r.answers(1)		      Grass User's Manual		  r.answers(1)



NNAAMMEE
       _r_._a_n_s_w_e_r_s  - Menu-driven interface from GRASS to ANSWERS

SSYYNNOOPPSSIISS
       rr..aannsswweerrss

DDEESSCCRRIIPPTTIIOONN
       rr..aannsswweerrss  integrates  ANSWERS  (1991) with GRASS.  ANSWERS (Areal Non-
       point Source Watershed Environmental Response Simulation) is  an  event
       oriented,  distributed  parameter  model that was developed to simulate
       the behavior of watersheds having agriculture  as  their  primary  land
       use.   Its  primary applications are watershed planning for erosion and
       sediment control on complex  watersheds,  and  water  quality  analysis
       associated with sediment associated chemicals.


       rr..aannsswweerrss  provides  a  menu of steps to complete the input required to
       run an ANSWERS simulation. Each simulation is treated as  "project"  by
       rr..aannsswweerrss.  The	inputs	collected for the steps completed are recorded
       under a project name, so that they may be copied or recalled  for  fur-
       ther  completion  or  modification.  The first menu one encounters when
       running rr..aannsswweerrss includes functions to create a new project,  work  on
       existing  projects,  copy  an  existing	project,  and  remove existing
       projects. The main menu (shown below) lists steps to  be  completed  to
       prepare	ANSWERS  input, to run ANSWERS, plus other miscellaneous func-
       tions.

	  ANSWERS on GRASS Project Manager Main Menu Project Name:
	  <_s_a_m_p_l_e>

	Status Option Description
       ---------------------------------------------------------
		 0    Quit
		 1    Set mask, region, and resolution
		 2    Catalogue soils parameters
		 3    Catalogue land use and surface parameters
		 4    Identify elevation-based input layers
		 5    Prepare rain gauge data
		 6    Identify outlet cell
		 7    Specify areas with subsurface drainage
		 8    Catalogue channel parameters
		 9    Define channel slopes
		10    Specify BMP's in watershed
		11    Prepare ANSWERS input and run simulation
		12    Miscellaneous Command Menu

	Option: 0__

       Steps 1-11 record and display their status to the left of the step num-
       ber.  If  a  step  has  not  been  run, no status is displayed (as seen
       above). If the step has been successfully completed, the status will be
       listed  as  "done".  In some cases, a change in one step will cause the
       need to run another step again, in which  case  the  status  will  read
       "rerun".  If  a	step  has  a status of "done" or "rerun", if it is run
       again it will attempt to offer previous inputs as defaults.


       IInntteerrffaaccee OOppeerraattiioonn NNootteess Throughout rr..aannsswweerrss  two  primary  types  of
       interface/input are used:



       1) Text input that can be completed by hitting the RETURN key.
	      In  most	cases,	if  no text was entered, the given question or
	      operation is canceled. Often times text input  will  consist  of
	      the name of a new or existing map or project name, in which case
	      entering the word "list" will provide a list of  currently  used
	      names.


       2)  Text  or  menu  options  that  can  be completed by hitting the ESC
       (escape) key. This type of interface is used for menus or for  entering
       tables  of  parameters. All menus have a default answer of Exit (0), so
       that by simply hitting ESC one may leave the program's menus. The  fol-
       lowing  keystroke  guide  is  helpful  to know when using the parameter
       entry worksheets that use this interface:

       <RETURN> moves the cursor to next prompt field
       <CTRL-K> moves the cursor to previous prompt field
       <CTRL-H> moves the cursor backward non-destructively within the field
       <CTRL-L> moves the cursor forward non-destructively within the field
       <CTRL-A> writes a copy of the screen to a file  named  "visual_ask"  in
       your home directory
       <CTRL-C> where indicated (on bottom line of screen) can be used to can-
       cel operation


DDeessccrriippttiioonn ooff MMaaiinn MMeennuu SStteeppss
       The following section describes each option  of	the  main  menu.   All
       steps  are verbose to provide as much immediate information as is prac-
       tical, however it is necessary that the user also be familiar with  the
       operation  of  ANSWERS.	(Obtain  a  copy  of the _A_N_S_W_E_R_S _U_s_e_r_'_s _M_a_n_u_a_l
       (1991) by David Beasley	and  Larry  Huggins.  Available  from  Bernard
       Engel, Agricultural Engineering, Purdue University, W. Lafayette, Indi-
       ana, 47907).


       Steps 1 through 10 collect  inputs  (either  maps  from	the  currently
       available mapsets or other text/numerical inputs) in order to create or
       extract the necessary portions of ANSWERS inputs for that  step.  After
       steps  1 through 10 are done, step 11 can be run to assemble an ANSWERS
       input file. ANSWERS can then be run using the inputs,  and  the	output
       from  the simulation is captured and processed, as described under step
       11.



       SStteepp 11 SSeett mmaasskk,, rreeggiioonn,, aanndd rreessoolluuttiioonn


       _M_a_p _i_n_p_u_t_: Watershed mask
       _O_t_h_e_r _i_n_p_u_t_s_: Project resolution, project region (optional)
       _D_e_s_c_r_i_p_t_i_o_n_: All raster values in the input mask map greater than  zero
       will  be  used  to  create reclass rules to set the project MASK to the
       watershed area. Each time the project is called, the MASK will be auto-
       matically set. Project resolution is input in meters and it used to set
       the size of the watershed elements to be used in  the  simulation.  The
       part of this step attempts to find the minimal region needed to contain
       the watershed mask at the given resolution.  A region  will  be	calcu-
       lated  to  allow  at least a one-cell border around the watershed area.
       This region is then presented in an input screen  (much	like  that  of
       rr..rreeggiioonn)  for  editing or approval. After the project mask, region and
       resolution are set, the information is recorded and will be reset auto-
       matically each time the project is called.  This step will create a new
       raster map in the user's current mapset enTITLEd _p_r_o_j_e_c_t _n_a_m_e>.ELEMENT.
       This  map  will	act  as a reference to ANSWERS' methods of refering to
       raster cells. Raster values of the map will  indicate  element  number,
       with the category description giving row and column numbers.  If any of
       the inputs in this step are subsequently reset, all  other  steps  that
       may  have been completed will be marked with a status of "rerun", since
       changing mask, resolution or region will require that inputs will  have
       to be resampled.



       SStteepp 22 CCaattaalloogguuee ssooiillss ppaarraammeetteerrss


       _M_a_p _i_n_p_u_t_: Soils
       _O_t_h_e_r  _i_n_p_u_t_:  Soils parameters, tile drainage coefficient, groundwater
       release fraction.
       _D_e_s_c_r_i_p_t_i_o_n_: This step prompts for the name of a soil map,  then  reads
       the  map and lists all soil categories found in the watershed mask. For
       each soil found in the  watershed,  ANSWERS  requires  values  for  the
       parameters  listed  below.  The Project Manager facilitates preparation
       parameters by input into a table.



       +------------------------------------------------------------------------+
       |Soil  Parameters  for  ANSWERS	(see  ANSWERS  Users  Manual  for more
       details) |
       +------------------------------------------------------------------------+
       |1	 total	 porosity   (percent   pore   space  volume  of  soil)
       |
       |2	      field	   capacity	   (percent	   saturation)
       |
       |3	    steady	state	   infiltration     rate     (mm/hour)
       |
       |4	difference  between  steady  state  and  maximum  infiltration
       |
       |				rate			     (mm/hour)
       |
       |5	      exponent	      in	 infiltration	      equation
       |
       |6	     infiltration	control      zone      depth	  (mm)
       |
       |7	  antecedent	soil	 moisture     (percent	   saturation)
       |
       |8				   USLE 			   'K'
       |
       +------------------------------------------------------------------------+



       After the soil parameters are input, a screen will prompt for groundwa-
       ter release fraction and tile drainage coefficient, which will apply to
       the  entire  watershed.	 The  tile  drainage coefficient indicates the
       design coefficient (mm/day) of tile drains in those areas designated as
       having  tile  drainage.	The groundwater release fraction is measure of
       the contribution of lateral groundwater movement or interflow to  total
       runoff.


       After  this  step  is  completed, it will provide an option to save the
       entered parameters to a file or printer for reference.	ANSWERS  soils
       inputs  will  then  be extracted and stored.  This step may be rerun to
       change any of the information.  Previously entered information will  be
       recalled and may be modified.



       SStteepp 33 CCaattaalloogguuee llaanndd uussee aanndd ssuurrffaaccee ppaarraammeetteerrss


       _M_a_p _i_n_p_u_t_: Land cover/use.
       _O_t_h_e_r _i_n_p_u_t_: Land cover parameters
       _D_e_s_c_r_i_p_t_i_o_n_:  For each category in the land use map found in the water-
       shed, ANSWERS requires values for  the  parameters  listed  below.  The
       Project	Manager facilitates preparation parameters by input into a ta-
       ble.



       +-------------------------------------------------------------------------+
       |Land  Cover  Parameters  for  ANSWERS  (see  ANSWERS  Users Manual for
       details) |
       +-------------------------------------------------------------------------+
       |1	short  (8  characters)	description of land use and management
       |
       |       (program will attempt to use map category description, if  any)
       |
       |2	 mm   of   potential   rainfall  interception  by  land  cover
       |
       |3	percentage  of	surface  covered   by	specified   land   use
       |
       |4	 oughness   coefficient   of  the  surface  (a	shape  factor)
       |
       |5	m  of  maximum	roughness  height  of  the   surface   profile
       |
       |6	Manning's  n  (a  measure  of  flow retardance of the surface)
       |
       |7      relative erosiveness (function of time and USLE	'C'  and  'P')
       |
       +-------------------------------------------------------------------------+



       After this step is completed, it will provide an  option  to  save  the
       entered	parameters  to a file or printer for reference.  ANSWERS cover
       inputs will then be extracted and stored.  This step may  be  rerun  to
       change  any of the information.	Previously entered information will be
       recalled and may be modified.



       SStteepp 44 IIddeennttiiffyy eelleevvaattiioonn--bbaasseedd iinnppuutt llaayyeerrss


       _M_a_p _i_n_p_u_t_: Slope and aspect.
       _D_e_s_c_r_i_p_t_i_o_n_: This step prompts for the  names  of  previously  prepared
       maps  of slope and aspect for the project watershed. It is important to
       note that the required format of slope and aspect maps vary  from  that
       created	by the rr..ssllooppee..aassppeecctt program. Programs have been developed to
       process an elevation surface map and create ANSWERS  slope  and	aspect
       map.  The elevation map should be true elevations in meters. The eleva-
       tion map can be "filtered" to remove "pits" and other  potential  prob-
       lems  to ANSWERS with the rr..ffiillll..ddiirr program.  The rr..ddiirreecctt program can
       be used to prepare an ANSWERS aspect map from the elevation layer  cre-
       ated  by rr..ffiillll..ddiirr.  The rr..ssllooppee..aassppeecctt program can be used to prepare
       an ANSWERS slope map from the elevation layer  created  by  rr..ffiillll..ddiirr.
       ANSWERS	requires slope values which are percent multiplied by 10 (so a
       slope map value of 35 indicated a slope of 3.5%).  The aspect map is  a
       critical  input	to  ANSWERS,  since  it  defines the routing of runoff
       through the watershed, and should  be  carefully  examined,  since  the
       rr..ddiirreecctt  program  is unable to create flawless output. The dd..rraasstt..eeddiitt
       programs have been developed to assist this manual inspection and edit-
       ing  process.   When editing the flow direction map, pay careful atten-
       tion to 1) cells on the watershed border, which all must flow into  the
       watershed.  2)  cells  that  will  be  declared as "channels" must flow
       directly from one to another (therefore it is suggested	that  channels
       should  be  identified in conjunction with this step). 3) flow from two
       cells must not point directly to each other (-><-)  or  otherwise  form
       circuitous  routes.  In the final flow map, one should be able to start
       at any cell in the watershed and follow the flow directions  from  cell
       to cell until arriving at the outlet cell.



       SStteepp 55 PPrreeppaarree rraaiinn ggaauuggee ddaattaa


       _M_a_p _i_n_p_u_t_: Rain gauge areas (for multiple gauges)
       _O_t_h_e_r _i_n_p_u_t_: Rain gauge data
       _D_e_s_c_r_i_p_t_i_o_n_:  This  step  is designed to organize data used to describe
       the precipitation event to be simulated. ANSWERS  permits  up  to  four
       rain  gauges to be used, each of which will require a table of rainfall
       data (time in minutes and rainfall intensity in millimeters per	hour).
       Data  from at least one rain gauge are required. If more than one gauge
       is used, you will need to prepare a raster map of the watershed area to
       indicate which cells are to represented by a given gauge's data.


       To  facilitate the modeling of a number of storms this step will prompt
       for a rainfall event name. The data tables entered will	be  stored  in
       the ANSWERS database under the event name.


       Rain gauge data for ANSWERS consists two columns of numbers.  The first
       is Time (in minutes) and the second is Rainfall Intensity (in mm/hour).
       Decimal	values	will be rounded to the closest whole number.  To input
       rain gauge data to the Project Manager, a file must first  be  prepared
       with  rain  gauge  data.   If multiple gauges are to be used, one input
       file is still used, data for each gauge are separated by  should  occur
       sequentially  by  gauge; so that data for gauge 1 is first in the file,
       data for gauge two is the second group of data, and so on.


       Example rain gauge data input files:



	       +----------+------------------------------------------+
	       |one gauge |    two gauges			     |
	       +----------+------------------------------------------+
	       |  0    0  |  0		0			     |
	       | 10    3  | 11		1	   data for gauge 1  |
	       | 20   10  | 25		7			     |
	       | 35   22  | -1 <----- delimiter 		     |
	       | 55    9  |  0		0			     |
	       | 67    4  | 15		6	   data for gauge 2  |
	       |100    0  | 10		4			     |
	       +----------+------------------------------------------+



       This step will prompt to determine if multiple rain gauges  are	to  be
       used. If so, it will prompt for the name of a map that represents areas
       to be assigned to the given gauges. The number of categories and  their
       value should match the number of rain gauges.  Next the program prompts
       for the name of the rain gauge data file.  The program reads  the  file
       and  displays what it found to the screen for approval. Having this, it
       will create the appropriate ANSWERS input files.



       SStteepp 66 IIddeennttiiffyy oouuttlleett cceellll


       _M_a_p _i_n_p_u_t_: none
       _O_t_h_e_r _i_n_p_u_t_: row and column number of watershed outlet element
       _D_e_s_c_r_i_p_t_i_o_n_: ANSWERS needs to know the row and  column  number  of  the
       element at the watershed outlet. To facilitate your finding this infor-
       mation, The raster map .ELEMENT has been created.  The category	values
       of  this  map are the sequentially numbered cells of the watershed. The
       category descriptions are the cell's row and  column  number.  Using  a
       tool  such as dd..wwhhaatt..rraasstt, the row and column number of the outlet cell
       can be queried from the displayed element map.



       SStteepp 77 SSppeecciiffyy aarreeaass wwiitthh ssuubbssuurrffaaccee ddrraaiinnaaggee


       _M_a_p _i_n_p_u_t_: _A_r_e_a_s _w_i_t_h _s_u_b_s_u_r_f_a_c_e _d_r_a_i_n_a_g_e _(_o_p_t_i_o_n_a_l_)
       _D_e_s_c_r_i_p_t_i_o_n_: This step offers a menu which allows the delineation of 1)
       all  the  watershed  with subsurface drainage, 2) none of the watershed
       with subsurface drainage, or 3) areas with subsurface  drainage	speci-
       fied  with  a  raster  map (all elements with a value greater than zero
       will be input to ANSWERS as  having  subsurface	drainage.   Note:  the
       drainage  coefficient  for  areas with subsurface is set with the other
       soils parameters in step 2. If "all" or "none" of the watershed is sim-
       ulated  as having subsurface drainage, no input map is required; other-
       wise a raster map is used to specify areas with subsurface drainage.



       SStteepp 88 CCaattaalloogguuee cchhaannnneell ppaarraammeetteerrss


       _M_a_p _i_n_p_u_t_: Channels
       _O_t_h_e_r _i_n_p_u_t_: Channel width and roughness coefficient for each  category
       of channel
       _D_e_s_c_r_i_p_t_i_o_n_:  Watershed	cells  with  a	well-defined channel should be
       defined to ANSWERS. ANSWERS  assumes  the  channel  is  rectangular  in
       cross-section and is sufficiently deep to handle runoff.


       To  prepare channel data for use with ANSWERS, the following is needed:
       a raster map layer of the channels in the watershed and	a  description
       of  width (meters) and roughness (Manning's "n") for each channel cate-
       gory found in the layer.


       It is suggested that the aspect map from Step 4 be created in  conjunc-
       tion  with the channel map, since ANSWERS will abort operation if a one
       channel element does not flow directly into  another  adjacent  channel
       element.



       SStteepp 99 DDeeffiinnee cchhaannnneell ssllooppeess


       _M_a_p _i_n_p_u_t_: Channel slope
       _D_e_s_c_r_i_p_t_i_o_n_: An optional input to ANSWERS is the slope of channels.  If
       a channel slope input is not given, ANSWERS assumes the slope  for  the
       channel is the same as the overland slope for the element.


       If  desired,  a	raster map may be used to define channel slope values.
       To do so, a raster map should be  prepared  with  category  values  for
       channel	slopes	in  tenths  of	a percent (i.e. a category value of 31
       would indicate a channel slope of 3.1 percent).


       Note: Even though channel slopes are an optional input to ANSWERS, this
       step must be run if only to say no map will be used.



       SStteepp 1100 SSppeecciiffyy BBMMPP''ss iinn wwaatteerrsshheedd


       _M_a_p  _i_n_p_u_t_:  Tile Outlet Terrace, Sedimentation Pond, Grassed Waterway,
       and/or Field Borders.
       _O_t_h_e_r _i_n_p_u_t_: Grassed waterway or field border width (meters)
       _D_e_s_c_r_i_p_t_i_o_n_: This step provides a menu to prepare any or  none  of  the
       four  structural  Best  Management Practices (BMPs) that ANSWERS recog-
       nizes.  Many BMPs can be described to  ANSWERS  by  changing  variables
       describing  the	surface  condition  of	the  soil. Practices which are
       tillage-oriented, for example, are described in the soils and land  use
       sections.  Gully structures such as a drop spillway may be simulated by
       reducing channel slope. On the other hand, BMPs which are structural in
       nature  require	a change in land use (row crop to grass for waterways,
       for example).  ANSWERS recognizes four optional	BMP  structures.  Even
       though  the  use of BMP structures is optional, this step still must be
       run to verify this.  NOTE: Since ANSWERS will recognize one BMP	for  a
       given  watershed  element,  the most effective BMP should be used.  The
       following is a brief discussion of the BMPs:


       1. ANSWERS Tile Outlet Terrace Assumptions:


       - Trap efficiency of 90%
       - Only lowermost terraces are described


       Also, if a terrace exists only in a portion of an element, the  assump-
       tion  is  made  that  all incoming flow is influenced by the BMP. Thus,
       elements which have only a small portion of the practice  within  their
       boundaries should not be given credit for the practice.


       2. ANSWERS Sedimentation Pond Assumptions:


       - Trap efficeincy of 95%
       -  Only	ponds  in upland areas should be defined. In stream structures
       are treated differently.


       Also, if a pond exists only in a portion of an element, the  assumption
       is made that all incoming flow is influenced by the BMP. Thus, elements
       which have only a small portion of the practice within their boundaries
       should not be given credit for the practice.


       3. ANSWERS Grassed Waterway Assumptions:


       -  The vegetated area with in the affected element is no longer subject
       to any sediment detachment.
       - The model deliberately prohibits deposition within the vegetation  of
       a  grass  waterway,  since any waterway that effectively traps sediment
       would soon fill and become ineffective.


       For each category found in the layer, you will be prompted for width of
       the waterway


       4. ANSWERS Field Border Assumptions


       -  The vegetated area with in the affected element is no longer subject
       to any sediment detachment.


       For each category found in the layer, you will be prompted for width of
       the field border.



       SStteepp 1111 PPrreeppaarree AANNSSWWEERRSS iinnppuutt aanndd rruunn ssiimmuullaattiioonn


       _D_e_s_c_r_i_p_t_i_o_n_:  Steps  1-10 must have a status of "done" before this step
       can be run. (Even steps for optional  inputs  must  be  run  before  an
       ANSWERS input file can be completed.) Each of the prior steps will have
       prepared their part of the ANSWERS input. The first  function  of  this
       step is to compile all the parts together.  Once the input file is com-
       plete, the simulation can be  run.   (NOTE:  r.answers  will  call  the
       ANSWERS	program,  which  must  be  compiled as a part of the r.answers
       installation. The source code for ANSWERS should be part of  the  soft-
       ware  distributed with r.answers.)  The error messages that ANSWERS may
       send to "standard output" are captured to a file by r.answers and  dis-
       played.	 If  none,  a  message	to  that effect will be printed to the
       screen (although this doesn't mean that	the  simulation  ran  entirely
       error-free).  The  primary  output  of  the  simulation	is captured to
       another file, then processed to separate it into component parts of



       1) _t_e_x_t - the verbose reiteration
	      of the inputs and summary of watershed characteristics. This  is
	      useful  for  checking  to  insure  that  inputs  were read in by
	      ANSWERS properly; 2) _o_u_t_l_e_t _h_y_d_r_o_g_r_a_p_h _d_a_t_a of rainfall,	runoff
	      and  sediment  yield  and  concentration.  If  these data are in
	      order, they will be processed into  a  format  readable  by  the
	      dd..lliinneeggrraapphh program for display; 3) _i_n_d_i_v_i_d_u_a_l _e_l_e_m_e_n_t _n_e_t _s_e_d_i_-
	      _m_e_n_t_a_t_i_o_n showing sediment loss or deposition, if any, for  each
	      raster element in the watershed.


       Also,  _s_e_d_i_m_e_n_t	_d_e_p_o_s_i_t_i_o_n _i_n _c_h_a_n_n_e_l _e_l_e_m_e_n_t_s.  This step will prompt
       for names to use for new watershed maps it will	create	by  extracting
       these data from the output. If the simulation event did not create sed-
       iment loss or deposition, or channel deposition for the	scenario,  the
       given  map  will  not be created.  To find out how to access the output
       files, see the description of step 12, below.



       SStteepp 1122 MMiisscceellllaanneeoouuss CCoommmmaanndd MMeennuu


       This step calls a menu that



       1) allows access to the project files in the
	      project database and to 2) a function that prepares a summary of
	      the project's current status.


       The  project database is where rr..aannsswweerrss stores all the inputs, output,
       and other non-map data associated with the  project.  See  the  "FILES"
       section	(below)  for  more  information. There are two sections to the
       project data, since rainfall data are kept  in  a  separate  directory.
       When  using  this  step to access database files, the program will list
       both the project data and the rain data files, and  ask	which  section
       you  wish to access. Next you will be prompted for the name of the file
       to access. This request will be turned over to the "file  handler  pro-
       gram"  which  facilitates  sending  a  file  to	the screen, copying to
       another file, or printing.


       The project status function available under step 12 creates  a  helpful
       summary	of  the  project, and then passes control to the "file handler
       program" for display, copying to a file, or printing.



FFIILLEESS
       Index of ANSWERS on GRASS database files


       Each project  will  create  and	use  the  following  files  in	$LOCA-
       TION/answers//data.  For the most part, there isn't much to see, unless
       something is not working right. If that is the case, The first thing to
       check  would  be  files	listed	here under the Output section or Input
       file. Furthermore, attempting to fix a problem by editing any of  these
       files  could  prove  to	have  unpredictable results. Once a problem is
       identified (with the input maps or parameters,  most  likely)  fix  the
       input  maps if need be, run r.answers again to make any changes, such a
       using a different map or correcting parameters. Remember that if a  map
       is changed the menu step that uses it must be run again to resample the
       inputs. Run step 11 again  to  create  a  new  input  file  and	re-run
       ANSWERS.




       General project data

       reclass	      reclass rules to create project MASK
       region	       project region coordinates

       AANNSSWWEERRSS IInnppuutt ffiillee


       answers_input   file created to use as input to ANSWERS


       AANNSSWWEERRSS OOuuttppuutt


       When  ANSWERS  is run, output from stdout is sent to answers_output and
       anything that may go to stderr is captured in answers_error. After that
       the  output  is cut into sections. (if something unpredictable happened
       when ANSWERS ran, then the output and the files extracted from  it  may
       be  garbled;  reading  answers_output  and  answers_error  may  provide
       clues).

       answers_output  complete output from running answers
       answers_error   errors captured when answers is run
       out_chnl        channel deposition data
       out_sediment    element sediment deposition/loss data
       out_text        verbose input reiteration
       out_hydro       outlet hydrograph data

       The outlet hydrograph data is broken into 5 files to use  as  input  to
       dd..lliinneeggrraapphh

       hydro_time      time increments of simulation (minutes)
       hydro_rain      rainfall (mm/h)
       hydro_runoff    runoff at outlet (mm/h)
       hydro_sed1      cumulative sediment at outlet (kg)
       hydro_sed2      sediment concentration in runoff (mg/l)

       AANNSSWWEERRSS EElleemmeenntt ddaattaa


       Element	data  files  are extracted from input maps.  Each line is data
       for a watershed cell element.  When answers  input  is  created,  these
       files are used to create the element data section.

       in_row_col      watershed row and column number
       in_soil	       soil type
       in_cover        land use
       in_elev	       slope and aspect
       in_chnl	       channel element data
       in_rain	       rain gauge number
       in_tile	       subsurface drainage flag

       AANNSSWWEERRSS PPrreeddaattaa


       The  following  files  are  used  to  form the "predata" section of the
       answers input file.

       chnl_predata    description of channel types
       cover_predata   description of cover parameters
       soil_predata    description of soil parameters
       rain_predata    rain gauge data

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       These files are used by the project manager  to	"remember"  parameters
       used to create the respective predata files, allowing the parameters to
       be read back by the program for editing.

       chnl_data       channel parameters
       cover_data      cover parameters
       soil_data       soil parameters


SSEEEE AALLSSOO
       Answers Manual

       Answers Exercises

       Demonstartion scripts in the answer source tree


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AAUUTTHHOORR
       Chris Rewerts, Agricultural Engineering, Purdue University

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GRASS 5.0							  r.answers(1)
