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Hi Again, July 13, 2012
I got off on a tangent, in my previous post, and forgot to comment on
the weather so far this growing season.
Given a good soil, about 6" of available water in the upper metre
(enough for about 6 weeks of evapotranspiration in the NE), deep rooted
established perennial crops such as apple can readily go for a month without
rain or a full growing season if roots go down to 3-4 metres.
I have noticed that growth of most established plants this year is
unusually rank; i.e. trees, lawn 'weeds', grass and even annual plants have
grown will water or care. Our typical spring and early summer often has too
much water; leaching of nutrients from the rooting zone and poor aeration.
But Ash trees, both in the yard and in the woods seem stressed this year;
not disease or insects just indifferent foliage and ragged growth.
Yt, DW, Kentville
----- Original Message -----
From: "David & Alison Webster" <dwebster@glinx.com>
To: <naturens@chebucto.ns.ca>
Sent: Friday, July 13, 2012 6:57 PM
Subject: Re: [NatureNS] Freshwater Shortages and Bay of Fundy Tides
> Hi Patricia & All, July 13, 2012
> I don't know Greg Gerrits but I do know Elmridge Farm produce; top
> quality and this implies unusually good management. So I would be inclined
> to accept his observation of well replenishment rates as a function of
> something to do with tides but it can not caused directly by height of
> saltwater in the 'nearby' shore.
>
> Flow of any liquid in a porous medium is directly proportional to
> hydraulic gradient (head z/lateral displacement y) and inversely
> proportional to resistance. A head difference of 10m over lateral
> displacement of 10 km (hydraulic gradient = 0.001) would induce
> essentially zero flow Or approaching this from the other direction, when
> water is pumped exhaustively from a well the water table (drawing on
> memory) is seldom lowered beyond a radius of 50 metres.
>
> I would suspect that a tidal effect leads to a local artificial
> hydraulic gradient. In effect, water running uphill to the well (and well
> vicinity) during this peak inflow period.
>
> I ran into NatureNS by accident some years ago while trying to find
> some understandable explanation of tidal effects on the internet. The
> nearest I have come to an explanation was some oracular comment to the
> effect that it is explained by math that almost no one understands. But
> meanwhile the tides come in and go even though I don't understand how it
> works.
>
> YT, Dave Webster, Kentville
> ----- Original Message -----
> From: "P.L. Chalmers" <plchalmers@ns.sympatico.ca>
> To: "NatureNS" <naturens@chebucto.ns.ca>
> Sent: Friday, July 13, 2012 2:28 PM
> Subject: [NatureNS] Freshwater Shortages and Bay of Fundy Tides
>
>
>> For most of my life, my family home in Bedford was dependant on a drilled
>> artesian well, as there was no municipal water supply in our
>> neighbourhood. This is no longer the case, but I am still acutely aware
>> of how valuable water is, and curious about hydrology. I was in the
>> Annapolis Valley last week and saw how very dry the fields and orchards
>> were there. So last Saturday, at the Halifax Seaport Farmers' Market, I
>> was asking some of the farmers how they were getting on in the present
>> drought.
>>
>> I had an interesting chat with Greg Gerrits of Elmridge Farm. Since
>> there was so little snow last winter, and since it was such a dry spring,
>> his normal water supply is down at least 40% from normal levels. He
>> doesn't have enough water to irrigate more than a few acres at a time.
>> However, he went on to explain the influence of the Bay of Fundy tides on
>> his water supply. He said that the weight of incoming water in the Bay
>> was sufficient to exert pressure on water deep below the ground, even
>> where he farms (near Sheffield Mills, I think). The flow of fresh water
>> into his well improves significantly when the Bay is full of salt water.
>> So he has learned to schedule his irrigation so that it begins three
>> hours before high tide, and stops three hours after high tide.
>>
>> There are so many kinds of knowledge that a successful farmer needs to
>> have, but it hadn't occurred to me that a knowledge of the tides was one
>> of them. I may not be representing this very well, but I found it
>> intriguing; perhaps someone could say more?
>>
>> Patricia L. Chalmers
>> Halifax
>>
>>
>>
>>
>> -----
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>>
>
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