Eric Senecal Assignment 8 – Project Flow My project has changed again significantly, but emerged from considering criteria for my buildable lands project in Portland, ME. No parcel data was available and it was difficult to settle on criteria. One aspect of that analysis that I was interested in was coastal flood hazards considering the predicted increase in storm intensities and rise in sea level. I decided to shift back to Massachusetts and to do a coastal risk assessment of two towns on Salem Sound, Danvers and Salem. The goal of this project is to analyze certain coastal flooding risks that Salem and Danvers are facing and determine which is at greater risk based on property and human exposure to flood hazards. Recent years have seen serious flooding on the north shore in the towns of Wakefield and Peabody. Predictions for 30% increase in rainfall in this century due to climate change are common. At a recent Tufts panel on local effects of climate change, the current 100-year flood level was described as being approximately a 4-year event when sea level rise due to subsidence, thermal expansion, and assimilation of continental ice, along with the increased intensity and frequency of hurricane surges are accounted for. This project takes a simple approach to comparing the flood risk to exposed parcels and facilities in each town, and the demographic differences between towns as a way of beginning to compare vulnerability of different communities to more severe weather events. Project Steps Add all layers in 2 data frames (one for each town) Re-categorize land use, and perform queries, editing, and intersects for each town Figure out how to analyze connectivity of road network if not too difficult Create estimate of population affected based on block group data (I thought simple population data was available at the block level. MassGIS has a block table but it gets added under my block group layer in the source view and cannot be joined to the block layer) Calculate areas and percentages of flooded parcels by land use Create tables, large scale detail area maps, and explanatory text for poster Finalize maps for poster Create poster layout Data Processing Steps Select Danvers and Salem interactively out of Town Boundary layer Add parcel, land use, and demography data at the block group level. Add and join block group tables for household income, population and age Select land use polygons and parcels that are within or intersect the town Add Q3Flood layer – adding 5 flood zone categories including 500-year flood as an estimate of what may become a decadal scale event. Select Flood polygons that intersect the town Add EOT roads layer Add schools point data Edit the Land Use 21 layer into broader categories by adding a new field, using the editor toolbar, and selecting by attributes. Adjust symbology. Residential Commercial Open Space Recreational Facilities Woods and Brush Fresh Water Industrial Buildable vacant land Ag Lands Union of Land Use and Parcels Select by location new parcels that intersect flood polygons, or perform intersect. Select by attribute for different land use parcels and calculate area of each land use in flood zone, number of parcels of each use, estimate of people in flood parcels based on population and percent of total population flooded. Possibly analyze road network flooded by total miles flooded and subsequent reduced connectivity of existing non-flooded roads. Look at most flooded block groups by age and income Do the same for both towns This project will utilize the querying capacity of GIS, selecting by location and by attribute, both in creating new selections and from current selections. I will use the editor tool bar to populate a new parcel and land use field called landuse so that the 21 uses can be categorized. I may use the intersect tool or clip tool, or may select by location to select flooded parcels depending on which is more feasible. I will calculate geometry of flooded land use parcels in a new field, probably in acres. I do not yet know the GIS technique for analyzing connectivity of streets. This project will result in a map of Danvers and a map of Salem that clearly show the parcels at risk of potential flooding, symbolized by land use characteristics. Each map will have an accompanying table detailing the total area and percent area flooded by land use, the number of parcels and estimate of people affected, the reduced connectivity of roads due to flooding, the percent of current “buildable vacant land” that would be flooded and should not be built on, the number of schools affected, and a simple demographic comparison of the two towns. In addition to the town maps, I will include large scale maps of critically affected areas for each town. A discussion of the findings and limitations of this simple analysis will be included on the poster, as well as an overview my thoughts on the need for coastal risk assessment with changes in the frequency of 100 year flood being predicted. I will also summarize the results to show that two nearby towns may face different risks, and demonstrate that GIS can be a powerful tool in analyzing those risks, potentially much more completely.