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Messages - Ila Chawla

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Models / Re: Anybody working with VIC model
« on: June 16, 2016, 02:46:27 PM »
I would like to add some more information to this post. From personal communication with Sat I could learn the manner in which flow direction map should be prepared and I would like to summarize the findings here.

Once the flow direction map is prepared, though a tedious job in case of huge basins, one has to visualize how the flow is taking place from one cell to other. Say I have following 3 by 3 cells encompassing my basin.
1 1 0
1 1 0
0 0 1
where, 1 indicates locations where basin is situated and cell(3,3) is the outlet (indicating all the water in basin should drain to this cell). Let us assume we got following flow direction map.
5 7 0
5 1 0
0 0 1
where, the numbers indicate the directions provided in http://vic.readthedocs.io/en/vic.4.2.c/Documentation/Routing/FlowDirection/

If you observe cell(2,1) the flow direction, which is 5, is showing that the water is flowing outwards (south direction). And cell(2,2) has north direction. It can be observed that these numbers will form an eternal loop of water flow without it ever reaching cell(3,3). This could lead to an error while executing routing model, more specifically, "Searching for catchment" issue.
I would expect the cell(2,1)'s direction to be 3 (towards east) and cell(2,2)'s direction to be 4 (south-east towards cell (3,3)) which gives the following flow direction file.
5 7 0
3 4 0
0 0 1

Now if we visualize the flow of water from cell to cell, we can observe that water from all the cells finally reaches cell(3,3). Thank you Sat for helping me understand this very sensible concept.
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