines which give base flood elevation estimates for a 100 year event We can obtain a DEM of the area if needed The final product of this project is to create a query or model which will add three new fields to the address points attribute table: 1. Elevation of the address point based on the contours (or DEM if necessary), 2. the FEMA flood elevation associated with that address point and 3. the difference between the two. The lower the difference between the flood elevation and the address elevation, the more at risk that address is (which can then be symbolized). The County Office of Emergency Management will use this model to assess which homes are at the greatest risk during flooding (and show FEMA the grant $ is being used properly). Any tips, pointers or suggestions which tools will be needed would be greatly appreciated. We will soon have access to the complete ArcInfo package and associated tool extensions.
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04-02-2014
11:53 AM
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