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Possible water planning tool?  RSS feed

 
Topher Belknap
Posts: 205
Location: Midcoast Maine (zone 5b)
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I was drifting off to sleep listening to the rain, and thinking about permaculture and the local botanical gardens, and I had a dream.

I dreamed that I had a version of Sketchup that would calculate the water flow over a landscape. The botanical gardens had some severe water erosion problems a few years ago, and still has a lot of water running over impervious surfaces. So, I could go into Sketchup, get the topography of the area from Google maps, and have it calculate the flow rate of water. For some value of soak rate for the ground, this could determine what rain rate would produce runoff, where it would be, and how much in any particular place. Now Google maps has a very general idea of topography, so fine details would not be visible, but the general outlook might be discernible.

Is this available somewhere? Is this something anyone other than me would use? Should I do a Kickstarter? Does someone else want to do a Kickstarter (and give me a copy)?
 
Jennifer Wadsworth
Posts: 2679
Location: Phoenix, AZ (9b)
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Hi Topher:

Just for clarification for myself - what end goals are you trying to achieve with the calculations above? For instance - are you trying to curb erosive activity? Harvest water? Redirect water away from something?

Are you simply looking for an automated tool or do you want to know if other calculations are available for whatever end goal you have in mind?
 
Topher Belknap
Posts: 205
Location: Midcoast Maine (zone 5b)
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Jennifer Wadsworth wrote:Just for clarification for myself - what end goals are you trying to achieve with the calculations above?


I want to do permaculture. Geoff, Paul, Bill all talk about controlling water as a primary goal. For me, controlling something requires understanding it. Being a Mathematician, understanding it, means knowing the math, and then (being a software engineer) getting someone/thing else to do the work.

In one permaculture video, I recently watched, Ben Falk,was amazed that the hurricane he was experiencing hadn't washed away his farm. Quite frankly, being amazed means he didn't know how his earthworks would respond to a large water flow (while not implying in any way that he is less than perfect). And this is someone who knows enough about water to build those earthworks in the first place.

Some things that such a piece of software might do:
1) Convince people who are skeptical of permaculture that it is a scientific endeavor, and can present hard numbers to back up its recommendations.
2) Show a landowner where they will be experiencing washout volumes and rates of water.
3) Help determine how a swale system will work before the work begins.
4) Help determine possible locations for ponds etc.
5) Calculate the holding capacity of a pond.
6) Help determine how much of a particular rainfall ends up in the ground and how much flows through the property.
7) More things, I am sure those more conversant with permaculture might think of.

But I wasn't thinking of this for just myself, my question was to ask if there is a crying need for such a thing in the permaculture community.

Thank You Kindly,
Topher
 
Jennifer Wadsworth
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Location: Phoenix, AZ (9b)
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Topher Belknap wrote:
In one permaculture video, I recently watched, Ben Falk,was amazed that the hurricane he was experiencing hadn't washed away his farm. Quite frankly, being amazed means he didn't know how his earthworks would respond to a large water flow (while not implying in any way that he is less than perfect). And this is someone who knows enough about water to build those earthworks in the first place.


I can only speak to what we do here in the desert SW with our soil types and rain patterns. While there probably is modeling software out there that does this, it's not accessible to me (but there are some folks I can ask!)

If I was to build earthworks I would first figure out the square footage of my watershed, and determine the type of surface(s) involved (figure out square footages for each surface). Surface type will give you what your runoff coefficient is. For example, an asphalt roof's runoff coefficient is 0.9 and bare soil (in our location) is 0.4. In your location, your bare soil coefficient could be very different. There are also other coefficients for other surface types (vegetated, forested, etc).

So then the calculation becomes ____ sq ft x _____ inches of rainfall x 0.623 gal/(in x square ft) x ______ runoff coefficient = net runoff.

The inches of rain can be calculated for an average rain (in Phoenix we use a 1 inch rain) or for a 100 year storm event (amount of water that falls within 60 mins in our 100 year rains). In Phoenix this is 2". When you get into humid areas these numbers are vastly different. Most earthworks are sized for 100 year events. Because of a number of factors, earthworks in dryland areas tend to need greater capacity than those in humid climates.

Topher Belknap wrote:Some things that such a piece of software might do:
1) Convince people who are skeptical of permaculture that it is a scientific endeavor, and can present hard numbers to back up its recommendations.
2) Show a landowner where they will be experiencing washout volumes and rates of water.
3) Help determine how a swale system will work before the work begins.
4) Help determine possible locations for ponds etc.
5) Calculate the holding capacity of a pond.
6) Help determine how much of a particular rainfall ends up in the ground and how much flows through the property.
7) More things, I am sure those more conversant with permaculture might think of.

But I wasn't thinking of this for just myself, my question was to ask if there is a crying need for such a thing in the permaculture community.


It's an interesting line of inquiry and more visual tools would help people understand earthworks better - no doubt about that.
 
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