So I have been worried about all the tile drainage that has been going on lately. For those who aren't familiar , a grid of perforated pipe is laid down 2.5 to 4 feet below the surface and all excess water is drained off. I have one neighbor that is doing 8,000 acres this year. ( that would be a strip a mile wide and over 12 miles long ). There are 10s of thousands of acres being drained. There has always been concerns about the quality of the water if it is just piped into ditches but my concern is our aquifers not being replenished. When I have brought it up with pro tiling guys I am always told that water from that level has no effect on aquifers.BUT that doesn't seem logical to me. So I finally quit being lazy and started to try and find info on it.So I found a White paper done in Minnesota. It involved a platoon of PhDs, geologists, Proffs, water resource people....... and here is an excerpt from that study :
Knowledge gaps.
Several critical knowledge gaps are identified in this
paper, creating opportunities for further research
to improve our understanding for better managed
water resources:
1. Extent of drainage is unknown. Direct
estimates of the extent of subsurface drainage do
not exist in Minnesota. However, several indirect
methods have been utilized to estimate subsur-
face drainage, from the field-scale to county-
level through the use of geographic information
system (GIS) analysis and aerial photography.
Based on a 2012 U.S. Geological Survey estimate
of subsurface drainage extent (Nakagaki and
Wieczorek, 2016), about 21% of the land area in
Minnesota has some density of subsurface drain-
age.
2. Effect of drainage on underlying aquifers is
unknown. A basic understanding of unconfined
and confined aquifers and their recharge is nec-
essary to connect any hydrological effects from
agricultural drainage to groundwater. The basic
goal of subsurface drainage to efficiently drain
saturated soils clearly alters the water balance in
croplands. However, its overall effect on ground-
water resources has been poorly characterized,
and is in large part determined by the geology
below drained areas and the arrangement of
underlying aquifers.
3. Water balance shifts. An improved understand-
ing of historical water balance shifts from pre- to
post-drainage periods is necessary to understand
long-term implications on net groundwater re-
charge. Also, more direct field-scale studies and
indirect modeling studies are needed to charac-
terize water budgets for fields with subsurface
drainage.
So they conclude they don't know how much drainage there is. They don't know the effect on aquifers or the recharge of those aquifers. They don't know the long term effect of that drainage.
Yet we continue full bore at it. This is F ing nuts. And know one seems to notice. And most people have no clue it's happening.
