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When to swale and when not to swale?  RSS feed

 
Bret Glassett
Posts: 14
Location: Grass Valley, CA
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Hi All,

Just reading though Brand Lancaster's books (1&2) and I am interested to know more about when to and when not to use swales. He dones't seem to say tough I am guessing the reason being is that "It Depends". Who has more information on any general conditions when assessing a site or region to determine if swales are an option?

For example, here in the Sierra in Northern CA, we have heavy rains/snow Nov - April and then the rest of the year is dry. How would swales preform in this climate? Obviously soil plays a part here but in the grand scheme of rain patterns any thoughts / experiences?


Thanks!
 
Chris Meador
Posts: 38
Location: San Diego County, CA (9a) ~15-18"precip/yr
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I am in a similar boat in back country San Diego County, of course we get less rain and it is warmer. I am always thinking about whether to swale or not. In a class with Brad we did talk about this and the general answer of course was "it depends," but I think what we came up with is that if you follow what his book outlines, thinking about the slope you are trying to work with (you don't want a swale on a slope that is greater of 2:1, terraces are for slopes greater than that), then just be sure when you build the swale to size it appropriately (including thinking about soil type, make sure you have done a peculation test) and build in overflows. All that stuff is in the book as you know, but I think what he said in the end is to start small and experiment.

So the way I am going to do it, eventually, is just put in minimal effort and build one relatively short appropriately-sized swale, overflow, something to cover the bare soil and see how it works. Then I have not put in too much time/effort, I can easily adjust if necessary and see what the results are. Depending on what I find, I may put in more, but at least I have a reference and something easy to experiment with.
 
Chris Meador
Posts: 38
Location: San Diego County, CA (9a) ~15-18"precip/yr
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Also, here is a related recent post if you didn't see it already, http://www.permies.com/t/44661/earthworks/Swale-Swale
 
Bret Glassett
Posts: 14
Location: Grass Valley, CA
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Thanks Chris - that video is exactly what got me thinking about this as he does say he gets rain only part of the year it made me wonder if it was just that reason that he decided not to swale or a host of others (such as there being no run off).

My property has several swales I dug recently and a moderate grade 2.5:1 or so and I have noticed (after doing 3 of the swales) that much of the rainwater does not run on the slopes as it has natural mulch and that most of the runoff comes from the hardpack areas. I suppose time will tell what they do.
 
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