Scientific Investigations Report 2006–5318
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006–5318
cropcof_dpm.f
Declares, initializes, and then sets values for the land use/cover parameters.
Declares, initializes, and then sets, for each day, the parameters for any of the 31 land uses/covers present in the modeled area. Module based on Bauer and Vaccaro (1987) with additional land uses/covers added.
July, 2004
fcmax
Maximum foliar cover of a land use/cover, in decimal percent.
maxint
Maximum interception capacity of a land use/cover, in inches.
rdmax
Maximum root depth of a land use/cover, in inches.
irrst1
Start date for first irrigation scheduling period, in monthday (June 9 is 0609)
irren1
End date for first irrigation scheduling period, in monthday (June 9 is 0609)
irrst2
Start date for second irrigation scheduling period, in monthday (June 9 is 0609)
irren2
End date for second irrigation scheduling period, in monthday (June 9 is 0609)
irrscd
Irrigation scheduling type: =0 constant, =1 growth stage, no units.
sumcp (calculated)
Crop curve integrated over the input irrigation season, no units.
iroot
Distribution of root mass in root zone: linear (=0) or exponential (=1), no units.
fallow (calculated)
Winter wheat (2-yr cycle) swapping of land-use type 5 to 6, no units.
cov_type
HRU cover type: land use/cover type, from 1-31, no units. [basin]
coefs
Daily values of 6 parameters for each of the crop-types, units vary.
none
In the initialization part of the module the two irrigation scheduling periods start and end dates are converted from a monthday (e.g., 0906 is June 9) to Julian day. This conversion uses the array jdym(12) that stores the Julian day for the first day of each month. If only one irrigation period, the start date of the second period should be set to the day after the end date of the first period, with the end date of the second period set to the actual end of irrigation.
The crop growth curves are next integrated over the irrigation season by a call to subroutine schedule in order to apportion irrigation according to the growth curve. This apportioning only occurs when the user defined parameter irrscd is set equal to one (irrscd=1), other wise the irrigation is applied evenly throughout the crop growth. The integrated sum is stored in the variable sumcp(nlands), where nlands goes from 0 to the maximum number of land uses (currently 31 and listed in Appendix 1 of documentation report). For wheat crops that are fallow every other year the initalization module implements a counter (fallow) that will be greater than 1 for the case of any HRU having a land use of 5 or 6. Last, the variable coefs is initialized to zero.
The run module first checks if the first growing season is over and fallow is greater than 0. If these cases are true, then the land use for dryland wheat crops with a 2-year growing cycle are swapped. The alfalfa crop coefficient (cpalf) for this day (jday) is next found by a call to subroutine alftoday. Alfalfa is the reference crop for the Jensen-Haise (J-H) PET method (Jensen, 1973; Jensen and others, 1990) and needs to be accounted for in the individual crop coefficients. Some coefficients from the Doorenboos and Pruitt (1977) and Allen and others (1998) are grass-based using the Penman-Montieth method but these values are similar to or slightly larger than the alfalfa J-H.
For each land use (1 to nlands) a subroutine is called, when appropriate, for this day (jday) to find the current root depth (rd), foliar cover (fc), interception capacity (mxnt), crop coefficient (cp), and multiplying factor for irrigation application (apmult). For the agricultural crops, cp is then divided by cpalf. These values are then stored in the variable coefs along with the maximum root depth (see above description).
The land use/cover subroutines with actual name of subroutine are (none for water or impervious land covers):
forest (conifer forests)
grass
sage
wwalyr (winter wheat harvested this summer and planted this fall--all year)
wwsprg (winter wheat harvested this summer fallow to next fall)
wwautm (winter wheat fallow this spring and planted this fall)
orchrd (includes decidous trees)
alfalf
row (row crops)
corn
potato
sand
pealen (peas and lentils)
sprgwt (spring wheat)
smalveg (small vegtables)
cotton
mint
grapecal (grapes in California)
grapewaor (grapes in Washington and Oregon)
hops (for good beer)
olive
citrus
soy
apple
sorghum
pasture
bean
pea
asparagus
For each of the above subroutines, the current rd, fc, and mxnt are based on the ratio of the current crop coefficient (cp) to the maximum crop coefficient multiplied by the maximum values for rd (rdmx), fc (fcmx), and mxnt (maxint). In turn, the maximum values are either user defined or set as defaults in each subroutine. If set as defaults, then no need to input the parameter. Last, the variable apmult is calculated as the ratio of cp to sumcp.
Allen, R.G, Pereira, L.S., Raes, Dirk, and Smith, Martin, 1998, Crop evapotranspiration-Guidelines for computing crop water requirements: Irrigation and Drainage Paper 56, Chapter 6-Single crop coefficient, Food and Agriculture Organization of the United Nations, Rome, Italy, 41 p.
Bauer, H.H., and Mastin, M.C., 1997, Recharge from precipitation in three small glacial-till mantled catchments in the Puget Sound Lowlands: U. S. Geological Survey Water-Resources Investigations Report 96-4219, 119 p.
Bauer, H.H., and Vaccaro, J.J., 1987, Documentation of a deep percolation model for estimating ground-water recharge: U. S. Geological Survey Open-File Report 86-536, 180 p.
Doorenboos, J., and Pruitt, W.O., 1977, Crop Water Requirements: Irrigation and Drainage Paper 24, Food and Agriculture Organization of the United Nations, Rome, Italy, 148 p.
Jensen, M.E., ed., 1973, Consumptive use of water and irrigation water requirements: New York, American Society of Civil Engineers, Irrigation and Drainage Division, 215 p.
Jensen, M.E., Burman, R.D., and Allen, R.G., eds., 1990, Evapotranspiration and irrigation water requirements: A.S.C.E. Manuals and Reports on Engineering Practice No. 70, 332 p.
John J. Vaccaro and Henry H. Bauer
U.S. Geological Survey
Washington Water Science Center
934 Broadway, Suite 300
Tacoma, WA 98402
Modified by:
John J. Vaccaro
U.S. Geological Survey
Washington Water Science Center
934 Broadway, Suite 300
Tacoma, WA 98402
Telephone: 253-552-1620
Fax: 253-552-1581
Email: jvaccaro@usgs.gov
U.S.
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