Al Rea... get started.
This is Al Rea,
and this is the National
Hydrography Advisory Call.
Today we've got
Jay Stevens with us
from the Bureau
of Land Management
in the Oregon-Washington office,
and before we get started,
I do have a quick announcement
to make regarding
our staffing.
Our co-lead, my co-lead,
Becci Anderson, is back.
She has decided
to come back to USGS,
and she's back
in her old job.
So I'm really happy about that
to have her and have her back
and really appreciate
all the hard work
that Steve Aichele put in
as acting in that position
while she was gone.
So we're really,
really happy to have Becci back.
I think Steve is happiest
of all to have her back,
but I'm pretty happy too.
So anyway, just wanted to give
you that quick announcement,
and now I think we'll go ahead
and turn it over here
to Jay Stevens,
and he can take it away.
Go ahead, Jay.
Jay Stevens Okay.
Well, thanks for inviting me
to talk with you all today.
So I'm Jay Stevens.
I'm a GIS Specialist
in Portland, Oregon,
working for the Bureau
of Land Management,
and we've been experimenting
with delineating
NHD and WBD from our good lidar
that we have in Western Oregon
for probably about
4 or 5 years now,
but we're definitely ramping up
our efforts right now
to really try to get
most of Western Oregon
covered with new
lidar-derived NHD and WBD,
and we're working
with other agencies.
We're not the only agency
that has an interest
in getting this work done.
We're working with
the Forest Service,
the Oregon Department
of Forestry,
Oregon Department of Geology
and Mineral Industries, NRCS,
but I'm going to kind of
give you guys
the BLM view of things
and kind of go over
how we got into this business
in the first place,
what our business requirements
are and sort of
how our process has evolved
and how we're doing
our interagency
collaboration on this.
So let me start by,
I'll show this.
This is a map of Oregon
showing the ownership pattern,
and the boundary
that you're looking at
is the boundary of
the BLM's Western Oregon plan.
Most of the activity that's
happening in Western Oregon
as far as land management goes,
it's really centered
around timber harvest.
So there's some of
the most productive
timbered lands in the world.
They're in Western Oregon.
It's a pretty wet place
in the coast range.
The precipitation covered
by this plan area ranges
from somewhere around
10 inches of rain down here
to about 200 inches of rain in
parts of the coast range here.
So it's quite a varied terrain,
but our basic goals
for our plan are,
besides producing
a sustained yield of timber
to counties that depend
on timber receipt,
we have quite a few species
of endangered salmon here.
So if you look
at the distribution
of specifically listed
species of salmon,
it covers quite a bit
of the area
of our Western Oregon plan,
and our management prescriptions
here are pretty restrictive
and very specific.
Our primary concerns as far
as the health of salmon goes
is going to be stream
temperature and turbidity,
and the way that we preserve
the health
of these aquatic ecosystems
is to make sure that we have
a good riparian buffer
around the stream networks.
So there's an area where
we really don't do anything.
We don't harvest any timber
within 120 feet from a stream
and in the outer edges
where do commercial thinning
in the very outer edge,
but even on intermittent
streams,
we have quite a bit
of protection here.
So when we're planning
a potential timber sale,
like this shows
an example of ...
The red area on the map
would be areas
where we could be
harvesting timber,
and, of course, the blue
is showing the riparian buffers.
The black lines are revised NHD
after deriving flowlines
from lidar, doing fieldwork.
That really changes the picture
of what's actually accessible
in terms of timber harvest.
So that has a major impact
on our planning.
This is our definition
of intermittent stream.
Really evidence of annual scour
and deposition
with well-defined bed
and banks within
a continuous channel network.
So that covers quite a bit
and particularly
in the coast range.
I'll show an example
of what the NHD looked like
on top
of the yellow 10-meter DEM,
and the kind of changes
that are possible,
the kind of changes
that become evident
when you can see through
that heavy conifer canopy
and see what's actually
on the ground.
So this can have a really
profound impact on our ability
to estimate what we have
available in terms of timber
and what we need
to be protecting.
So I'm showing here,
this is the availability
of high-quality
lidar-derived DEMs
that's available
in Western Oregon,
and this covers most of the
BLM's ownership in this area.
So obviously it's a lot
of ground to cover.
It's an expensive proposition
to get this work done,
so we had to go to management
and explain that,
"Hey, we have a wide variety
in density here
that needs to be corrected.
Obviously most of our stream
channels that are mapped
are not in the right spot,
so we really need
to get to work on this,
and rather be doing it
incrementally
through the spotty field work
that's done,
it would be much more efficient
to just go ahead
and get this done by delineating
entire 12-digit units."
So we were able
to get some funding
to kind of ramp things up
and hire some contractors
who were able to do modeling
work and editing work,
and so we can have a goal now
to get all the work done
where we have BLM ownership,
where we at least have some
BLM ownership
in a HUC in Western Oregon
and then work with
the other agencies
to really get all of this area
done regardless of the ownership
and do that by engaging
the hydrologists
that we have working
in our various field offices
and resource areas
to make sure
we get review of the work
before it goes into the NHD.
So as I mentioned, we've been
working on our techniques
to do this delineation
for quite a while,
but this is a workflow that
we're basically using right now.
We are resampling
the DEM to 3 meter
just to make the processing
faster and applying the filter,
the fancy filter
that Paola Passalacqua
advocates in her research.
So we've borrowed pretty heavily
from Passalacqua's research
and some of the open-source
Python-based
code that's published.
So we're using both curvature
and flow accumulation
as kind of a basic filter
to identify
the channel skeleton,
and so we have a rough draft
of the linework
from curvature
and flow accumulation.
Then we do quite a bit of work
with clean up
and hydro-enforcement,
incorporating whatever
field data
we can get from hydrologists
that have done work out
in the field,
and then actually have
the hydrologists review and mark
up our draft delineation
and do our final delineation
based on that,
estimate the periodicity,
go over the imagery
and the lidar
and straighten out
all the waterbodies and areas,
do the actual NHD update,
deal with whatever data we had
that was attached to the NHD,
which in our case we have
a lot of fish distribution data
that's referenced to the NHD
that we actively use the HEM
tools to manage our events.
So when the NHD changes
under that,
we have to go back
and synchronize
all that data
to the new line work,
and finally we also need
to do the WBD.
So generally the WBD
is easier to do
once we already have
the flowlines in place.
So here, I'm just showing
an example of what happens
when you resample
and filter the 1-meter DEM.
You don't lose a lot.
We're finding that
we're not losing
a significant amount of detail
in terms of what it takes to get
channel location accurate,
and we do benefit
from the filtering
in that it's a little bit easier
to get the streams
to get across the roads
without having to do
hydro-enforcement,
so it saves us
a little time on that,
but mostly processing time.
So with this resampled DEM,
resampled and filtered DEM,
we can look at geometric
curvature and flow accumulation
and come up with basically
what we call a skeleton
of potential channels.
The green is
the flow accumulation,
and the red is the curvature.
So both of those conditions
have to be met
to have a stream initiation.
So just having, say, 2
or 3 acres of curvature up here,
that's not enough
to initiate a channel.
There actually has to be
some evidence of a channel
based on the curvature
for us to delineate.
So from that skeleton,
we identify that ...
We thin the skeleton
and locate the end points.
So these end points,
even if it's just
a couple of pixels
that meet that criteria,
that could be an initiation
point for a channel
and used on the least-cost path,
we would trace to the pour point
and create our initial network.
But of course that still results
in a number
of spurious channels,
and it still requires
some visual interpretation
to adjust the initiation points,
take out the channels that we
don't think should be there,
particularly in these
flatter areas.
There's quite a bit to clean up.
So generally using slope,
hill shade.
Also we've been making extensive
use of topographic position
index to do this visualization
work and cleanup work,
but we've also started using
TPI more as a filter
to sort of automate
that cleanup.
So I'm going to show
an example
of how our process
is evolving a little bit here.
So we're looking at sort
of a problem area
where there's local curvature
here in this flood plain,
and there's adequate
flow accumulation for channels
to be delineated there,
but really these are
kind of spurious channels
that we would take out.
But experimenting with
the topographic position index,
we can apply this
as an additional filter,
and you see that some of those
spurious channels aren't there
because we're requiring
that the topographic position
index threshold also be met
for the channel to initiate.
So once we've got
our basic network,
we still have a bunch
of hydro-enforcement to do.
This example shows cases
where despite the filtering,
we still are having problems
with channels
running along
the roadside ditch
before they get to
where they need to go.
So we're just doing basic
drawing enforcement lines
and just burning these into DEM
and saving our breaklines.
So these are
pretty straightforward.
As we get to working in areas
where we have more
anthropogenic disturbance,
particularly
the agricultural areas
we're having to do
a lot more work
to get these streams
across farmers' fields
following imagery and evidence
of ditch features
and the DEM
and doing quite a bit of
this kind of hydro-enforcement
along the way.
Now, sometimes,
when we're lucky,
we actually have a decent amount
of field-collected data
from our hydrologists
that are out there
planning timber sales
and restoration work
and getting out there and
locating these initiation points
or intermittent streams,
and this is just an example
that's showing
where we had quite
a bit of that data,
and in that case
we'll just go ahead
and use that information
to adjust the network
before we even give it
to the hydrologists to review.
So this example is showing
the initiation points in green,
and then these are locations
or culverts in red,
and this information can also
be used for us to adjust,
basically looking at a few
examples, head water locations,
we can adjust
our curvature threshold
that we use
or flow accumulation threshold
that we use
for general initiation
to get the model more calibrated
to the field data that we have.
So once we have our final ...
Al Rea: Say, Jay.
Jay Stevens: Sure.
Al Rea: Yeah, I got a question
on that last slide.
Jay Stevens: Mm-hmm.
Al Rea: So you have quite a few
culverts there, the red marks,
where there's not
a channel indicated.
Jay Stevens: Right.
Al Rea:You don't require there
to be a channel for a culvert,
or just how
do you handle that?
Jay Stevens: Well, it's kind of
tricky business
with the culverts
because they are ...
Let's look at an example here.
These are going to be
cross-drains.
So they don't necessarily
indicate a stream crossing,
but they might just be
for basically handling storm
drainage along the ditch.
So it's kind of a tough call.
Some of them do represent
stream crossings,
and some of them don't,
and usually there is
some information
that the engineer that went out
and drove the road will indicate
whether it's a cross-drain
or if it's a stream crossing.
And sometimes they even have
some notes about periodicity
or whether there's water or not.
So we do use that information.
Al Rea Okay. Thanks.
Jay Stevens Yeah.
So once we have
our final stream network ...
Or actually,
I shouldn't say final.
We've done
our hydro-enforcement.
We're ready for the hydrologist
to do his final markup on it.
In the cases where we don't have
field data for periodicity,
we are using Shreve stream order
to estimate the periodicity.
So the Shreve stream order
is different from Strahler.
It's just a straight
additive stream order.
So I think in this case
it's going to be
a stream order of five.
It just adds up the tribs.
So it's kind of
a better proxy for flow,
and we didn't want
the periodicity breaks
to be in the middle
of a flowline
unless we actually had
field data indicating that.
So that's what we're using
for our basic estimate
of periodicity.
So we developed a web app
for hydrologists
to review line work,
and we've tried to make it
as simple as possible
for them to do that.
If they want to bring
the inception point down,
they'll just put
a yellow point
where they want the adjusted
initiation point to be.
If they want to get rid
of the trib entirely,
they'll put a red X where
they can add an inception point
or a periodicity transition.
If they want to actually
reroute something,
they can draw lines
to add and delete.
So that's working pretty well.
We support this either in an MXD
or the web app,
and we also can make this
available for external partners
to do the same review.
So once this review is done,
then we can take these
adjusted initiation points
and basically just by pushing
the points around
and redelineating
using least-cost path again,
now we have our final
stream network
that's ready for the NHD.
So we'd pass this on
to our editors to go ahead
and start getting this
into the NHD,
but the editors have
some other work to do.
Doing any modeling from a DEM
doesn't include diversions.
We're modeling
a dendritic network,
so if there are features,
particularly when we get
into the dryer areas
and we're dealing
with irrigation,
these have to be added
in by hand.
So we're trying
to definitely make sure
that important irrigation
features are included.
Other work that the editors
are doing is,
they're scanning
over the imagery and making sure
that all the waterbodies
are digitized correctly
and also reshaping
the NHD area features.
So this is showing an example
of an NHD area feature
that's been reshaped,
probably looking at contours
and looking at the lidar,
looking at the imagery
and coming up
with a better double-line stream
to represent this river.
One problem that we've had here
is that if the DEM hasn't been
hydro-flattened,
then you're going to have
a pretty erratic path
that gets modeled through
this wider channel,
and really, it's pretty
meaningless information
because this isn't
the green lidar.
It doesn't penetrate water,
so really, the meandering
within this channel
is just pretty much random.
So what we're starting to do
is if we really see this,
and it's messy,
we're just starting to do
some basic hydro-enforcement
along these wider rivers.
So that's what we've done
in this case.
The yellow line is showing
the hydro-enforced line.
So one of the major difficulties
in doing the NHD editing here
is that we need to preserve
the reachcodes,
and we need to preserve,
basically,
reachcodes and GNIS names,
and we need to preserve
reachcodes in the cases
where we have fish
distribution information
because we have
multiple agencies
that are referencing
these reachcodes
just to attach
linear events to the NHD.
So when we're going in here
to do these edits,
we're making sure that we do
a geometry replacement
while saving all the attributes
on these reaches.
And for the major streams
and major fish-bearing streams,
it's usually
pretty straightforward.
There's not
super radical differences
in the geometry here,
but we do have the occasional
difficult situation
where it's debatable
whether to save the reachcode
because like in this example,
this stream
basically doesn't exist.
It actually goes this way,
and there's a bunch
of conflicting reachcodes.
So that's kind of part
of the difficulty of editing
is deciding what to save
and what to throw out.
For all the minor tribs,
we're not saving
the reachcodes,
and that's mostly
because with the lidar-based
delineating,
there's really not enough
spatial coincidence
that I feel like
it's really worth the effort
to save those reachcodes.
So some of the subbasins
in Western Oregon
have a lot of flowline.
So we have subbasins that have
100,000 flowlines in them,
and running the QC
on the regular NHD update tools
has been a really
time-consuming task,
and it's really kind of extended
the time
that it takes for us
to do edits.
I wish there was a way
to do kind of isolate
the editing
just down to a six-field HUC,
but at any rate, the tools
are working pretty well,
and they've been getting
good support from our POC,
and it is working,
but it is a pretty slow process.
So now I'll touch
a little bit on the WBD.
Now, our WBD boundaries
are in pretty decent shape,
so the change has generally been
pretty small,
but we do occasionally
run into situations like this
where obviously this drainage
belongs in this HUC,
not in this one.
You can see where
the error originates here,
and I'd like to be able
to just say,
"Let's just model this
and use this line,"
but as with the NHD modeling,
with the WBD modeling you also
have interference
from roads, et cetera.
So you can see how this kind of
got messed up by this road.
So we're going to have
to go back
and stick to the contours
to really straighten this out,
but I think the modeling is
pretty effective for ridgelines
where there aren't any roads.
So in this case,
we'd probably just go ahead
and use that modeled line
and maybe generalize it
a tiny bit, but just use that.
So I want to focus
a little bit on:
One of the benefits
of doing this work
is that for each of these HUCs,
we now have a lot of data.
We have our DEM clicked out
to the watershed.
We've got a hydro-enforced DEM
and flow accumulation,
cost distance,
and we've got data
that's ready to do
other kinds of modeling work.
So one of the projects
that's come up recently for me
is starting to look
at prioritizing road restoration
or culvert replacement.
So it's been kind of exciting
because in the past
because the flowlines aren't
accurately mapped to the DEM,
and now we have good flowlines,
I can actually identify
where the road
stream crossings are exactly,
and I can delineate catchments
and collect statistics
about this catchment.
I can take the original
1-meter DEM
that was not hydro-enforced,
and this example
is showing depressions
that I'm capturing
from the 1-meter unenforced DEM,
so I can calculate things
like fill volume
and fill depth
behind this culvert.
So we can identify places
that are at higher risk
of culvert failure
and road blowout
that could deliver large amounts
of sediment to this stream here,
which happens
to contain multiple
endangered species of salmon.
So this is going to be
really helpful for us
to further our efforts
to protect the fish.
So one of the complications
I'm going to move on
to talk a little bit about,
the interagency collaboration
piece here:
With this kind of complicated
ownership pattern,
I'm showing an example of ...
Let's see, in this HUC,
I've got BLM ownership.
I've got
Oregon Department of Forestry.
I've got Forest Service.
We got some
tribal lands down here.
The ownership pattern is crazy
in Western Oregon.
Private land,
private timber land here.
So there's a lot of stakeholders
within one particular HUC.
So in order
to coordinate this effort,
we've had to develop
an application
just to track
everybody's progress,
track what everybody is doing.
So I'm going to try to get
this thing out of the way here.
Okay.
So this is showing the status
of our delineation efforts,
what's complete,
what's in-progress,
various stages of progress
and what's planned
for this year.
So we've got multiple agencies
involved. So I can do ...
This app is going to let me
do things
like look at which ones are BLM,
which ones are Forest
Service HUCs,
Department of Forestry.
So a lot of the times, we're
working in close proximity,
and certainly working within
the same subbasin,
which is the unit
of transaction or checkout.
So this is helping a lot
because all the agencies
that are involved
in the effort have the ability
to go into this app
and edit
the HUC polygons
and keep everybody else informed
as to what's happening there.
So we're tracking
that both for the NHD
and also for the WBD progress.
Oh, whoops.
I was going to try to go back
to my last slide here,
but I think I can go ahead
and take some questions.
attendee:Is the markup tool
being used for this
or just
a general bulk conflation?
Jay StevensThe markup tool?
attendeeYes, sir.
Is that what's being used
to edit the NHD,
or is it just a bulk conflation?
Jay StevensWe're using the NHD
update tool.
attendeeOkay, thank you.
>> The regular editing tool.
We have experimented with
the conflation tool in the past.
Al ReaSo, Jay, I think he was
asking about the USGS markup,
the web markup tool
that we have.
It's kind of a new thing.
Jay StevensRight, right.
There has been some use
of that here,
and I think we're still
sorting out how to process
updates from that,
but the markup tool
that we're using is specifically
designed to markup
the lidar delineation.
But to the question
of the conflation tool,
I think if the conflation tool
had the ability
to do partial conflation,
in other words, if I could say,
"Okay,
for this list of reachcodes,
I want to do conflation,"
I think the tool would be,
for our specific project,
it would be more useful to us
if we could do that.
Al ReaSo there was a question
asked through the chat,
"Did you use any kind
of automation
to delineate waterbodies?"
Jay StevensNo,
we haven't done that.
Basically we're just scanning
through
by tile,
just looking at the imagery,
looking at
the existing water bodies,
using a combination of imagery
and looking at the lidar
to identify new waterbodies,
but if there were techniques
that are being used for that,
I'd definitely be
curious to know.
Al ReaSo ...
attendeeIs there a direct ...
Sorry.
Al ReaNo, go ahead.
attendeeIs there a direct
transfer of the Shreve stream
order to the NHD feature codes
for perennial intermittent
ephemeral classification?
Jay StevensYeah. In the places
where we're modeling,
the Shreve stream order
that's less than
whatever the threshold is
for that HUC
is going to go into the NHD
as an intermittent stream.
attendeeOh, got you.
Jay StevensYep.
Yeah, we felt like
it was important to have
periodicity on the NHD
even if it's not
all field verified
because I think very little
of it is across the country.
Al ReaRight. So you're using
different thresholds
in different HUCs
or different areas?
Jay StevensYep.
We are because we have
such a variety in precipitation,
and then we're also
getting feedback
from different hydrologists
that are working in the areas
that they work in.
So basically, we're doing
a consultation
with the hydrologists
to determine,
what's the best threshold
for that particular HUC
given the soils
and precipitation and so on?
Al ReaSo, Jay, I noticed you
talked a web review tool
that your hydrologists use
that you showed that.
Jay StevensUh-huh.
Al ReaThey use that
in the field,
like on a handheld unit,
or is it just in the office?
Or ...
Jay StevensWell, they're not.
I think that theoretically,
they could.
We do have some applications
that we've been rolling out
where hydrologists are using
a mobile app
to collect
stream-initiation points,
but generally
they would do that ...
If they have that information,
they would give that to us
as we begin the delineation.
Al ReaMm-hmm.
Other questions?
attendeeAl, I've got a question.
You guys have pretty
good relief out there,
but I'm curious what you do
or what happened
with the lidar data
when you call the roads
or whatever is in the way of
the streams, digital-type dams.
How did you bust
through that in the lidar?
Jay StevensJust drawing.
Basically the hydro-enforcement
technique is very simple.
It's just ...
I'm trying to get back to the
slide here to show an example.
Backwards again.
So in this case, just to look
at an example right here,
it would take this line
and find the minimum elevation
on this line
and make all
the elevation values
equal to the minimum elevation.
So it's basically a trench.
It's digging a trench
in the DEM.
Al ReaSo you put those lines
in manually?
Jay StevensWe put those lines
in manually.
Al ReaOkay.
Jay StevensWe have experimented
with some automation on that.
One way to do that is
to basically identify the sink,
then identify the lowest point
in the sink,
and then go in a radius
out from that
and find the next pixel
that is a lower value
than the center of the sink.
We have used that technique,
and that works pretty well,
but we still have to go through
and identify the ones,
the sinks that we actually
want to do that on.
So by the time you do that,
you might as well
just draw a line.
Al ReaMm-hmm.
Jay StevensSo we're kind of just
picking the technique
that's the quickest to get
the job done the fastest.
attendeeSo a question here.
This is Sean Vaughn
from Minnesota.
Is a culvert there
at those locations,
or is there not a culvert
in those examples
just used on-screen
with the red lines?
Jay StevensWell,
I would speculate
that the vast majority
of situations,
there's a culvert,
but we don't know that.
We don't always know that.
That's what we're assuming.
So there could be. There's
certainly room for error.
attendeeYeah. It just seems
to me like you've relied heavily
on a lot of input
from hydrologists,
which I think is
incredibly important
in a process like this.
Jay StevensMm-hmm.
attendeeA task I would
put upon them
is identifying
where the culverts are.
We do a lot of similar work
here in Minnesota.
Jay StevensRight.
attendeeAnd our value is
on the culvert,
and then putting what we call
a digital dam breach line
where the culvert exists.
And then from there our process
is similar to yours ...
Jay StevensRight.
attendee...
lowering the lidar-obtained
elevation values ...
Jay StevensYep.
attendee... to the minimum value
of where that culvert is.
Jay StevensRight.
attendeeWhat we then get
is a more in-sync thought as
to where our flow paths
are now in sync with real-world
locations
of where culverts are,
and it brings reliability
and credibility to our work
for hydrologists as well
as end users of the product.
Jay StevensRight.
Well, certainly, in the areas
where we actually have
culvert data,
we'll bring that up and use it,
and even in that case,
if the culvert data
was collected
before GPSs were out there
or before
the GPS accuracy was good,
sometimes they're actually
pretty far off.
So we're having to look
at that data and say,
"Okay, is this culvert
actually here,
or should we look
at the sink in the DEM
and put the culvert there or put
the hydro-enforcement line
where it actually makes sense
on the DEM?"
So it really varies a lot,
and unfortunately because we're
doing all the ownership ...
We're not just doing
the BLM streams.
We're doing the entire HUC,
so a lot of times
the BLM ownership
is only 20 percent
of the HUC or less.
So we don't have any data
for the rest of the HUC.
attendeeI had a question, Jay,
about whether you overlaid it
with your 1-meter
and how well it matches since
you're developing the lines
off of the 3-meter?
Jay StevensRight.
Well, one thing
that the 3-meter
combined with the filtering
that we're doing,
it's going to take out
some of the small ditches
on the edges of the road,
and that's actually a good thing
for just getting the stream
delineation done
because you'll have
more circumstances
where if you had
a really small sink here,
the stream will actually just go
straight across the road,
and you don't
have to burn it in.
So as I was showing ...
Let's see.
I'm going to show my ...
With this slide,
what I'm showing
is these that I'm showing
in red actually have ...
I have depressions thematically
displayed by still depth.
I'm deriving these
from the 1-meter DEM
that hasn't been hydro-enforced.
So I do think
that that information
is really helpful
to have and to keep,
especially if you are doing
this kind of analysis,
which is basically,
I'm trying to identify
the potential for a backup
on the other side of the road.
So with the 3-meter DEM,
no, I'm not going to get that.
I've lost some of that detail,
but again,
I can go back to the 1-meter DEM
and extract that if I want to,
which I did want to do
for this particular application.
attendeeI had one other question
about your reach codes.
You said that some
of the reach codes
you weren't transferring over.
Are those just getting lost
and assigned new ones
when you're doing the update?
Jay StevensYep.
attendeeOkay.
Jay StevensYeah.
I think, to go back to this kind
of radical example here,
not all ...
This example is
in the coast range
where the trees are probably
200 feet tall,
and you would never see ...
The original method
of compiling,
the original 24K maps,
you'd never see the ground.
Yeah, I think the problem is
that for just with this stream,
for example,
if you were going to say,
"Okay, I want to save
the reach code for this."
The question is, well,
is it this stream
or is it this stream?
Is there really a point?
At this point, I don't feel like
there's any benefit
to save the reach code there,
but for ...
Go ahead.
I'm sorry.
attendeeI was going to ask if
you try and overlay your events
and try to save those
in particular.
Jay StevensExactly. Yeah.
What we would do is say,
"Okay, we've got
multiple agencies
have fish
distribution information
that's attached to this stream.
We want to save that."
And we're definitely
saving the reach codes
where there's
a GNIS name, too.
So if there's a GNIS name,
definitely saving
the reach code.
If there's fish distribution,
definitely saving
the reach code,
but for the vast majority,
no, we're not going to
try to figure out
which one of these streams
belong to this original line.
And I think that's why ...
Like I said, I think we'd be
using the conflation tool
if there was ...
If the conflation tool could do
a partial conflation and say,
"Okay, I know that we want
to conflate this line,
but we're not going
to do these."
I'd love to figure out a process
that would be more efficient
to get that work done.
Al ReaSo there was a question
from the chat,
"Are you working to
a particular specification
for positional accuracy?"
Jay StevensWell, that's kind
of a tough question.
I guess not
really consciously.
I think the level
of positional accuracy,
looking at this slide again,
we're working within pretty ...
These are kind of distances
that are really important to us.
Resampling the DEM
from 1 meter to 3 meters
while it's not ideal
that we're doing that.
It's kind of a compromise
to improve the performance
of all the modeling software
and the ability
to get the work done,
but we don't feel like
we're losing
a lot of positional accuracy
by doing that.
So positional accuracy
is really important
because we really need to know
where these buffers are
and how this is going to effect
our planning for timber sales.
Al ReaBut I think what
you're saying
is that the positional accuracy
you're after
is quite a bit larger
than 1 meter or 3, even.
Jay StevensWell, I'd say
the 3-meter
would be where we want to be.
Al ReaMm-hmm.
Any more questions?
This has been
really great, Jay.
We definitely will want
to pick your brains
some more about this as we ...
We're in the midst
of developing specifications
for lidar-derived hydro.
Jay StevensUh-huh.
Al ReaAnd I think we'll
definitely want to loop you
in at some point to take
a look at at we've got.
Jay StevensYep.
Well, I think ...
attendeeIs this call
being recorded?
Al ReaIt is, yes.
Yeah, so if
you want the link ...
If anyone on the call
wants a link to the recording,
let me know.
I don't know that
we'll be able to put it
on our website or anything
because there are a lot
of requirements there,
but I'll share it
if you send me an e-mail.
attendeeOne last question, Jay.
Are you doing anything
with the culvert break lines
that you digitized?
Jay StevensPardon me?
attendeeAre you doing anything
with the culvert break lines
that you use to enforce
with the hydro-enforcement?
Jay StevensWell, we're
definitely saving them
so that we can reproduce
the stream delineation,
and we're saving
the hydro-enforced DEM.
So, yeah, this is definitely
part of our project data
that we're going to keep.
Al ReaYeah, actually, Jay,
looking at that list,
I was very curious.
Are you sharing any of this,
or you're keeping it on file,
or what's the status?
Jay StevensYeah, we're building
out some data structures
to handle this.
We're kind of debating
whether to mosaic
some of this stuff together.
This is a little bit
of a work-in-progress, too,
but this is basically
what we're saving right now
along
with a little bit of metadata,
recording the edits that
the editors made to water bodies
in the areas and other flowlines
that they digitized,
the draft initiation points.
So ... Whoops.
So that we know,
what did the model predict
versus what was the final based
on everybody's review?
So we felt like those
were important things to keep.
But, yes,
the breaklines are key.
attendeeAre you finding
any trends
comparing your model initiation
points versus the fielder
and the field information
that you get from hydrologists?
Jay StevensWe haven't done
any large kind of meta-analysis
of how we're doing there.
We generally eyeball things
when we start on a HUC.
We just tweak the parameters
of the model
so that it matches
the initiation points
if we have them.
Otherwise, we're pretty
much reliant
on the expertise
of the hydrologists
to make the refinements,
but I think we will ...
We're actually, now that we're
acquiring quite a bit of data,
I think it's kind of ripe
for that kind of analysis.
attendeeThis is Sean
with Minnesota again.
What you're touching
on now is, I think,
one of the greatest values
to all of us across the country.
This is something we strive
for in Minnesota,
and what I'm getting at is:
When we save point
of initiation,
I think we really tend
to talk about,
where is concentrated
flow forming on the landscape
to a level of ferocity
and velocity
in which it forms erosion.
And lidar is a technology
that identifies
and captures what I call
water-conveyance landforms.
In other words:
Water formed this erosion
and the landforms
captured by lidar.
Jay StevensUh-huh.
attendeeI'm always intrigued
by all of us
in these conversations
about where we model
that point of initiation
and where someone out on
the landscape tends to put it,
and sometimes they just
don't even jive.
Jay StevensRight.
attendeeThey don't match.
Jay StevensRight.
attendeeEarlier in your process
or your presentation,
you mentioned you use TPI,
and that's something
we rely on heavily here.
I actually call it HPI.
In other words, it's using TPI
but to really
identify hydrography.
So hydrographic position index.
Jay StevensRight.
attendeeI would ...
In Minnesota, we tend to see
a greater ability of our HPI/TPI
to identify that point of origin
more so than we could model it,
and more than where someone
could actually be
in the landscape at time
if it's a very shallow bed
and bank definition.
So where I'm going with this
is to say that,
as you write this up,
and this is something I sense
all of us
need to collaborate more on
because it's so critical
and this role of understanding
where does water begin to flow
in the landscape
and how does that relate
to our various definitions of,
what is a water course?
Jay StevensRight. Right.
Yeah. I think in the case
of Western Oregon,
we were able to come up
with a pretty good consensus,
even though this definition
comes right out
of our plan document.
The other agencies involved,
the Oregon Department
of Forestry,
the US Forest Service,
because we're all doing the same
business in Western Oregon
of the timber management and
the protection of the salmon,
we're all kind of
on the same page
in terms of our business
requirements
and therefore on our definition
of a stream,
but this would change, I think,
if we start working
in eastern Oregon,
it's not going to be the same
what people want to see mapped.
I think people are going to want
to see ephemeral draws
that only have water
every couple years, for example,
but this definition
explicitly says
annual scour and deposition.
So, yeah.
I think that's the rub.
What are we mapping?
attendeeYeah, I appreciate
your definition.
I think that works well
in many parts of the country,
certainly here in Minnesota.
It is something that ...
Well, I'll just stop there
for time's sake.
This could go on,
or at least I could go on.
Jay StevensSure, yep.
Al ReaYeah, we are kind of
out of time today,
but we could always
have you back, Jay.
We really appreciate your time
on this and presenting.
Jay StevensSure. Yeah.
Al ReaIt's been
very informative.
So thank you again,
and will you make
your presentation available?
Jay StevensSure. Yep.
Yeah, I can do that.
Do you want me
to just e-mail that to you?
Al ReaSure, yeah, and I'll
put it somewhere
that people can get to.
Jay StevensOkay, and any
other questions
that didn't get answered,
I'm always happy
to have a conversation.
So feel free to shoot me
an e-mail.
Al ReaGreat.
Jay StevensAll right.
Al ReaWell, thanks again, Jay.
Jay StevensYeah, thank you.
It's been great. Good questions.
Al ReaYeah. Thanks, everyone,
for attending.
We'll talk to you again
in about a month. Thank you.
Jay StevensAll right. Take care.
attendeeThanks, Al.
attendeeThank you.
attendeeThank you.
