So, there you have it.
Now you know how to find your watershed
and why that is so important.
Watersheds are the building blocks of Earth's landscapes.
In fact, the entire world
is made up of interlocking watershed basins.
And if you want to know where you really are on the planet,
on Mother Nature's map,
then you need to identify your watershed.
A watershed is a drainage basin.
So, this is a ridge.
And all the water that falls on this side of the ridge
flows down
through this network of drainages.
Now, I can tell this is a ridge
because I'm reading these contour lines.
See, each one of these lines
represents a level plane.
Now, if I go and make a dam at the bottom of this watershed
and fill it with water,
then the water level
will settle out at a contour line.
So, this line here where the water is settling out,
this represents a level line through the landscape.
And each one of these level lines,
each one of these contour lines, is the same thing, right?
So, this ridge top here
is a complete circle,
meaning it's a high point all around this basin.
And all the water that falls on this other side of the ridge here
flows into some other watershed.
So, the ridges, the hilltops, mountaintops
are the dividing lines between different watersheds.
So, when you're finding your own watershed,
you want to look at a topographic map
and put markers on all of the high points.
And then you should be able to connect the surrounding high points
by following these ridges and the saddles between the hills
to make a watershed boundary.
Because every watershed has an unbroken boundary,
which is the dividing line between different watersheds.
So, all of the water inside this line
flows down through this same pattern of branch drainages.
So, the drainage pattern is always like the branches of a tree.
Smaller branches combine into larger branches
as you get lower down in the watershed.
Now, within this larger watershed,
there are also smaller watersheds.
See,
each one of these little smaller drainage basins
surrounded by these ridges
is its own watershed.
Because watersheds are fractals,
meaning it's the same pattern at whatever scale you look at it.
See, this is the watershed right here
that ends in this low spot where these two ridges come together.
So, this is its own little drainage basin,
where all of the land that falls on this side of these ridges
is all going to drain to this location right here.
But even on a smaller level,
this right here is its own little basin.
So, when you talk about the watershed,
it's really a relative term.
So, if my home is right here,
then when I talk about my watershed
for this point right here,
I could be talking about this really localized watershed
that's encompassed by these ridges, this little basin right here.
Or I could be talking about this bigger basin
that my home is within.
Or I could be actually talking about this entire watershed basin,
because I am really part of this greater watershed.
And on and on and up it goes.
We could keep scaling up, right?
The Nile River has its own massive watershed,
as well as the Mississippi and the Amazon.
Those rivers have humongous watershed basins, right?
Vast basins that are made up of lots and lots
of these smaller basins.
And this is how the world is divided up.
So identifying where you sit
within the smaller to bigger to larger watersheds
is really important to understanding the forces at work,
and the forces that you ultimately want to plan for.
For example,
if your house or village is located here,
and then you have a massive rainstorm up here,
then you're at risk of flooding.
So, if this whole upper watershed here is a forest,
then that will help to slow and absorb water
and reduce the risk of flooding.
All those trees help to change the duration,
stop that water flow,
and get it soaked into the ground.
But if these trees are clear cut
or burned up in a fire,
then the water will move much faster through the watershed
and have a much greater flood impact down below.
Because trees, spongy soil, and vegetation in the upper watershed
moderates the pulse of water as it moves down through the watershed.
The same goes for urban growth.
Now, if you have a city,
and then when the city keeps on expanding
and creeping up into the hills,
then you're putting all of the land below that
in the rest of the watershed at greater risk of flooding.
Because the city doesn't absorb water,
all of the hardscape and roads and buildings just further shed water,
and that water moves at a faster speed
down through the watershed
to create more potential destruction below.
So, you can see that understanding where you are
within the dynamic system of a watershed
is vitally important to making wise development choices.
And finding your watershed
is the first step in that process.
So, there you have it.
Now you know how to find your watershed
and why that is so important.