[GRASS-user] Measuring Stream Lengths

Rich Shepard rshepard at appl-ecosys.com
Sat Jan 30 19:06:44 EST 2010

On Sat, 30 Jan 2010, Dylan Beaudette wrote:

> Where did these data come from? It sounds like they were generated outside
> of GRASS. Can you describe the structure of this 'streams' dataset, and
> possibly how it was made?


   They're from the Oregon Geospatial Data Center. The state works strictly
with ESRI products under windoze. I'll send you the metadata pdf if you want

> 1. segments with cat numbers, see v.category
> 2. an attribute table attached to this vector
> 3. stream names (?) populated in one of the columns, possibly with
> v.digit, or v.what
> 4. create a new column for the segment lengths
> 5. populate this column, v.to.db

   Here's the top of lotic.sql which I used to populate the SQLite table:

PRAGMA foreign_keys=OFF;
   llid  TEXT,
   name TEXT,
   gnisNum TEXT
INSERT INTO "lotic" VALUES('1173558419005','','0');
INSERT INTO "lotic" VALUES('1173558419012','','0');
INSERT INTO "lotic" VALUES('1173593419067','','0');
INSERT INTO "lotic" VALUES('1173594419068','','0');
INSERT INTO "lotic" VALUES('1173804418848','','0');
INSERT INTO "lotic" VALUES('1173809419594','','0');
INSERT INTO "lotic" VALUES('1173817419323','','0');
INSERT INTO "lotic" VALUES('1173850419296','','0');
INSERT INTO "lotic" VALUES('1173857419343','','0');
INSERT INTO "lotic" VALUES('1174094419475','','0');
INSERT INTO "lotic" VALUES('1174103419484','','0');
INSERT INTO "lotic" VALUES('1175170420086','Rock Creek','1135566');
INSERT INTO "lotic" VALUES('1175178419964','','0');

   The 'llid' column is the lat/long of the head of each reach. There is one
additional column with another ID number that I did not import because it's
redundant to the gnisNum.

   Not much to work with, but I suppose that most folks who use these data do
digital cartography more than spatial analyses.


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