Tile Flow

When drainage tiles are installed in a pothole, the pothole will contribute water to the main channel through tile flow. The pothole outflow originating from tile drainage is:

$V_{flowout}=q_{tile}*86400$ if $V>q_{tile}*86400$ 8:1.3.12

$V_{flowout}=V$ if $V \le q_{tile}*86400$ 8:1.3.13

where $V_{flowout}$ is the volume of water flowing out of the water body during the day (m$^3$ H$_2$O), $q_{tile}$ is the average daily tile flow rate (m$^3$/s), and $V$ is the volume of water stored in the pothole (m$^3$ H$_2$O).

Table 8:1-3: SWAT+ input variables that pertain to potholes.

Variable Name	Definition	File Name
IPOT	Number of HRU that is impounding water (that contains the pothole)	.hru
MONTH/DAY or HUSC	Timing of release/impound operation.	.mgt
MGT_OP	Operation code. MGT_OP = 13 for release/impound operation	.mgt
IMP_TRIG	Release/impound action code: 0: impound, 1: release	.mgt
SLOPE	$slp$: Slope of the HRU (m/m)	.hru
POT_FR	$fr_{pot}$: Fraction of the HRU area draining into the pothole	.hru
EVLAI	$LAI_{evap}$: Leaf area index at which no evaporation occurs from the water surface	.bsn
POT_VOLX	$V_{pot,mx}$: Maximum amount of water that can be stored in the pothole (mm)	.hru
POT_TILE	$q_{tile}$: Average daily tile flow rate (mm)	.hru