Hi
This is a question on the approach to take in order to achieve a
consultancy objective.
For two farms I have to give some input on the possible design of a
small water reservoir for agricultural use.
I have this rainfall data: the number of days per month of moderate
rainfall (4-6 mm/hr) of at least 4 hours. So, without taking into
account extreme events, which are more interesting for erosion, I was
thinking of doing a r.sim.water calculation for each month of the water
depth in the reservoirs, and at the same time an evaporation
calculation, to build up a yearly report of the potential changes in
the amount of water available.
Has anyone ever used GRASS for this type of work? Perhaps for dams?
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Perito agrario Enrico Gabrielli
progetto F.A.R.M. www.farm-agroecologia.it
Tessera n. 633 Collegio Periti agrari prov. Di Modena
Biblioteca agricoltura: https://www.zotero.org/groups/aplomb/
https://www.inaturalist.org/observations/bonushenricus
On Wed, 26 Jul 2023, bonushenricus wrote:
This is a question on the approach to take in order to achieve a
consultancy objective. For two farms I have to give some input on the
possible design of a small water reservoir for agricultural use. I have
this rainfall data: the number of days per month of moderate rainfall (4-6
mm/hr) of at least 4 hours. So, without taking into account extreme
events, which are more interesting for erosion, I was thinking of doing a
r.sim.water calculation for each month of the water depth in the
reservoirs, and at the same time an evaporation calculation, to build up a
yearly report of the potential changes in the amount of water available.
Has anyone ever used GRASS for this type of work? Perhaps for dams?
Enrico,
There are a couple of methods used in the US that might be applicable, but I
suggest you look at precipitation records for the past few years in the
region of the two farms. Given the rate of climate heating and the more
frequent strong weather events everywhere any existing ag pond sizing method
is probably no longer valid.
Depending on the purpose of the pond I would find the most extreme
precipitation events (and the antecedent weather conditions) and add a
safety factor to those. It would be better to oversize them (if that could
be done) than have them overfilled.
It's a changed world and we're all guessing how to advise clients to be
prepared for unpredictable, extreme events.
Good luck,
Rich
Tanks Rich
Excellent advice!
I could do both
for example, check with three events, a moderate rain of 5 mm/h x 4
hours, a heavy rain of 15 mm/h for 1 hour, and an extreme event of 50
mm/h for 15 minutes.
And for each event, give a frequency index.
There are all about small slope sides.
Do you have any articles or searchable projects on the internet to
recommend the US method?
In addition, I need to learn how to do earthmoving calculations and
then use 3drasters, so if you have any advice on how to do that, I
welcome it.
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Perito agrario Enrico Gabrielli
progetto F.A.R.M. www.farm-agroecologia.it
Tessera n. 633 Collegio Periti agrari prov. Di Modena
Biblioteca agricoltura: https://www.zotero.org/groups/aplomb/
https://www.inaturalist.org/observations/bonushenricus
On Wed, 26 Jul 2023, bonushenricus wrote:
Do you have any articles or searchable projects on the internet to
recommend the US method?
Enrico,
Since I'm not at all familiar with the area in which you're working I have
no specific suggestions. I did find a web site that summarizes several
models:
<https://stormwater.pca.state.mn.us/index.php/Available_stormwater_models_and_selecting_a_model>\.
I've used TR-20 in the past, but every one of my projects has been different
in terms of location, water quality issue, and regulatory requirements.
In addition, I need to learn how to do earthmoving calculations and then
use 3drasters, so if you have any advice on how to do that, I welcome it.
Not sure I understand your need. I've often worked with hard rock quarry
operators to model topographic changes and storm water flows. The base data
is the smallest scale DEM available for that location which is then modified
as needed. I'm an applied ecologist, an environmental scientist, and neither
an engineer nor a geologist.
You may have to invent your own approach and document what you've done to
demonstrate to non-technical decision-makers why it's both technically sound
and legally defensible. Effectively communicating complex environmental
issues to decision-makers can be the most important and difficult of our
job.
Best of luck,
Rich
On Wed, 26 Jul 2023, Rich Shepard wrote:
Since I'm not at all familiar with the area in which you're working I have
no specific suggestions. I did find a web site that summarizes several
models:
<https://stormwater.pca.state.mn.us/index.php/Available_stormwater_models_and_selecting_a_model>\.
Enrico,
One further thought: that web site makes an important point; you have
different modeling needs depending on what needs to be modeled: hydrology
(input to a receiving water body), hydraulics (in-channel flows), or water
quality. Water quality modeling requires different statistical models
because of the characteristics of water chmistry and biota.
Regards,
Rich
Thanks Rich
I work for small farms.
For their needs and for simplified permit management, I design
irrigation ponds of less than 5,000 m³.
Perhaps Bentley's product or HydroCAD might be suitable, but they are
not available in Linux.
SWAT has just been upgraded to SWAT+, and works in QGIS. But from the
bibliography I found it seems complicated to use for this kind of small
ponds. But maybe I am wrong. I asked the mail-list of SWAT+ users what
they thought.
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Perito agrario Enrico Gabrielli
progetto F.A.R.M. www.farm-agroecologia.it
Tessera n. 633 Collegio Periti agrari prov. Di Modena
Biblioteca agricoltura: https://www.zotero.org/groups/aplomb/
https://www.inaturalist.org/observations/bonushenricus