Chad Johnson, Hydrologic Technician
USDA Forest Service
Pacific Southwest Research Station
Fresno, CA
Crjohnson@fs.fed.us
T
he quality of aquatic, riparian, and meadow
ecosystems is directly related to the integrity
of adjacent uplands in their watershed. Forest
Service scientists believe that these ecosystems
are the most altered and impaired habitats of the
Sierra Nevada primarily because of dams and
diversions, overgrazing, roads, logging, and
physical alteration. In 2000 the Kings River
Experimental Watershed (KREW) was
established; it addresses critical issues about the
functioning of Sierra Nevada stream ecosystems
and their response to multiple stresses.
The Kings River Experimental Watershed
Measures Discharge and Sediment Production in Eight
Headwater Streams of the Sierra Nevada, CA
The KREW is located on headwater
tributaries of the Kings River, which
drains into the San Joaquin River
Basin. It is part of the Kings River
Project, Sierra National Forest, which is
a 60,000 ha collaborative study
between research and management.
GOALS
SOME OF THE QUESTIONS TO BE ANSWERED
• Quantify the variability in characteristics of stream
ecosystems and their associated watersheds.
• Evaluate the effects of forest management (prescribed
fire and uneven-aged, small-group tree thinning), while
maintaining older trees, large snags, and large woody
debris throughout the landscape.
• Provide an integrated watershed experiment that
addresses multiple issues such as climate change, air
pollution, and sustainable land management while
providing adequate data for diverse modeling exercises.
• What is the effect of prescribed fire and fuel reduction treatments (i.e., thinning of
trees) on the riparian and stream physical, chemical, and biological conditions?
• Does the use of prescribed fire increase or decrease the rate of
erosion (long term versus short term) and affect soil health and
productivity?
• How is the vegetation affected by treatment, particularly in the
riparian zone? Is riparian vegetation adversely affected by
treatment?
• How do the treatments affect fuel loading?
Carolyn Hunsaker, Research Ecologist
Sean Eagan, Hydrologist
Chris Dolanc, Botanist
Marie Lynch, Hydrologic Technician
Tiffany McClurg, Designer
Funded in part by the National Fire Plan and the
Federal Interagency Joint Fire Science Program
Stream Hydrographs and Precipitation
Events Water Year (WY) 2004
Nested flumes measure discharge of
varying magnitude.
Snow accumulates and melts throughout
the winter at lower elevation sites.
Two flumes are used on each stream to accurately measure both high and low stream discharge. Both rain and
snow events control discharge at the Providence Site, while discharge at the Bull Site is dominated by snow
melt.
Figure 1
California's water needs are met by the snow pack of the Sierra Nevada. Water
collected in the winter and released in the spring allows water agencies to
ensure adequate capacity for the dry summer. In water year 2004 the spring
th
melt began on the 7 of March (Figure 1). Snowmelt typically does not begin
in this region until April. The predicted effects of climate change in the Sierra
Nevada include a shift in timing of snowmelt. This could complicate the water
storage process. KREW's research area spans from the lowest elevations of
snow accumulation (1400 m) to the elevation of maximum accumulation in the
Sierra Nevada (2500 m).
P301
P303
P304
D102
B201
Mineral mass/ area (kg/ha)
Organic mass/ area (kg/ha)
Median particle size (mm)
Peak discharge (l/s)
28
13.3
0.5
108
12
3.4
0.5
91
113.8
24.6
0.125
120
49.3
16
0.25
170
26.5
5
0.25
100
WY 2004
P301
P303
P304
D102
B201
Mineral mass/ area (kg/ha)
Organic mass/ area (kg/ha)
Median particle size (mm)
Peak discharge (l/s)
1.7
0.6
0.5
80
1.4
0.4
0.5
85
6.7
7.5
0.125
43.6
3.8
1.6
0.25
113
1.2
0.5
0.125
21.6
Bulk Mass
(kg/ha)
Peak
Discharge
(l/s)
Largest
Storm
Event
(mm/hr)
Most
Intense
Hour (mm)
WY 2002
WY 2003
WY 2004
Sources of Discharge
METHODS AND DESIGN
3
Annual discharge 1000 m /ha
rain water
(during + 24 hr after)
snow melt
soil water
(1 week-6 months)
base flow
62.3
33.5
33
-
-
118
6.8 for 47
hours
27
69
2.3 for 59
hours
11
Figure 4
Figure 3
Sediment affects the ecology of the stream ecosystem. It can
increase the transport of salts and nutrients, as well as
changing streambed habitat conditions. Figure 3 shows
sediment yield from five different watersheds. While all years
were considered dry, with comparable cumulative
precipitation, the sediment yields differed by two orders of
magnitude. In order to draw conclusions about sediment
production the variability of the watersheds must be
characterized.
Sediment in KREW's streams is sampled to determine
organic content and grain size distribution (Figure 4).
Sediment production in KREW headwaters is sensitive to
th
conditions during storm events. The intense storm on the 7
of November in water year 2003 dropped as much as 27
mm of rain in one hour moving significant quantities of
sediment. Other years had greater percentage of
precipitation falling as snow or as light rain on snow. These
events allowed the water to reach the stream in a slower,
less erosive manner.
uf
f1
P3 8 00
m
04
19
P3
0
0 3 0m
1
P3 92
0 1 5m
19
B2
7
0 3 5m
2
B2 37
0 4 5m
23
75
m
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
1.31 2.55 1.15 1.70 3.77 3.26
0.3
D
Percentage in each category
Data will be gathered for a 4-year reference period and then fire and tree thinning treatments will be applied. After the treatments, data will be gathered for
at least seven years. Each site has a control watershed that receives no treatments, a watershed that is burned, a watershed that is thinned, and a watershed
that is both burned and thinned. We are interested in assessing the integrated condition of the streams and their associated watersheds (i.e., physical,
chemical, and biological characteristics).
• Physical measurements include: upland erosion, stream flow, channel characteristics, suspended sediment, weather conditions, soil characteristics, and
fuel loads.
• Chemical measurements for stream water, shallow soil water, precipitation, and snow melt include: nitrate, ammonium, and phosphate (primary
biological nutrients), chloride, sulfate, calcium, magnesium, potassium, sodium, pH, electrical conductivity, and acid neutralizing capacity.
• Biological measurements include: riparian and upland vegetation, stream invertebrates, and stream algae.
WY 2003
Watershed averages
• How are headwater ecosystems responding to multiple stresses such as climate
change and air pollution?
Meteorology instruments
collect temperature, relative
humidity, solar radiation, wind
speed and direction, snow
depth, precipitation, and snow
water equivalence.
Watershed - Average Elevation
SIGNIFICANCE
• This is the only experimental research site addressing aquatic and watershed questions from
the Sierra Nevada Framework.
• KREW is a demonstration site for both the Joint Fire Science Program and the Forest
Service’s atmospheric deposition effort for critical loads.
• Climate research priorities are addressed: hydrology and nutrient cycling, carbon cycling,
and natural disturbance.
• Effects comparisons will be made to the Fire and Fire Surrogate Study for Sierran-mixedconifer forest at Sequoia National Park.
• Provides information for the Healthy Forests Restoration Act of 2003.
Different sediment sources can also contribute
more or less erosion depending on conditions.
To better understand the dynamics between
upland erosion and in-stream sedimentation,
over 70 sediment fences are placed at hillslope
and road generation sites. Headcuts are being
surveyed so that their annual contributions can
be estimated.
Figure 2
The KREW staff divided discharge water into four categories to better
understand the hydrologic cycle. Rain water is that discharge above base flow
measured during a storm and for the following 24 hours. Snow melt is
discharge above base flow that occurs during the spring melt. Soil water is
defined as water that took one week to six months to reach the stream after it
contacted the soil. Baseflow is the average flow for the month of September historically the driest month on record. The higher elevation sites, B203 and
B204, show a much greater percent of discharge occurring as snow melt. They
also have a greater discharge per area, even though all sites receive similar
amounts of precipitation.
A newly-built sediment pond being filled at a
Bull Creek site.
Sediment accumulated in a sediment fence
after a short summer storm.