~ ~ ~ PURPOSE ~ ~ ~
Predicts daily runoff given breakpoint precipitation and snow melt
using the Green & Ampt technique
~ ~ ~ INCOMING VARIABLES ~ ~ ~
name |units |definition
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
wst(:)%weat%ts(:) |mm H2O |precipitation for the time step during day
swtrg(:) |none |rainfall event flag:
| 0: no rainfall event over midnight
| 1: rainfall event over midnight
wfsh(:) |mm |average capillary suction at wetting front
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ ~ ~ OUTGOING VARIABLES ~ ~ ~
name |units |definition
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
hhqday(:) |mm H2O |surface runoff generated each hour of day
|in HRU
surfq(:) |mm H2O |surface runoff for the day in HRU
swtrg(:) |none |rainfall event flag:
| 0: no rainfall event over midnight
| 1: rainfall event over midnight
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~
Intrinsic: Sum, Exp, Real, Mod
~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~
reset values for day calculate effective hydraulic conductivity calculate total amount of rainfall during day for time step and rainfall intensity for time step urban 60./idt NK Feb 4,08
if rainfall intensity is less than infiltration rate everything will infiltrate if rainfall intensity is greater than infiltration rate find cumulative infiltration for time step by successive substitution urban 60./idt NK Feb 4,08 Urban Impervious cover effective pcp is > 0.017 mm/min (or 4/100 inches/hr) the potential for initial dabstraction from paved surface is less than the user input initial dabstraction the potential for initial dabstraction from paved surface increases based on evaporation daily total runoff calculate new rate of infiltration