Due to Hurricane Irene, my esteemed university
cancelled the first day of classes on Monday, thus postponing the first session of the course I am teaching, the
GIS Practicum, until Wednesday. I thought I would use the time to generate a few slides showing the power of GIS during a crisis situation. I have quite a few family and friends in NYC and thus I was interested to see if they would be affected by the storm surge. What I found, after browsing three sources of storm surge data, were some massive inconsistencies. In one case in particular I felt the presence of poor storm surge data on the map was worse than having no data at all.
Let's start with Esri's
US Tropical Storm Map. I like it, because it includes precipitation data with the storm map and it worked fairly well on my Xoom. The storm surge data, however, just doesn't pass the snuff test. A single grid cell covers many square kilometers leading one to believe that their area, nearly 20km inland, could be subjected to a 9ft storm surge. From the Esri map you can basically tell that areas near the ocean are subject to storm surge. Not in the least bit helpful.
Compare this to the work Steven Romalewski and his
OASIS team put up. Clearly Steve and his team had access to localized, more authoritative data through the
NY State Emergency Management Office. Unlike the data Esri is displaying, the surge models actually makes sense when you compare them to topographic and hydrographic data sets. I could zoom into areas where my friends and family live and find out if they were likely to be affected. Would I trust the Esri map for that? No way!
Finally, the
National Hurricane Center has their map. The
Google Crisis Response Center map using the same underlying data (the graphic below is from Google). The data appear to be more detailed that what Esri is serving up, but the coarseness of the grid once gain results in some unrealistic patterns in which small section of the shoreline are excluded.
First, all of these organizations should be commended for taking the time to make this data available, but I do wonder, if in this case, Esri in particular is undermining their credibility by serving up data that is at its best, uninformative and confusing, and at its worst, wrong. I would be grateful to hear your thoughts on this matter, particularly if you happen to be a storm surge modeling guru.
