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so there you have it the why where and
how of building and designing
permaculture ponds
raise your hand if you love ponds
i think ponds just have exceptional
value in the permaculture landscape and
really benefit the ecosystem and
hydrology of an area
now ponds can also be a total disaster
and a hazard when put in the wrong place
in the wrong climate and built the wrong
way so make sure you watch this video
all the way through so you don't build a
disaster this is a really complicated
design process and it can be really
tricky to figure out the why
where and how to build a water body so
i'm going to walk you through the
thought process for designing a pond and
we'll start with
why
now some people build ponds in the
permaculture landscape just to slow the
water flow within the watershed and get
water to seep into the ground and build
the underground water table so this pond
in a way is like a beaver dam where
water moves through the pond but is not
held tight
the pond is actually meant to seep so a
pond seeps water if it's not sealed or
lined in some way
a lot depends on the soil type and if
there's enough clay content in the soil
if that soil has been compacted
now i saw many examples of seepage ponds
hand dug in my travels in india that you
can see in the footage
from this linked video
multiple seepage ponds placed throughout
the landscape can literally recharge and
rebuild the underground aquifer of a
whole area now because a seepage pond
has uncompacted soil
the embankment itself
doesn't really hold back water so it
shouldn't be planned as a structural
feature
seepage ponds are really excellent for
restoring springs that can pop up below
the pond because of the moving
underground water and they can actually
sub irrigate crops below them so the
plants are passively watered by the
underground seeping pond water the next
pond type we're going to look at now is
specifically meant for irrigation
rain-fed irrigation ponds will collect
water but then that water will be
emptied during the growing season to
irrigate crops so irrigation ponds
should be sealed as well as possible to
save water and if they can't be sealed
by compaction
then they should be lined water from an
irrigation pond will need to be
distributed into an irrigation system of
some sort and most commonly people use
either a lock pipe going right through
the dam wall or a siphon to get the
water out of the pond in a controlled
way now because the water is being used
for watering crops then a rain-fed
irrigation pond will be empty by the end
of a dry season however a recreation
pond wants to stay full through the warm
season for swimming and other fun and it
wants to have a gradual slope on all
sides so people can get in and out
easily and safely with a shallow end for
children now another pond that wants to
stay full all throughout an entire dry
season is a fire fighting pond so the
water in a fire fighting pond needs to
be able to be released from the pond in
the event of a fire to either flood some
sort of fire containment line
feed a fire hose or pressurized
sprinklers but often in a fire the
electricity goes out so a fire fighting
pond needs to be able to gravity feed a
firefighting system without electricity
this means it has to be placed in a
higher position within the landscape now
i've also seen where a fire fighting
pond is designed that's big enough for a
fire fighting helicopter to actually
land in forested areas next we're going
to look at the habitat pond now a
habitat pond wants to have varied depths
and edges for lots of different habitat
niches now it should also have natural
seasonal fluctuations of the water level
so different niches are available during
wet and dry periods
now from the permaculture perspective a
lot of different yields can be built
into a habitat pond and it can be
integrated with the harvest of aquatic
plants waterfowl and fish
but for more intensive fish production
we have the aquaculture pond an
aquaculture pond is a more controlled
environment where the inflow and the
outflow of water are managed to maintain
the water level and it's also designed
in a way that facilitates the harvest of
the species being raised
now aquaculture ponds around the world
are mostly found in wet lowlands where
watery landscapes are transformed into
managed production systems but an
aquaculture pond can also be in the
system as an irrigation source where all
of the nutrient-filled water can be
applied to crops
so as you can see
a lot depends on where a pond sits
within the overall water system
is there a continual water source to
fill ponds like a spring or a creek
or do they depend on rainfall
the really important thing to realize is
that a pond doesn't just fall into one
of these categories for example you can
have a recreation pond that's also a
fire fighting pond because both of these
uses require that water is maintained
throughout the summer but you cannot
have a fire fighting pond that's also an
irrigation pond because the irrigation
pond will be empty during the dry season
as water is applied to crops so in
permaculture we work to create as many
uses and yields from every element so
how many uses can a single pond provide
i mean the design is only limited by the
creativity of the designer so how many
connections can you make how about a
habitat pond that also seeps water and
benefits the hydrology while raising
ducts and providing fertilized water for
irrigation
the limit is your own imagination
so
this is a general sense of the why
and now
let's talk about
the where
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so let's start by looking at where on
the slope you place a pond in relation
to its storage efficiency at the high
point of a slope at the top of a hill
water can be stored in a pond for a high
supply
to gravity feed the areas below but
without any runoff flowing into it from
anywhere on the landscape so it would
need to be filled somehow from below so
as big of a hole as you're able to carve
out is as much water that you can store
if you have the right soil type and
don't hit a shallow bedrock when you dig
then as you go down the slope
from steeper to more gentle slopes so
you can see that the ratio of the amount
of soil moved
versus the amount of water stored
increases as you go down to the flatter
part of the slope so the flatter the
area
the more water that can be stored for
the amount of soil that's moved but at
the same time the higher up in the
landscape that you can store water then
you have the potential to move that
water down using gravity for supply of
areas down below without using
electricity so you need to choose the
landscape positioning carefully and the
truth is you'll typically find much
better soils for building ponds lower
down the landscape profile
so the soils may make the decision for
you about where to put a pond another
big consideration is placing the pond in
or off of the channel now this is a
contour map so looking down on the land
from above
this is a valley
where the water is flowing through
and this here is an adjacent ridge so
you can place a pond in the channel
where the water is flowing which has its
benefits and liabilities
now on the plus side the area already
has water flowing through and it can
have a really high efficient ratio of
soil moved to water stored
if placed in a gentle landform but on
the minus side this is where the force
of water is concentrating so in flood
conditions
all of the force of water is flowing in
this spot in the valley so the structure
right the dam the water holding
structure needs to be planned with a
strong overflow spillway to handle
large and historic level of flood events
additionally
many government permitting agencies in
various locations don't really like
in-channel ponds because they can
disrupt habitat like fish movement and
wetland displacement so in-general ponds
are often frowned upon by regulatory
agencies
and off channel ponds are usually more
beloved by regulators now in an
off-channel pond you'd create some sort
of diversion from the channel itself or
from roads or surface runoff to feed
water to a pond on a ridge location so a
ridge location is a more stable location
because it's not in the path of a flood
it may require more soil movement and
thus have a lower storage efficiency
these are just a couple of
considerations of the wear and i go much
more into specific pond types and their
placement within the landscape in my
key line in the augmented reality
sandbox series linked right here in that
series we discuss the various types of
ponds positioned within the landscape so
check out that series and now we're
going to deal with
the how
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pond design usually starts by drawing a
cross section so you'll need to figure
out what your embankment looks like and
where the soil will come from to build
it
so where is the water actually coming
from again i would direct you to my
series key line in the augmented reality
sandbox linked to here to talk about
pond positioning and water sources
so once you have an idea of what you
want to do you'll need to dig test pits
and see what the soil composition is at
different depths to see where you have
enough clay content if you're creating a
pond to hold water
here's another great video link that
shows this process right here
so this hole right here is called the
boro pit and its slope is typically not
steeper than three to one
that means three horizontal units to one
vertical unit because a machine has to
drive in
and out to excavate and move the soil so
if you're doing this by hand then you
could do whatever slope you want as long
as it stays stable
typically the inside slope of the dam
wall itself here
is no steeper than two to one
and the outside slope
is no steeper than three to one so you
can see that you need to do some
geometry to make sure you have enough
soil in here and enough room to build
this whole structure
then you can calculate how much water
the pond will hold see the water level
can't come all the way up to the top of
the dam
because when there's a strong wind then
the water can actually splash over the
top and degrade the structure so you
need to give several feet or about one
meter of free board which is the space
between the top of the dam and the water
level now depending on the soil type you
may need to make a clay core when you
build the dam and anchor that clay core
into the ground with what we call a key
trench this is to make sure that water
doesn't seep through the dam wall and
then and that the dam is actually
anchored into the ground
then the most typical ways that water is
taken by gravity out of the pond is
through a pipe that actually goes
through the dam called a lock pipe or a
siphon that's pressurized and goes over
the dam so a lot of the world over
people just use gasoline pumps stuck in
the water to get the water out of the
ponds
so these are the bones of the ponds
but how can we make this whole system
more dynamic so we can do all sorts of
design to create plant niches different
levels put trees on the edge the dam
itself can even be planted but not with
trees or woody perennials because a
tree's roots can work their way through
the pond and create pathways for water
to leak through so let's look at this
pond from above because there's another
super crucial piece that if it's not
done right can spell disaster as we
discussed before every pond needs a
spillway
for overflow water when the pond is full
so this spillway is the place where the
water overflows from the pond when it's
full
and the size of that spillway needs to
be related to the amount of water
flowing into that dam during flood
events one way to do a spillway is a
wide grass channel where water will flow
around the dam
but it's best to put what's called
a trickle pipe that's a bit lower in
elevation than the spillway which is a
pipe that takes the normal overflow of
water from the pond not during floods
and pipes it down below the dam this
means that most of the time the spillway
itself does not have flowing water
through it but remains vegetated or clad
with rock and only has water flowing
during high flow events when the trickle
pipe is overwhelmed
so the vegetation or the rock cladding
protects the spillway so it doesn't
erode during flood events but it's
stable at that time
conventionally a lot of times
people just put a culvert through the
dam wall for a spillway but the thing
about a culvert is it has a fixed
diameter and this doesn't allow for a
historic level flood event that might
overwhelm the culvert and blow out the
dam
so a wide grassed or rock clad spillway
has a lot more capacity for that
unexpectedly massive volume of water
that you get during a flood event
another type of overflow channel
and the spillway is to actually have the
water overflow
from one pond through an on contour
swale that's connected to another pond
so this way these two ponds are actually
connected and fill simultaneously where
the swale actually extends the holding
capacity of the ponds when full
now another type of spillway for a pond
with a connected swale is called a level
sill spillway where the overflow water
goes over this wide level plane so the
water is spread out evenly over the sill
and flows in a sheet over the edge
ideally hydrating a dry ridge below
wherever these overflow waters are
directed to that overflow should be
treated as a resource and the receiving
structure should be engineered to handle
flood events
so this pond could also overflow gently
downslope
to another pond so now we have three
ponds and they're all connected and
their embankments here the tops of the
dams can actually function as a road and
a roadway can be can connect all these
three ponds so these water structures
become the bones of the system
and then the vegetation layer is
overlaid on top of this
main frame structure of roadways and
water collections
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so getting the water design established
in a permaculture system creates the
foundation for all the other layers and
so figuring out
the why
where
and how of a pond can be a crucial piece
for your design of the whole site now
i've got to say
i've just barely scratched the surface
here and i may have just given you
enough information to be dangerous
there's so much more to say about ponds
that if you're going to design or build
a pond it's really imperative that you
do more research than what i've
presented here i've placed links in the
video description down below to some
really good resources including darren
doherty's regrearian's handbook and
katie nelson's design and construction
of small earth dams
so good luck out there and together we
can restore the hydrology and ecosystems
of this beautiful world and feed
ourselves at the same time
so there you have it the why where and
how of building and designing
permaculture ponds
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you