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 Nonpoint 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  ero-
       sion and sediment control on complex watersheds, and water
       quality analysis associated with sediment associated chem-
       icals.


       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 further comple-
       tion or modification. The first menu one  encounters  when
       running	rr..aannsswweerrss includes functions to create a new pro-
       ject, 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 functions.

	  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 number. If a step has not been run, no status is
       displayed (as seen above). If the step has  been  success-
       fully  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	following
       keystroke  guide is helpful to know when using the parame-
       ter 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 cancel 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 practical, 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, Indiana, 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 por-
       tions 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  automatically  set.
       Project	resolution  is input in meters and it used to set
       the size of the watershed elements to be used in the simu-
       lation. 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 calculated 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 automatically 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 refer-
       ing to raster cells. Raster values of the map  will  indi-
       cate  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 infil-
       tration	       |
       |			  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 groundwater release fraction and tile drainage coeffi-
       cient, 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 hav-
       ing tile drainage.  The groundwater  release  fraction  is
       measure	of  the contribution of lateral groundwater move-
       ment 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 ref-
       erence.	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 watershed, ANSWERS requires values for the  parame-
       ters  listed below. The Project Manager facilitates prepa-
       ration parameters by input into a table.



       +-------------------------------------------------------------------------+
       |Land Cover Parameters for ANSWERS (see ANSWERS Users Man-
       ual for details) |
       +-------------------------------------------------------------------------+
       |1	short  (8 characters) description of land use and
       management	|
       |       (program will attempt to use map category descrip-
       tion, 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 fac-
       tor)		 |
       |5      m of maximum roughness height of the surface  pro-
       file		 |
       |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 ref-
       erence.	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  water-
       shed.  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 eleva-
       tions in meters. The elevation map can  be  "filtered"  to
       remove "pits" and other potential problems 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
       created 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  val-
       ues  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 devel-
       oped to assist this manual inspection and editing process.
       When editing the flow direction map, pay careful attention
       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 (there-
       fore 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 min-
       utes 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 num-
       bers.  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 num-
       ber  of the element at the watershed outlet. To facilitate
       your finding this information, 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 specified
       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  simulated  as
       having subsurface drainage, no input map is required; oth-
       erwise a raster map is used to specify areas with  subsur-
       face 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 follow-
       ing is needed: a raster map layer of the channels  in  the
       watershed  and  a description of width (meters) and rough-
       ness (Manning's "n") for each channel  category	found  in
       the layer.


       It is suggested that the aspect map from Step 4 be created
       in conjunction 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 over-
       land 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	recognizes.   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 water-
       ways,  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  assumption	is  made that all incoming flow is influ-
       enced 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  influ-
       enced  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 complete, 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 software
       distributed with  r.answers.)   The  error  messages  that
       ANSWERS	may  send  to "standard output" are captured to a
       file by r.answers and displayed.  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 characteris-
	      tics. 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  read-
	      able  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  sedi-
	      ment  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 sediment loss or depo-
       sition, 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 informa-
       tion. 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  program"  which
       facilitates  sending  a	file  to  the  screen, copying to
       another file, or printing.


       The project status function available under step  12  cre-
       ates  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
       $LOCATION/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. Fur-
       thermore, 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 cap-
       tured 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 ele-
       ment 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

	PPaarraammeetteerr ddaattaa


       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


       _d_._I_N_T_R_O

       _d_._r_a_s_t_._e_d_i_t

       _d_._r_a_s_t_._n_u_m

       _d_._w_h_a_t_._r_a_s_t

       _r_._s_l_o_p_e

       _r_._f_i_l_l_._d_i_r

       _r_._d_i_r_e_c_t

       _p_a_r_s_e_r

AAUUTTHHOORR
       Chris Rewerts, Agricultural Engineering, Purdue University

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_4 _$



GRASS 5.0					     r.answers(1)
