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Methodology and Interpretation
RHUM120 - Percent all human land use within 120 meters of streams
The percentage of human use land cover 120 meters adjacent to streams is
calculated by summing the total number of agricultural, urban and non-natural
barren (transitional and mines/quarries) land cover cells underneath stream
segments in the 3 km grid cell reporting unit and within a three cell buffer
(120 meters) and dividing by the stream corridor's total land area (all cells
120 meters adjacent to streams minus those classified as water). Cells inside the
buffer zone but outside of the grid cell boundary are ignored. This metric can be
used to identify areas near streams which may be more susceptible to non-point source
pollution, pesticides, excess fertilizer and soil erosion which may result in
stream and lake sedimentation or eutrophication.
Quantile: Each class contains an approximately equal number (count) of features. A quantile
classification is well-suited to linearly distributed data. Because features are grouped by the number
within each class, the resulting map can be misleading, in that similar features can be separated into
adjacent classes, or features with widely different values can be lumped into the same class. This
distortion can be minimized by increasing the number of classes.
Natural Breaks: Classes are based on natural groupings of data values. Natural break points
are identified by looking for groupings and patterns inherent in the data. The features are divided
into classes whose boundaries are set where there are relatively large jumps in the distribution of
data values.
* EMAP-West Landscape Metrics Metadata (FGDC)
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