r.agnps50.input(1)     Grass User's Manual     r.agnps50.input(1)



GGuuiiddeelliinneess ffoorr AAGGNNPPSS--GGRRAASSSS IInnppuutt IInntteerrffaaccee
       The  major objective of the AGNPS-GRASS input interface is
       to minimize the user interaction in  preparing  the  input
       data  for  the  AGNPS  model and to minimize the number of
       user supplied/developed GIS database  layers.  Of  the  22
       different  data	required  by  the  model  for  each  cell
       (appendix 2), the interface will prepare  the  input  data
       with  only  8  (appendix 2) basic GIS database layers sup-
       plied by the user and with minimal user interaction. There
       are  5 (appendix 2) parameters needed for the whole water-
       shed which will be obtained from the user.


       NNaammee  ooff  tthhee   AAGGNNPPSS--GGRRAASSSS   IInnppuutt   IInntteerrffaaccee	 PPrrooggrraamm:
       _r_._a_g_n_p_s_5_0_._i_n_p_u_t


       PPrroocceedduurreess ttoo ffoollllooww wwhhiillee eexxeeccuuttiinngg tthhee IInnppuutt IInntteerrffaaccee:


       First  start GRASS 5.x from a shelltool window with proper
       mapset where the data resides


       Execute _r_._a_g_n_p_s_5_0_._i_n_p_u_t program from the shelltool  window
       where GRASS is running


       A _W_a_t_e_r_s_h_e_d _I_n_p_u_t menu will appear on the shelltool window
       requesting the following data/information from the user:


       Watershed  Description:	Enter  a  description  about  the
       watershed.  This  information  optional and will appear in
       both input and output of the AGNPS model run.


       Rainfall Amount in inches: Enter the total amount of rain-
       fall in inches.


       Erosivity Index Value: Enter the erosivity index value for
       that particular storm/rainfall event.


       Enter the cell size in meters: The length of the side of a
       cell  in  meters  is  entered. The square of the cell size
       will be the area of each cell.


       Enter a file name to save in AGNPS format:  Enter  a  file
       name with created by the AGNPS-GRASS input interface tool.
       This will be stored in the current working directory.


       Enter the watershed name: The name of the watershed should
       be  entered  here.   All  the input layers should have the
       same watershed name with the proper  extension  (as  _X  in
       appendix  1).  Please  refer  to  appendix 1 for the valid
       extensions  and	valid  category  labels/values	that  are
       allowed for each layer.


       Then hit the _E_s_c key to continue.




       Error  Messages:  If any of the category labels/values for
       the input layers is not valid, an error message is printed
       and  the program quits. Run _s_u_p_p_o_r_t on the layer where the
       category label is wrong to correct it. The program _s_u_p_p_o_r_t
       helps  to  modify  the  supporting  files  of a map, which
       include	header,  category,  color,   and   history.   The
       wrong/misspelled  category labels can be corrected by run-
       ning _s_u_p_p_o_r_t on the layer to be corrected and choosing the
       category  option.  If  there  is any problem with the flow
       direction layer, error messages are printed for those cell
       numbers that had problems and the nature of those problems
       (like circularity, sinks  or  holes,  or  flow  directions
       pointing  at  each other).  Use _D_e_d_i_t on the aspect map to
       correct the problems. The _D_e_d_i_t program helps  to  display
       and  edit  the  aspect map with arrows on it, which should
       enable one to correct the flow direction on a cell by cell
       basis.


       For   each  run	of  this  input  interface  tool,  a  new
       _t_e_m_p___c_e_l_l___n_u_m layer is created and stored in  the  current
       mapset.	In  this  map, the cells are numbered from top to
       bottom and left to right. This is a useful layer for edit-
       ing and interpreting the error messages due to conflicting
       flow direction for any particular cell.	While  using  the
       _D_e_d_i_t  program  to correct the errors, this map allows one
       to locate the cell number where conflicts occur.


       Once the input interface completes its run without errors,
       it saves the data in the AGNPS format. The AGNPS model can
       be executed with this data. The	name  of  the  executable
       file  program to run the AGNPS model is _a_g_r_u_n.  Type _a_g_r_u_n
       from the shelltool window where GRASS is running. The pro-
       gram  will  ask for the input file name. Enter the name of
       the file that was saved by running the  AGNPS-GRASS  input
       interface, with the _._d_a_t extension.  The model will output
       the results of the run with a _._n_p_s extension.  Both  input
       and  output  ASCII  files are needed to execute the AGNPS-
       GRASS output interface tool (the Visualization tool).


       AAppppeennddiixx 11



       Watershed boundary

	      (XX.wshd) Should have category values greater than 0
	      within  the watershed and 0's outside of the water-
	      shed boundary.

       Elevation

	      (XX.elev) Elevation data in  meters  should  be  the
	      category	values	for  each cell. Also make sure at
	      least 1 row and column of data around the watershed
	      boundary exists to estimate slope and aspect at the
	      boundary of the watershed.

       Aspect

	      (XX.asp.cell_size) The aspect map should have values
	      between _1_-_8 as category values  and should not have
	      any sinks, circularity or  more  than  one  outlet.
	      Cell_size  is  the number that the user entered for
	      question 4 in the interface input menu.  For  exam-
	      ple,  if	the  watershed is modeled for a 100 meter
	      cell size, then  the  aspect  map  name  should  be
	      XX.asp.100

       Soils

	      (XX.soils)  If  any of the soil attribute (K factor,
	      clay, sand or hydrological soil group) maps do  not
	      exist,  then  the  program looks for XX.soils map to
	      extract information from	the  Soils-5  data  base.
	      (currently this is not working fully).

       USLE K factor

	      (XX.K)  The  USLE	K  factor  map should contain the
	      value of the K factor as	the  category  label  for
	      each cell. This is obtained from the soil type map.

       Hydrological soil group

	      (XX.hyg) The category labels allowed are  either  _A,
	      _B, _C, or _D and should appear as category labels for
	      each cell. This is obtained from the soil type map.

       Sand
	      (XX.sand)	The  percentage of sand content should be
	      the category label for each cell.  This is obtained
	      from the soil type map.

       Clay
	      (XX.clay)	The  percentage of clay content should be
	      there as a category label for each  cell.  This  is
	      obtained from the soil type map.

       Land use

	      (XX.luse)	The  land use map category labels allowed
	      are _f_a_l_l_o_w, _r_o_w _c_r_o_p_s, _s_m_a_l_l _g_r_a_i_n, _l_e_g_u_m_e_s,  _r_o_t_a_-
	      _t_i_o_n  _m_e_a_d_o_w, _c_l_o_s_e_-_s_e_e_d_e_d _l_e_g_u_m_e_s, _p_a_s_t_u_r_e, _r_a_n_g_e,
	      _m_e_a_d_o_w, _w_o_o_d_s, _w_o_o_d_l_a_n_d, _g_r_a_s_s _w_a_t_e_r_w_a_y, _h_a_r_d  _s_u_r_-
	      _f_a_c_e, _f_a_r_m_s_t_e_a_d_s, _r_o_a_d_s _(_d_i_r_t_), _w_a_t_e_r, or _m_a_r_s_h.

       Management Practice

	      (XX.mgpr)	 The  management  practice  map  category
	      labels allowed are _s_t_r_a_i_g_h_t _r_o_w, _c_o_n_t_o_u_r_e_d, or _c_o_n_-
	      _t_o_u_r_e_d _a_n_d _t_e_r_r_a_c_e_d.

       Nutrient

	      (XX.nut)  The  cell  value  should correspond to the
	      level of fertilizer application, i.e _1, _2, _3 or  _0.
	      Where 1-low, 2-medium, 3-high and 0-urban, water or
	      marsh.  (refer fertilizer level table).

       Machinery

	      (XX.mach) This map is used to  find  the  fertilizer
	      availability factor for the top 1 cm depth of soil.
	      The category labels allowed are _l_a_r_g_e _o_f_f_s_e_t  _d_i_s_k,
	      _m_o_l_d_b_o_a_r_d  _p_l_o_w,	_l_i_s_t_e_r,  _c_h_i_s_e_l _p_l_o_w, _d_i_s_k, _f_i_e_l_d
	      _c_u_l_t_i_v_a_t_o_r, _r_o_w _c_u_l_t_i_v_a_t_o_r,  _a_n_h_y_d_r_o_u_s  _a_p_p_l_i_c_a_t_o_r,
	      _r_o_d  _w_e_e_d_e_r, _p_l_a_n_t_e_r, _s_m_o_o_t_h, or _n_o _t_i_l_l. The cate-
	      gory label for urban, water,  marsh  or  farmsteads
	      can  be  no till or smooth (refer fertilizer avail-
	      ability factor table).

       Channel slope

	      (XX.chsl) A channel slope length map has to be  pre-
	      pared  by  the  user.   Percentage of channel slope
	      should be the value of the category in  that  cell.
	      If  this	layer is missing, the user has the choice
	      to either enter the name of  layer  which  has  the
	      channel  slope  values  or  can  accept the default
	      value of 50% of the overland  slope  value  as  the
	      channel  slope value (recommended by the AGNPS man-
	      ual).

       Slope length factor

	      (XX.slen) A slope length factor layer in feet has to
	      be  prepared  by	the user for each cell. The value
	      should be the value of the category in that cell.

       USLE C factor

	      (XX.C) The USLE C	factor	map  should  contain  the
	      value  of  the  C  factor as the category label for
	      each cell.


FFeerrttiilliizzaattiioonn lleevveell
       ----------------------------------------------------------
       |Level of      | Assumed fertilization (lb/acre) |	|
       |fertilization | 	 N	   P		| Input |
       |--------------------------------------------------------|
       |None			 0	   0		|  0	|
       |Low			50	   20		|  1	|
       |Medium		       100	   40		|  2	|
       |High		       200	   80		|  3	|
       ----------------------------------------------------------


FFeerrttiilliizzeerr aavvaaiillaabbiilliittyy ffaaccttoorrss aaccccoorrddiinngg
       to tillage practice

       --------------------------------------------------------------
       Tillage practice 	 Fertilizer  availability  factor
       (%)
       --------------------------------------------------------------
       Large offset disk		      40
       Moldboard plow			      10
       Lister				      20
       Chisel plow			      67
       Disk				      50
       Field cultivator 		      70
       Row cultivator			      50
       Anhydrous applicator		      85
       Rod weeder			      95
       Planter				      85
       Smooth or no till		     100
       --------------------------------------------------------------

       AAppppeennddiixx 22:: AAGGNNPPSS cceellll iinnppuutt ppaarraammeetteerrss

       box;
       l.
       1. Cell number
       2. Number of cell into which it drains
       3. SCS curve number
       4. Average slope %
       5. Slope shape factor
       6. Average field slope length
       7. Average channel slope
       8. Slope length factor
       9. Mannings roughness coefficient for channel
       10. Soil erodibility factor (K) from USLE
       11. Cropping factor (C) from USLE
       12. Practice factor (P) from USLE
       13. Surface condition constant (based on land use)
       14.  Aspect  (one of 8 directions indicating drainage from
       cell)
       15. Soil texture (sand, silt, clay, peat)
       16. Fertilization level (zero, low, medium, high)
       17. Incorporation factor (% fertilizer left in top 1 cm of
       soil)
       18. Point source indicator (indicates existence of a point
       source input within a cell)
       19. Gully source level (estimate of amount, tons, or gully
       erosion in a cell)
       20. Chemical oxygen demand factor
       21. Impoundment factor (indicating presence of an impound-
       ment terrace system within the cell)
       22. Channel indicator (indicating existence of  a  defined
       channel within a cell)


       The  8  basic input GIS layers required for extracting the
       data by the AGNPS-GRASS input interface tool are:

	      Soils

	      Elevation

	      Land use

	      Management practice

	      Fertilizer or nutrient inputs

	      Type of machinery used for land preparation

	      Channel slope

	      Slope length factor

       Five pieces of data are required for the total watershed:

	       Watershed identification/description

	       Precipitation (inches)

	       Erosion Index (EI-value) for  that  storm/rainfall
	      event

	       Area of each cell (acres)

	       Outlet cell number

       An  important  implication  of this set is that AGNPS does
       not accommodate non-uniform storms, _i_._e_. it uses a  lumped
       modeling approach for its rainfall.


       For  each  watershed element, AGNPS requires the following
       22 input data values (its distributed  parameter  informa-
       tion):

	       Cell number

	       Number of the cell into which it drains

	       SCS curve number

	       Average land slope (%)

	       Slope shape factor (uniform, convex or concave)

	       Average field slope length (feet)

	       Average channel slope (%)

	       Average channel side slope (%)

	       Mannings roughness coefficient for the channel

	       Soil erodibility factor (K) for USLE

	       Cropping factor (C) for USLE

	       Practice factor (P) for USLE

	       Surface	condition  constant (factor based on land
	      use)

	       Aspect (one of 8  possible  directions  indicating
	      the principal drainage direction from the cell)

	       Soil texture (sand, silt, clay, peat)

	       Fertilization level (zero, low, medium, high)

	       Incorporation  factor  (% fertilizer left in top 1
	      cm of soil)

	       Point source indicator (indicates existence  of	a
	      point source input within a cell)

	       Gully  source  level (estimate of amount, tons, of
	      gulley erosion in a cell)

	       Chemical oxygen demand factor

	       Impoundment factor (indicating the presence of  an
	      impoundment terrace system within the cell)

	       Channel	 indicator  (indicating  existence  of	a
	      defined channel within a cell)


SSEEEE AALLSSOO
       _r_._a_g_n_p_s_5_0_._r_u_n

       _r_._a_g_n_p_s_5_0_._v_i_e_w



       AGNPS Page

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GRASS 5.0				       r.agnps50.input(1)
