Mod 2: Lahars

This week in Applications of GIS we learned terms associated with disaster management:  natural hazard, risk, and mitigation.  We identified some strategies to utilize GIS to help manage hazards.  We looked at ways GIS is utilized to identify areas of concern and areas of public concern.  We identified features at risk during a lahar event (population, schools, infrastructure).  We mosaicked two Digital Elevation Models (DEM) to obtain a single layer.  We predict possible inundation zones from a lahar event from Mount Hood in Oregon.  We created the point for Mount Hood utilizing the XY tool and converted it to a graphic feature.  Predictions were made by utilizing ArcMap spatial analyst Hydrology tools on DEM to create a Fill raster to remove small imperfections, Flow raster to represent the direction across each cell, and Flow Accumulation raster to show which cells receive the most flow.  We utilized Raster Math to change the raster from float point data (continuous) to integer data, calculated 1% of total pixels to perform Stream Classification, Con Tool to limit the stream calculation to greater than 1% of the total pixels and finally hydrology tool Stream to Feature to obtain a polyline vector feature to utilize in the Lahar's Analysis map from above.  Census block groups were selected that intersected a 1/2 mile buffered Stream that allowed for population in those block groups.  Locations of schools within the 1/2 mile buffered Stream were also mapped.