/*

/* *************************************************************

/* USDA - ARS

/* Southwest Watershed Research Center

/* 2000 E. Allen Rd.

/* Tucson, AZ 85719

/* *************************************************************

/* Program: subws.aml

/*

/* Function: Automates the creation of subwatersheds within

/* a given watershed.

/*

/* History: Created 1997 by Scott Miller, USDA - ARS SWRC,

/* 2000 E. Allen Rd. Tucson, AZ 85719.

/* ph: 520-670-6380. miller@tucson.ars.ag.gov

/* *************************************************************

/* Routines called: none

/*

/* Requirements: flowaccumulation and flowdirection GRIDs

/*

/* Results: Creates a polygon map of the subwatershed

/* areas for the use of the ARDBSN model

/* *************************************************************

/* Usage: &r subws <watershed> <threshold>

/*

/* Arguments: threshold - # of cells that will be used to

/* determine where the streams are located.

/* *************************************************************

/*

&args size

&if [null %size%] &then &do

&type

&type Usage: &r subws <threshold>

&type

&return &inform

&end

&stat 9999

&if %:PROGRAM% ne GRID &then &do

&if %:PROGRAM% ne ARC &then quit

grid

&end

/* First go into GRID and create the stream network (and a polygon

/* coverage from that), then a preliminary subwatershed map based on the

/* intersections of the channels.

strm_%size% = con (dem6_acc > %size%, 1)

stream_%size% = streamline (strm_%size%, dem6_dir)

ppts_%size%a = streamlink (strm_%size%, dem6_dir)

sub_%size%a = watershed (dem6_dir, ppts_%size%a)

subws_%size%a = gridpoly (sub_%size%a)

q

/* Now use ArcEdit to select all the arcs and extract the tops of all

/* the channels. The reason to do this is that GRID's method (above)

/* does not create subwatersheds at the upland level, only for where

/* intersections take place. So we are getting the coordinates of where

/* the uplands start.

build stream_%size% node

ARCEDIT

&sv test = [show display]

EC stream_%size%

EDITFEATURE arc

/* First step is to select all the nodes that represent stream junctions

/* and export their x-, y-coordinates into usable format.

/* This is done in ArcEdit. Select all the tnodes in order. If no

/* arc is associated with a particular number, it should be selected,

/* since it is a terminal node.

ef node

&sv last [show maximum node]

ef arc

&sv num = 0

&sys touch nodes_%size%.txt

&label here

&sv num = %num% + 1

sel tnode# = %num%

&if %num% <> %last% &then &do

&sv sel = [show number select]

&if %sel% = 0 &then &sys echo [show node %num% coordinate] >> ~

nodes_%size%.txt

&goto here

&end

/* Get out of ArcEdit & create the file necessary to build a

/* subwatershed map in GRID, then go into GRID and do it.

quit

grid

/* Use the "snappour" procedure to ensure that we're in the lowest

/* point within 10m of the outlet.

ppts_%size%b = snappour (nodes_%size%.txt, dem6_acc, 10)

sub_%size%b = watershed (dem6_dir, ppts_%size%b)

subws_%size%b = gridpoly (sub_%size%b)

/* In Arc, append the 2 subwatershed maps together

quit

append subws_%size%

subws_%size%a

subws_%size%b

end

clean subws_%size%

createlabels subws_%size%

kill ppts_%size%a all

kill ppts_%size%b all

kill sub_%size%a all

kill sub_%size%b all

kill strm_%size% all

kill subws_%size%a all

kill subws_%size%b all

&return