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The Kern River built the South Fork Kern Valley with
sediment eroded from the surrounding mountains as it
meandered across the floodplain for millions of years. In
December 2010 the South Fork Kern River’s channel shifted on
Audubon’s Kern River Preserve. Sediment build up in the
former channel caused floodwater to be diverted, cutting a
new channel across a former farm field and capturing the
river in what used to be an overflow channel. Flooding and
channel migration are part of the natural dynamics of free
flowing rivers. This is a natural event and not a problem
for habitat, wildlife values or for Audubon’s property. In
fact, this event can be considered positive for wildlife and
habitat on the preserve. Flood events such as this
rejuvenate old and create new habitat by jumpstarting the
natural successional processes.
What is unknown is how we will choose to live with this
river going forward. Will we choose to try to tame this
river and confine it or will we build over it and let nature
run its course?
The new river channel brings most of the river flow to
Sierra Way roadbed as it crosses the floodplain about 0.3
miles south of the bridge and former channel. The culverts
currently in place at this portion of the road will not be
sufficient to carry future flood flows and may not be able
to pass spring flow. As a result this road is damaged and
will remain closed for the foreseeable future.
Kern County is taking the lead to develop a work plan for
the short term to clear debris and sediment and improve the
flow of water towards the existing bridge. But over the long
run regular channel clearing is not the best environmental
outcome and may not be the most economical solution.
An elevated causeway, or series of passages under the road,
is a long-term solution that will increase capacity for
future flood flows and prevent the river from washing out
the road. This would also allow the river to flow naturally
and wildlife to pass underneath.
Audubon is committed to working with Kern County and our
neighbors to develop a solution based upon a cost benefit
analysis, the best engineering approach, an understanding of
floodplain geomorphology, damage to property and
environmental concerns.
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From the air on you can see how the new channel braids
through pasture lands and then pools above Sierra Way
Road. The bridge and old channel are on hidden by the
forest up against the hillside on the right. Prince
Pond, South Fork Wildlife Area and
Lake
Isabella are seen below
Sierra Way Road. 21 January 2011.
Image courtesy Reed Tollefson. |
Mary
Whitfield surveys the newly discovered channel that cut
across the former Colt Pasture during the December
storm. 7 January 2011.
Image courtesy John Stanek. |
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Looking
upstream from the former Colt Pasture nature trail on 8
January 2011.
Image courtesy Alison Sheehey. |
You can see
the westside of the Colt Pasture nature trail now
completely cutoff on 8 January 2011.
Image courtesy Alison Sheehey. |
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Looking
downstream one can see the water levels remain high on
11 March 2011.
Image courtesy Alison Sheehey. |
The water
made a clean cut across Colt Pasture nature trail road
as seen on 8 January 2011.
Image courtesy Alison Sheehey. |
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The river
jumped its banks and sought out a low lying over-flow
channel making it the new main channel. This now directs
water to Sierra Way Road about 0.3 miles south of the
bridge. 8 January 2011.
Image courtesy Alison Sheehey. |
The
capacity for water to pass under Sierra Way Road is
insufficient causing a large pool to form above it on
the Hafenfeld Ranch and Kern River Preserve. This
flooding is damaging to the road and reduces the value
of the pasture to the rancher. 17 March 2011.
Image courtesy Alison Sheehey. |
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A map of the new channel along with
the existing channel that still carries some water but
less than before the flood. Map by Sean Rowe © Audubon. |
Information Resources for the Kern River
Valley
North Fork Kern River data
South Fork River flow and stage
- click event to get table of all data - click flow, stage to
see chart
California mountain highway website.
Local state highways - 178 and 155
CHP road
website - select Bakersfield - click media information
Kern County road closures
Recollections from the Big Flood of 1966
http://www.kvsun.com/articles/2006/12/11/news/c2bigflood.txt
Southern California flooding history
http://aftf.csusb.edu/documents/AFTF%20Study%20Area%20Flood%20History_ALL.pdf
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