K2 Precipitation output

[Amit Kallush]

Hi,

I'm not sure this is the right place, but I didn't find any K2 support forum.

Part of the K2 output is a precipitation column. Does anyone know what it represents? Is it the average rainfall upstream to the selected element? If so, what kind of average? 

I'm trying to figure out why my results' precipitation output looks wired.

Thanks!

Amit

[Shea]

There is a K2 Google Group (https://groups.google.com/g/kineros-support/), but because it has not been widely advertised or seen any activity I'm happy to answer here.

The Rainfall column in the tabular summary at the bottom of the .OUT file represents the rainfall volume that falls on each element. In the parameter file, if the interception depth for an element is equal to 0, then the volume of the rainfall on that particular element will equal the depth of rainfall multiplied by the element area. If the interception depth is greater than 0, the rainfall volume will equal (the rainfall depth minus (the interception depth multiplied by the canopy cover fraction)) multiplied by the element area. Rainfall intensity on an element, as derived from the precipitation file, is reduced by the canopy cover fraction of that element until the interception depth multiplied by the canopy cover fraction is reached, at which point the rainfall intensity returns to an unmodified value as derived from the precipitation file.

Here are a few examples you could plug into a spreadsheet or calculator to see how things work.

example 1

precipitation file depth = 20 mm

element 1 area = 1 hectare

element 1 canopy cover fraction  = 0

element 1 interception depth = 3 mm

element 1 precipitation (m^3) on the element = (20 mm - (3 mm * 0) * 1 meter/1000 mm) * 1 ha * 10000 m^2/1 ha = 200 m^3

example 2

precipitation file depth = 20 mm

element 2 area = 1 hectare

element 2 canopy cover fraction  = 0.25

element 2 interception depth = 3 mm

element 2 precipitation (m^3) on the element = (20 mm - (3 mm * 0.25) * 1 meter/1000 mm) * 1 ha * 10000 m^2/1 ha = 192.5 m^3

example 3

precipitation file depth = 20 mm

element 3 area = 1 hectare

element 3 canopy cover fraction  = 1

element 3 interception depth = 3 mm

element 3 precipitation (m^3) on the element = (20 mm - (3 mm * 1) * 1 meter/1000 mm) * 1 ha * 10000 m^2/1 ha = 170 m^3

example 4

precipitation file depth = 20 mm

element 4 area = 1 hectare

element 4 canopy cover fraction  = 1

element 4 interception depth = 0 mm

element 4 precipitation (m^3) on the element = (20 mm - (0 mm * 1) * 1 meter/1000 mm) * 1 ha * 10000 m^2/1 ha = 200 m^3

Shea

[Amit Kallush]

Thank you very much for the response!

Indeed I found the K2 group, but since there are no conversations there, I guessed it's not active.

First of all, I didn't explain myself correctly about the rainfall. My original question was not about the OUT file but the SIM output for a specific element, e.g., "PLANE_211.SIM".

I understand your explanation about the OUT rainfall value, but something is still wired in mine. Let's take, for example, element 211:

precipitation file depth = 1.07 mm

element 211 area = 1356919.12 m^2 (I took the value from the OUT file)

element 211 canopy cover fraction = 0.974

element 211 interception depth = 0 mm

Therefore, rainfall volume should equal rainfall depth times the element area:

1.07 mm * (1 mm/1000 m) * 1356919.12 m^2 = 1451.9 m^3.

But the OUT files show a value of 23245.137 m^3.

As for my original questions about the SIM file, it comes up because of a weird phenomenon in the first two rows. All of my SIM files start with some large amount of rainfall in the first two time steps (6.2 mm in the case of the PLANE_211.SIM file) that I have no idea where they come from.

After 10 min, the rainfall data drops down to reasonable values.

I guess those problems (of the rainfall volume of the OUT file and the exaggerated value in the first two rows of the SIM files) are somehow related.

I am adding here the PAR, PRE OUT, and SIM files. If you could please take a look at that, I would be very grateful,

Thank you very much again,

Amit

ב-יום שלישי, 7 בפברואר 2023 בשעה 20:32:09 UTC+2, Shea כתב/ה:

[Shea]

I looked at your parameter file and noticed the Y coordinate of each element is written in scientific notation, which K2 will not read correctly. Try writing out the full number and see if that addresses the weird output.

Also, an alternative method to use distributed precipitation is to assign the rain gage ID to the element that you want to receive the rainfall instead of using the coordinates of the elements and the raingages. For example, to assign gage 211 to plane 211, between BEGIN PLANE and END PLANE of plane 211, add RAINGAGE = 211, or whatever the associated ID of the raingage is.

Shea

[Amit Kallush]

That was it!

Changing the Y coordinate notation seems to solve the problem, It also completely changes the simulation output, but I guess this makes sense. 

Thank you very much Shea! 

ב-יום חמישי, 16 בפברואר 2023 בשעה 23:58:36 UTC+2, Shea כתב/ה: