Eagle Creek Fire, Erosion and the Resilient Landscape

My name is Diane Hopster and I’m a
hydrologist for the Columbia River Gorge National Scenic Area and the Mount Hood
National Forest. I also worked as a hydrologist on the Burned Area Emergency
Response team or the BAER team. A BAER team is a team that gets together with a
lot of different disciplines like engineering, hydrology ,wildlife biology,
fisheries biology, soil scientists. They get together and they assess the fire
after it’s mostly out, to look at what kind of emergency response activities
need to be implemented and a lot of it is focused on reducing erosion and
preventing any major landslides or debris flows. Post fire erosion is
determined by combination of climate topography including slope surface rock
armoring needle caster litter fall and fire severity/ The Eagle Creek FIre area
has two kind of distinct soil types that we see there’s the very rocky talus
slope terrain, and then there’s these more well-developed soils. In the rocky
talus slope we have a lot of surface rock armoring which actually helps
reduce erosion, though pre-fire a lot of these slopes were covered in moss that
kind of held the rock together and then after the fire in the high burn severity
areas on these talus slopes that moss burned away so it did result in over
steepened slopes and we did see localized rock sliding and we may
continue to see that until the moss regrows. In the well developed soil areas
we’re actually finding some natural revegetation of native plants as well as
some fungal mats that are kind of binding the soil together. Due to the
very steep terrain and the inaccessibility of most of the Eagle
Creek fire area, and that is in part due to the fact that most of the fire
area was in wilderness, it’s difficult to do a lot of the erosion controls that we
would probably do on areas with a lot more roads that’s more accessible
and not in wilderness areas. As far as the very steep terrain it can cause
safety issues, trees falling, hazard trees things like that, so we don’t like to put
people in that situation. Lucky for us we have a very resilient landscape in the
Eagle Creek Fire area. We’re already seeing a lot of natural revegetation as
well as after the burn there’s a lot of litter fall and debris you can see that
there’s needle cast as well as burned trees that fall over and they add
roughness which actually helps to create like a natural mulch and reduce erosion
itself. Some of the recommendations that the BAER team made for reducing
post-fire erosion on the Eagle Creek Fire included improving drainage on the
few roads within the Eagle Creek Fire area. And by improving drainage, because
roads intercept surface flow they tend to concentrate flow and then it will
create landslides or debris flows, and so by improving the drainage you’re
spreading the flow out and keeping it from concentrating and resulting in
erosion that could go down slope and into stream channels and affect
fisheries down below. There were also a lot of recommendations within the
Multnomah Falls area that gets a lot of people from all over the world. It’s
really important that rock-fall is prevented that either damage the
historic structure there, the Multnomah Falls Lodge, and then also protect the
people that are there to look at the waterfall. The recommendations at the
Multnomah Falls site included what you could call geotextiles they’re basically
Rock catchment fencing, that when rocks do fall down the steep slopes that have
burned ,it’s gonna stop those and then they actually have to be cleaned out on
a regular basis. Here is a good example of a steep slope that we see in the Eagle
Creek Fire area, it’s not really a safe place to go and try to plant anything.
But you can see that the fire burns like in these mosaics so that vegetation that
didn’t burn can then spread to the area where it did burn and that helps with
revegetation as well. Erosion can be a very natural process for example when we have fine sediments erode down the slope and into the stream they deposit in
floodplains and then are quickly colonized by vegetation native
vegetation like willows and cottonwoods and things like that that actually
stabilize the channel so fine sediments can be a very good thing and natural
processes can affect and improve water quality sometimes. When erosion is caused by non natural processes is when we get more than the system can handle and
that’s why we focus some of our recommendations on things like the road
where it’s unnaturally concentrating flows that could then erode downslope
and add more sediment than the system can necessarily handle. Right now we look at the landscape and we see a lot of black charred soils, not a lot of
vegetation but ultimately in the spring we’ll probably start seeing a lot of
little green sprouts coming on this hill slope vegetation that can handle this
type of environment will start growing and then ultimately once it has
established then new vegetation will move in and ultimately we’ll end up with
the native vegetation and the type of forest and environment we had before the
fire and the ecosystem here is able to basically regenerate itself it knows
better than we do how to get back to the state it was in prior to the fire.

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