hi my name is Mary Ellen Summerlin and
this is what we call our aquafer model
actually it's a model simplified of the
whole water cycle we see a cloud the
surface of the Earth a lake a river
Wells underground and many layers of
rocks sand clay and gravel deep under
the surface of the
Earth aquifers are just those layers
that hold water and allow water to pass
through them the layers that don't hold
water don't let water pass through are
called
aquitards this model can show us
something very important about water on
our planet it's a closed system every
bit of water we have now is water we've
always had there's no such thing as new
water
the water we'll drink today is the water
dinosaurs drank millions of years ago
every drop on the planet is at some
stage of this water cycle it's
evaporating condensing and precipitating
evaporating precipitating over and over
recycling itself
forever aquafer water which is in
storage under the ground enters this
cycle when it discharges through Springs
into streams rivers lakes and then can
evaporate into the sky or when we pull
it up through Wells and use it and then
it can evaporate then it can condense
and precipitate with the rest of the
rain when rain falls lots of it runs off
the surface of the Earth into the lakes
and streams but some of it percolates
down through the sub the top
soil into the aquifers and recharges
them so we have recharge and discharge
of the aqua
as part of this whole cycle we see that
surface water and aquafer water are
really all the same water constantly
recycling part of our finite water
cycle in Kirk county we have lots of
aquafers they have names like Fort
terret and Hensel and Cow Creek and we
have a few aquat tars like the
Hammet as in the model they're made of
different materials and the water in
them is different in quality quality
some very good for drinking some not so
good now water in the aquifers is always
moving water in our model is clear so
I'm going to add a little color to it so
that you can see the
movement more
dramatically I think you're going to
notice two
things one
is that water moves at very different
speeds in different aquafer
the other observation is that the water
all moves in the same
direction this in in both respects the
model is reflecting Kirk
county water moves under uh on the
surface water moves downhill we all know
that underground we talk about water
moving from areas of high pressure to
areas of lower pressure in the model
this is the high pressure side this is
the low pressure side so that's why all
the water runs that way in Kirk county
the water in our aquifers generally runs
from Northwest to Southeast but we can
always count on water we'll see this
again and again in the demonstration it
always moves from a place of higher
pressure to a place of lower
pressure a big difference between the
model and the aquafer is this Stone
aquifer this rock aquifer in the model
it's on the bottom
in real life in Kirk county it's up here
on the top right under the grass and the
top soil in fact some places it sticks
out through the grass and the top and
the top soil as we all know we call it
the Edwards Plateau
aquafer we group our aqu we've grouped
our aquafers together for easy reference
one group we call the Edwards Plateau
another the upper the middle and the
lower Trinity aquifers all of them refer
to many layers
ERS these Rock layers that are right up
at the top in Kirk county
are an abundant source of
Springs they furnish ranch homes their
Wells livestock
tanks but most
importantly they furnish and support the
guadalupi river the guadalupi river in
this county is the source of irrigation
the source of Industry source of our
Recreation and Camp businesses and the
drinking water for the city of kville so
you can see that this Edwards aquafer is
very important to our
County now this um uh Rock Limestone kst
aquafer extends far past our borders for
thousands of acres to the north and
west that means that when it rains north
and west of our us this wonderful
aquafer that moves water as you saw
rather quickly is all coming our way and
that's why when we had our drought that
lasted several years and all the rain
seemed to miss KK County the river never
went dry it was feeding off all that
rain water that fell north and west of
us and moved our way through the Edwards
aquafer or the Edwards Plateau aquafer
we want to make a distinction between
the Edwards Plateau aquafer and the
Edwards balcone fault Zone aquafer what
we short call for short the Edwards
bfz that is a part of the aquafer that
is downfaulted
3,000 ft and under the city of of San
Antonio for example has resulted in
giant caves full of water even divers
have been in them we think in Kirk
county our Edwards Plateau aquafer looks
more like this model that is smaller
pass ways through the rocks and little
pools but very rich in water for
us droughts and floods are very common
in our region when we have floods the
rain comes too fast and everything fills
up the Lakes fill up the
rivers the
reservoirs sometimes the rivers even do
damage with the heavy
water when the
surface features fill up so does the
aquifer and the water
rises in the various aquifers and in the
wells in
them when the rain stops and droughts
happen then the water levels recede we
can see it obviously on the
surface and even underground we notice
that the aqua for levels as reflected in
their Wells drop
down we need to think of our aquafers as
our savings account for water they can
help us level out these natural
fluctuations of rain flood and
drought but we have to remember to keep
enough water in
reserve during times when the river is
low or when demand exceeds what the city
is allowed to is permitted to withdraw
from the river the city of kville relies
on Wells in the lower and middle Trinity
aquifers these are extremely rich
aquifers in our County and support all
the big commercial Wells the ones that
might be used for industrial purposes or
for um water supply companies private
water supplies that that Supply
household water to many households there
are also some residential wells in these
aquifers this
model does a good job of showing us how
wells
work water fills a well because the
pressure in the aquafer is higher than
the pressure in the wellbore in fact
from the model just as in real life you
can see that the water the pressure is
so much higher in the aqua that the
water rises above the top of the
aquafer and that's what happens in real
life too now a pump works on the same
Principle as a drinking straw we draw
the air out of that pipe and the water
rushes in to take its place when we pump
our well we may notice that the well the
water level drops a little bit but
pretty soon it comes right back to where
it was that's because we can depend on
water moving from a place of high
pressure to a place of low pressure
it'll always do that I'm going to pump
this well again but this time I want you
to look at well number seven a well
that's also in the same bottom aquafer
in the model when I pump well
one you
noticed that the water dropped in well
7 this is called the interference of
Wells the well with a big pump will draw
the water from its cone of
depression all around it actually taking
water out of other
Wells one of the most important
functions of the local groundwater
conservation districts in Texas like
Headwaters in Kirk county is to um um
regulate the spacing of wells and the
size of pumps so that this interference
does not cause
trouble another very important function
of the groundwater conservation
districts is to Monitor and um limit how
much total water we withd draw from our
aquafers this is very important because
aquifers can actually be
depleted now it sounds like water is
always coming in and always going out so
how could an aquafer
deplete that makes sense until you think
about pumping and the speed at which we
withdraw it there have been age dating
studies done in Kirk county that show
that the water in the Trinity aquifers
is very old as old as 20,000 years that
means it has moved in here very very
slowly we believe that it does not
recharge from rainfall in Kirk county
but Moves In from around
us if we pump faster than the new water
is coming in we can actually use up that
aquafer and for all practical purposes
deplete it our wells won't work
anymore so it's very important for us to
keep that in mind in fact um we have
records of Wells that go back to the
1970s and have been continuously
monitored since that time and they show
a steady a slow but a steady decline in
the level of water in our Trinity
aquifers going forward as our population
continues to increase we're all going to
have to remember and adjust to this hard
fact aquafers like bank accounts can be
used
up naturally when since we live in a
semi-arid place it's smart to conserve
water all year round rainwater
harvesting is a great idea the city of
kville uses another wonderful Innovative
idea that you can visualize very well
from the model in wintertime the city is
allowed to treat water from the river
that is in excess of what is actually
demanded by the citizens of kville
because they're not doing any outside
watering to speak of so the extra water
is inserted in what are called ASR Wells
aquafer storage and Recovery Wells
actual Wells into the lower Trinity
aquifers that insert treated river water
then in
summertime when demand is high sometimes
doubles when people begin to water their
yards all the time that water which has
hardly moved at all in this slow moving
aquifer is available recognizable
because it's chlorinated and available
to be drawn back up and used to meet the
demand a very good
system I want to show you one more thing
with the aquafer model and that's how
aquafers can become
polluted now they're underground you
would think they would be protected from
pollution but think about underground
storage tanks the kind maybe in under
gas stations not supposed to leak but
they might think about septic systems
that are maybe not so well engineered or
too close
together they can
leak sometimes s just lazy citizens who
instead of properly disposing of
herbicides and pesticides and automobile
fluids and paint decide to just dump it
on the
ground very soon we see that
pollution sinking into the aquifer and
don't forget here it's that fast moving
car Stocker that's on top and which way
is it going right to our River the
source of our drinking water we need to
be very very careful about polluting our
aquafers water is essential to every
aspect of our lives our health our
economy agriculture industry energy
production technology and the Very
balance of nature on which all life
depends wherever you live find out where
your water comes from and commit
yourself to protecting this vital
natural resource thank
you