METHODS
I chose to examine the effects of this fire on the impacted
watersheds as seen in Figure 1. The land impacted by the fire is shown in red,
near the area labeled Los Alamos. This background map came from Assignment 2
which dealt with Pan Evaporation data. I used the county data in order to
create a vicinity map for the fire data. The fire data came from the Burned
Area Emergency Response (BAER) process through the US Forest Service. This data
was created specifically for soil analysis and was last updated in 2014.
Lastly, the digital elevation model (DEM) used for this analysis came from the
US Geological Survey (USGS) from the National Map. It is a 1/3 arc-second DEM,
which is approximately 10m by 10m. This data was all analyzed using ArcGIS
10.6.1.
Since this analysis involves New Mexico alone, the
maps are all projected using NAD 1983, UTM Zone 13N so that New Mexico is
centered on the map. This projection method minimizes area distortion and distance
distortion which are both important for the stream length analysis. Using the
same projection for all data makes it possible to overlay layers and compare
distances, or shapes without distortion.
The fire data categorized the severity of the Las
Conchas fire into three categories, determined by the loss of organic matter in
the soil (Keeley, 2009). This analysis was done by BAER using remote sensing
to determine the amount of organic matter remaining post-burn. These categories
are shown in Figure 2, with the darkest color representing the highest severity
class. Some areas of the fire were unchanged, and these areas were left out of
the analysis.
A watershed was established using the DEM taken from
the National Map from the USGS website and the hydrology toolset from ArcToolbox. A model of the steps taken to determine the
streams and watershed is shown to the left in Figure 3. New layers were created
from each fire severity class in order to overlay the stream layer with the
different categories of burn areas. The length of impacted stream for each
category was determined using raster calculator with these individual layers
(Figure 4).