Green Roofs

[gusbacos]

Used parameters

StorageMin (and max as it is the same in NonVeg)

Minimum water storage capacity for upper surfaces (i.e. canopy). What is the unit for this parameter?

DrainageEq In the SUEWS Manual, drainage eq = 3 is recommended but I do not fully understand where to look for reasonable values here. I have tried finding Falk and Niemczynowicz (1978), but with no luck. Also what is the unit of drainage coef2?

[sunt05]

I need to do a bit research on these as well.

for storage, their unit should mm. but let me double-check all these and update us here.

[sunt05]

The most recent literature giving related parameters might be this one J11 (see table 2 and eqn 19).

[gusbacos]

Hi,

I have a question on reducing the soil depth when modelling the green roof:

At the moment, i set the soil depth of 100, soilstore capacity to 40and saturated hydraulic conductivity to 0.0066138. However, in reality adding green roof would rather add more soil and soil depth to the building?

so this is what i conceptually see as difference from reality to what I do in SuPy:

Thus, QE gets lower as there are less available water that can be stored beneath the building. Is it thus more reasonable to add more soil, instead of reducing?

Oskar

[sunt05]

Nice schematic 👍🏼

However, please bear in mind that given SUEWS doesn't have a decent green roof module yet, we are in fact using the following structure (clipped from your schematic 😉 ) to mimic green roofs:

And you concern about decreased QE is understandable while in reality green roofs do hold less water due to the shallower soil layer compared the ground lawn. So I'm not surprised by the lower QE and actually that's what we would expect; while to maintain the evapotranspiration, one usually needs to apply some irrigation if the evaporative cooling is more demanding over other GR functionalities (stormwater retention, etc.)

[gusbacos]

Thanks, great feedback!

Great sorting out my worries about QE. I´ll try irrigate the roofs for comparison.

Heads up for coming questions!

[julced]

Hi,

I'm struggling to get irrigation to work for the green roofs and I don't see any changes when I run SuPy after putting in the new settings.

The following changes have been made in siteselect:

• IrrFr_Bldgs change to 1
• IrrigationCode set to 1 (from suews_irrigation)
• WaterUseProfAutoWD and WaterUseProfAutoWE set to 12 (from suews_profiles)

In suews_irrigation I have changed:

• InternalWaterUse to 20
• Faut to 1

Would really appreciate some input on what I'm doing wrong. Thank you!

Julia

[julced]

SUEWS_Irrigation.txt SUEWS_Profiles.txt SUEWS_SiteSelect.txt

[sunt05]

(just had a quick look at your files but didn't do any testing) you have three lines in the site select file while you had only set one line for irrigation:

[sunt05]

and, as I recall, we are using grass as the proxy type for mimicking green roofs; hence I don't understand why irrigation would be applied to buildings.

[gusbacos]

We are at the moment using building as to mimic green roof. I believe that it was we agreed upon to be reasonable when we had our first discussion ( it might be so that it was at one of the meetings when you were not there! ). I think this also brings some clarity to my previous concerns about modelling Green Roofs here above!

So at the moment what we done is to increase the water storage capacity, changed albedo/emissivity/drainage building in NonVeg, and changes in soistorecapacity and sathydraulic conductivity in Soil. And then used a 100% GreenRoof building and a 0% Greenroof building and blend them using weighted averages of the output of a SuPy run.

But if we were to use Grass as proxy instead of buildings, we would need to "blend" the results using weighted averages differently than we do now i assume.

So if we have following scenarios:

a) grass = 100% regular Grass (base scenario all buildings are buildings and grass is grass) b) grass = 100% Green Roof grass properties - no water flow to Grass in gridwithin dist?

I am not sure how to blend these, as more 50% a) and 50% b) means that no vegetation is "added", thus reducing the amount of vegetation (with less soilstorecapacity) instead of increasing them.

Maybe we need to rethink our strategy.

[sunt05]

Ok, I see your thoughts. I think you might need to rethink about the strategy and it might be more helpful if you can set up a notebook for prototyping it. then I can join you there to put my thoughts in code/equations.

[gusbacos]

Ok, great. We´ll do that next week. I need to fix some things before taking Easter holiday.

Have a nice Easter !