/* STREAMLINESHED.AML
/* Author: Jacek Blaszczynski 03/11/99 Original Coding
/*
/*
/*------------------------------------------------------------------------------
/*
/* This AML delineates watersheds for watershed outlets located at 
/* junctions and sources of a stream coverage. The program first creates basic
/* hydrologic terrain analysis grid layers of a filled DEM ("filled"),
/* flowdirection map for the filled DEM ("flowdirz" - the "z" suffix
/* indicates the operation was performed on a filled DEM), and a 
/* flowaccumulation map ("flowcountz").  Then it uses a line vector stream
/* map to identify the endpoints and points of intersection (nodes) of stream 
/* lines and make them into a point coverage.
/* The point coverage is then rasterized to serve as outlets for watershed
/* delineation.  "SNAPPOUR" function is used to locate the streams
/* in high flow accumulation areas (channels) modeled from the DEM
/* within user specified distance in number of cells. Then the GRID "watershed" 
/* function calculates the watershed areas based on the outlets and the flow 
/* direction map.  
/* 
/*-----------------------------------------------------------------------------
&severity &error &routine bailout
&args source_dem in_streams out_sheds snap_dist

/* Check arguments
&call chkargs

/* Do the work
&call main

&call exit
&return /* End of streamlineshed.aml

/*--------------
&routine chkargs
/*--------------
&if [SHOW PROGRAM] <> GRID &then &do
  &type This aml must be run from GRID.
  &call bailout
&end
&do arg &list source_dem in_streams out_sheds snap_dist
  &if [NULL [VALUE %arg%]] &then &do
    &call usage
    &call bailout
  &end
&end
&if not [EXISTS %source_dem% -GRID] &then &do
  &type Input grid: %source_dem%, does not exist.
  &call bailout
&end
  &if [LENGTH %source_dem%] > 13 &then &do
    &type Grid names must be 13 characters or less.
    &call bailout
  &end
&if not [EXISTS %in_streams% -COVER] &then &do
  &type Input cover: %in_streams%, does not exist.
  &call bailout
&end
&if [EXISTS %out_sheds% -GRID] &then &do
  &type Output grid: %out_sheds% already exists.
  &call bailout
&end
  &if [LENGTH %out_sheds%] > 13 &then &do
    &type Grid names must be 13 characters or less.
    &call bailout
  &end

&return /* End of routine chkarg


/*-----------------
&routine thresh_error
/*-----------------
&type Flow threshold values must be an integer or real value less than or equal to 100,000 cells
&return /* End of routine thresh_error


/*------------------
&routine main
/*------------------


/*----------------------------------------
/* Set the display environment and
/* prepare hydrologic terrain analysis
/* data sets.
/*----------------------------------------

&echo &brief
&TERMINAL 9999
DISPLAY 9999 2 position cr
setwindow %source_dem% %source_dem%
mape %source_dem%
gridpaint %source_dem% value linear wrap gray

&if [EXISTS shedoutlets -GRID] &then &do
  kill shedoutlets all
&end
&if not [EXISTS filled -GRID] &then &do 
  fill %source_dem% filled
&end
&if not [EXISTS flowdirz -GRID] &then &do 
  flowdirz = flowdirection (filled)
&end
&if not [EXISTS flowcountz -GRID] &then &do
  flowcountz = flowaccumulation (flowdirz)
&end

gridnodatasymbol transparent
markercolor 7
linesize .025

/*--------------------------------------------------------
/* Create a map of outlet points from the stream coverage
/*--------------------------------------------------------

arc nodepoint %in_streams% streamnodes
points streamnodes
setcell %source_dem%
setwindow %source_dem% %source_dem%
shedoutl = pointgrid (streamnodes)
kill streamnodes all
shedoutlets = snappour (shedoutl, flowcountz, %snap_dist%)
%out_sheds% = watershed (flowdirz, shedoutl)
kill shedoutl all
gridshades %out_sheds%
arcs %in_streams%
&echo &off

&return /* end of routine main
/*
/*------------
&routine usage
/*------------
&type Usage: &r streamlineshed <in_elev_grid> <in_stream_cover> <out_watersheds> <snap_distance>
&type RUN POLYGONSHEDS.AML TO CREATE A POLYGONAL WATERSHED COVERAGE !!!
&return /* End of routine usage

/*-----------
&routine exit
/*-----------
&do grd &list editshed mskgrd
  &if [VARIABLE %grd%] &then &do
    &if [EXISTS [VALUE %grd%] -GRID] &then &do
      KILL [VALUE %grd%] ALL
    &end
  &end
&end
&return /* End of routine "exit"

/*--------------
&routine bailout
/*--------------
&severity &error &ignore
&call exit
&return &error Bailing out of streamlineshed.aml...