On Mon, May 4, 2015 at 9:33 AM, Pat Tressel <ptres...@myuw.net> wrote:
> ;-) > > I'm seeing some rivers mapped in areas that didn't have high-res imagery, > that (in the DG imagery) cross over dry land, or through areas were tree > tops are visible against a dark background that could be either water or > shadow -- it's a dark gray-purple. What I'm interpreting as the actual > river channel is more turquoise and has (what look like) white rapids. The > imagery has no clouds, and land looks fairly dry, so this imagery may, > perhaps, be dry season. > > Note the previously mapped rivers in this area are very rough -- points > are far apart -- which implies they were mapped from low-res imagery. > > Some questions: > > Is there a large change in water volume in rivers during the dry season? > I'm wondering if water recedes to the deepest channel, and does show more > whitewater then. > Yes, changes in water volumes between wet and dry season can be immense in Nepal. Some stream beds may also go dry in the dry season. I would guess that some mountain streams may behave as you suggested, but generally, my expectation would be for more whitewater in the wet season. > > Do trees grow in standing water (deep enough to appear dark) in Nepal? > That's not unheard of -- it's true in the Everglades in Florida. Or is an > area with treetops and dark between more likely dry but shadowed? > Generally, most of the water in Nepal flows fast (we have lots of elevation changes), and there are very rarely trees growing in standing/moving water as in Florida. I don't understand your second question. > Thanks! > > -- Pat > > _______________________________________________ > HOT mailing list > HOT@openstreetmap.org > https://lists.openstreetmap.org/listinfo/hot > > -- Prabhas Pokharel http://prabhasp.com twitter/skype/facebook/whatever: prabhasp
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