This is the appearance of the Land Uses tab of the System Coefficients dialog:
Following is a description of the parameters associated with Land Uses. Refer to the main System Coefficients page for information on other categories of coefficients. To save the changes made when closing this dialog, click OK. To ignore changes, click Cancel.
Under Land Uses, the land use types for a watershed are chosen and the parameters for those land uses are set. To add or remove land use types, click on Edit List. The following dialog box will appear:
Click on Add to add a new land use called (Unspecified) at the end of the list. Its default coefficients will be the same as those of the first land use type in the list. Click on any land use in the list and then click Remove to remove it from the list, or Move Up or Move Down to move the land use within the list. To change the name of a land use, enter the new name in the spreadsheet to replace the existing name. Note that if a land use is removed, all catchments which were more than 0 percent of that land use will no longer have land uses which add up to 100%.
There are many parameters in the list next to Parameter:. When each is selected, the spreadsheet changes to show the values of that parameter for each land use.
Open in Winter is the fraction of snow covered land exposed to sunlight (not shaded)
Cropping Factor is the erosivity multiplier based upon vegetation. (0.1 – 0.8, unitless)
Rainfall Detachment Factor is the proportionality parameter between the square of rainfall intensity and soil detachment. (normally 0.108 g / cm3 for exposed soil, otherwise 0)
Flow Detachment Factor is the proportionality parameter between overland flow and soil detachment. (normally 0.9 kg / m4)
Fraction Impervious is that portion of the land use which is impervious to infiltrating water (0 – 1, unitless)
Interception Storage is the depth of water which can be stored in the canopy. (0 – 0.3 cm)
Long-term Growth is the annual productivity multiplier. (1.0 – 1.2, unitless)
Leaf Growth Factor is the annual leaf production multiplier. (usually 1.0, unitless)
Productivity is the productivity of the land use. (0 – 1.2 kg / m2 / yr)
Active Respiration is the respiration rate for growth. (0 – 1E-7 / day)
Maintenance Respiration is the respiration rate for maintenance. (0 – 6E-8 / day)
Dry Collection Efficiency is the collection efficiency when the canopy is dry. (0.6, unitless)
Wet Collection Efficiency is the collection efficiency when the canopy is wet. (0.9, unitless)
Leaf Weight / Area is the ratio of leaf weight to leaf surface area. (0.005 – 0.01g / cm2)
Canopy Height is the height of the canopy. (0 – 50 m)
Stomatal Resistance is the stomatal resistance to gas uptake. (1 – 3 s / cm)
Leaf Area Index is the ratio of leaf area to ground surface area for each month of the year. (0 – 12, unitless)
Annual Uptake Distribution is the fraction of annual uptake which occurs in each month. The sum over all months should be 1. (0 – 0.3, unitless)
Litter Fall Rate is the amount of dead material dropped from vegetation in each month of the year. (0 – 0.2 kg / m2 / month)
Exudation Rate is the amount of solutes secreted onto the canopy surface in each month of the year. (0 – 2E-5 / day)
Leaf Composition is the proportion of each constituent in leaves relative to dry leaf mass. (0 – 20 mg constituent / g dry weight)
Trunk Composition is the proportion of each constituent in the trunk relative to dry trunk mass. (0 – 1 mg constituent / g dry weight)