[GRASS-user] Interpreting r.watershed accumulation map

[Rich Shepard]

   The input to r.watershed (be_cropped) has elevation range of 148.2m -
168.4m. The accumulation output map has values ranging from
-89397.3-38013.4. An image of a portion of the map is attached.

   How do I interpret the colors on the map since the legend shows only a
narrow blue bar on a black background? As there are cells with high negative
values does this map contain any useful information?

   Given such flat land (the area in the image has an elevation difference of
approximately 1m) I have not identified a module that produces insights into
surface runoff patterns. I've tried several with no success; r.lake does
produce water depths based on the elevation of a blockage.

   Itzi does not work on these data because there are no stream channels for
use by r.water.outlet.

   Have I missed something?

Rich
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