influence of catchment characteristics on stream nitrogen transport to the hood canal
DESCRIPTION
Influence of Catchment Characteristics on Stream Nitrogen Transport to the Hood Canal. Osborne, S.N.; Brett , M.T.; Richey, J.E.; Steinberg, P.D.; Newton, J. A.; and Hannafious, D. Hood Canal Dissolved Oxygen Program University of Washington. Outline. General Watershed Characteristics - PowerPoint PPT PresentationTRANSCRIPT
Influence of Catchment Characteristics on Stream Nitrogen Transport to the Hood Canal
Osborne, S.N.; Brett , M.T.; Richey, J.E.;
Steinberg, P.D.; Newton, J. A.; and Hannafious, D.
Hood Canal Dissolved Oxygen ProgramUniversity of Washington
Outline• General Watershed
Characteristics-Hydrology-Land Cover
• Study Objectives-Estimate freshwater N loads (possible cause of Hood Canal hypoxia)
• Results-Seasonal variation in N loads/concentrations-Land cover effects on load/concentrations-Discharge effects on load/concentrations
• Drainage Basin Area– Hood Canal
Watershed (2119 km2)– Individual Catchments
(35)• (0.05 to 628 km2)
• Slope – Individual Catchments
• (2.6 to 30.3 degrees)
Watershed Characteristics
Surface Water Contribution from Hood Canal Streams
Skokomish ~ 35.7%
Dosewallips ~ 11.4%
Lake Cushman ~ *10%
Hamma Hamma ~ 10%
Duckabush ~ 8.1%
Big Quilcene ~ 7.7%
Tahuya ~ 3.6%
All Other Sites ~ 23.9%
Annual Precipitation
0
30
60
90JA
N
FE
B
MA
R
AP
R
MA
Y
JUN
JUL
AU
G
SE
P
OC
T
NO
V
DE
C
Pre
cip
itatio
n (m
m)
2005
1990-2004 Avg
Surface Water Hydrology
0
200
400
600
800
JAN
FEB
MAR AP
R
MAY JU
N
JUL
AUG
SEP
OCT
NOV
DEC
Disc
harg
e (m
3/s
)
2005
1990-2004 Average
Land Cover• 14 Categories
• Dominant LC Types
Hood Canal Watershed:– Mature Conifer
(48.2%)
– Deciduous/Mixed(10.9%)
– Young Conifer(8.3%)
– Sub-Alpine Forest
(5.5%)
Watershed Characteristics
• Estimate total freshwater nitrogen loading to Hood Canal
• Identify seasonal trends in surface water nutrient concentrations and loading
• Examine the effect of catchment characteristics on nutrient transport (i.e. land cover, soil type, drainage basin area, slope, and discharge)
• Compile a dataset that can be used to develop and calibrate a watershed biogeochemical model
Study Objectives
1) Analytes (Monthly Sampling and Storm Event Sampling): • Dissolved Nutrients (ORP, NO3-N, NO2-N, NH4-N, and SiO4-
Si) • Dissolved Organic Carbon & Total Dissolved Nitrogen• Particulate Organic Carbon & Total Particulate Nitrogen• Total Phosphorus• Total Suspended Solids
2) Data Management & QA/QC
3) GIS Analysis• Watershed and Individual Catchment Characteristics
» Land Cover, Soil Type, Drainage Basin Area, Slope
4) Field Discharge Measurements and Hydrologic Modeling
5) Statistical Analysis of Data
Methods
HCDOPMonthly Sampling
Program
• 38 Sampling Locations
• ~80% of surface water discharge to Hood Canal
ResultsNitrogen Load from Hood Canal Streams
• 2005: 935 metric tons TN (Dry year)Total Dissolved Nitrogen (760 mt/yr) Particulate Nitrogen (175 mt/yr)
(DIN ~ 75% of TDN = 570 metric tons)
TDN Composition
Nitrate-N (68±19%) DON (24±16%)
Ammonium-N (7±11%) Nitrite-N (0.3±0.2%)
• 1990-2004 Averages Discharges with 2005 Nutrient Data1250200 metric tons TN
(750 130 metric tons DIN)
• USGS Preliminary Assessment/Prediction 421 ± 162 metric tons (DIN)
2005 Nitrogen Loading and Speciation Hood Canal Streams
0
200
400
600
800T
HO
RT
AR
BL
QU
IB
QU
I D
OS
ED
UC
KF
UL
TW
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MJO
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EA
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LA
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CL
ILL
MIL
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INC
HIL
LS
KO
KU
NIS
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EN
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DE
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NA
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AN
TW
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PP
HO
LY
DE
VE
UN
IOM
ISS
LIM
IS
TIM
TA
HU
DE
WA
BA
ND
ST
AV
SE
AB
BB
EE
West South North East
Tot
al A
nn
ual
Loa
d (
met
ric
ton
s)
NO3-N DON PN NH4-N NO2-N
2005 Nitrogen Concentrations and Speciation for Hood Canal Streams
0
400
800
1200T
HO
RT
AR
BL
QU
IB
QU
I D
OS
ED
UC
KF
UL
TW
AK
EH
AM
MJO
RS
EA
GL
LA
KE
CL
ILL
MIL
LF
INC
HIL
LS
KO
KU
NIS
TR
AI
BB
EN
AL
DE
UN
NA
TW
AN
TW
AF
MU
LB
HA
PP
HO
LY
DE
VE
UN
IOM
ISS
LIM
IS
TIM
TA
HU
DE
WA
BA
ND
ST
AV
SE
AB
BB
EE
West South North East
Flo
w W
eigh
ted
TN
Con
cen
trat
ion
(m g
/L) NO3-N DON PN NH4-N NO2-N
Seasonality of Nitrogen Loads and Concentrations
– Peaks of loading and flow-weighted concentrations occur during rainy months
– Dry January/February 2005 resulted in lower loading and concentrations
– Nitrate is dominant fraction of TDN during months of low biological uptake (winter & fall), DON is dominant fraction of TDN during months of high biological uptake (summer).
2005 Seasonal Cycle of Nitrogen Transport and Speciation in Hood
Canal Streams
0
100
200
300
Flo
w W
eig
hte
d C
on
cen
tra
tion
(m g
/L) NO3-N DON PN NH4-N NO2-N
NO2-N 1 1 1 0 0 0 0 0 1 1 1 1
NH4-N 13 11 11 11 7 8 18 9 19 16 17 16
PN 21 6 13 16 18 20 7 1 2 5 20 49
DON 30 14 57 75 46 57 43 34 48 29 24 57
NO3-N 76 75 88 47 36 28 43 43 48 63 110 118
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
WINTER SPRING SUMMER FALL
Seasonal Cycle of Nitrogen Loads from Rivers/Streams to Hood Canal (2005)
0
50
100
150
200
250
300JA
N
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JU
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TN
Lo
ad
(m
etr
ic t
on
s/m
o) NO3-N DON PN NH4-N NO2-N
Loading Rates of Hood Canal Streams are Discharge Dominated
0
200
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800JA
N
FEB
MAR AP
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MAY JU
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DEC
Disc
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e (m
3/s
) 2005
1990-2004Average
Land Cover Effects on TDN Concentrations
y = 0.01x + 0.12
R2 = 0.39
0.0
0.5
1.0
0 20 40 60 80
% Deciduous Mixed Forest
Aver
age
TDN
Conc
entr
atio
n (m
g/L)
y = -0.01x + 0.49
R2 = 0.26
0.0
0.5
1.0
0 20 40 60 80 100
% Mature Coniferous Forest
-Deciduous Mixed Forest Cover Type: Red alder (Alnus rubra), a nitrogen fixer, is a major species.
-Low to medium density residential areas (with septic systems) are included Deciduous Mixed Forest type at this resolution
Influence of Deciduous/Mixed & Mature Conifer Forests on Nutrient
Concentrations• Nutrient Rich: TDN > 600 mg/L• Nutrient Poor: TDN < 150 mg/L
% DMF
% MCF Sites Identified
Nutrient Rich Streams (n=4)
30 18 Tarboo, Seabeck, Devereaux, Little Quilcene
Nutrient Poor Streams (n=11)
7 57 Dosewallips, Duckabush, Big Quilcene, Fulton, Waketickeh, Jorsted, Miller, Skokomish R.,
Unnamed Drainage, and Twanoh
Deciduous Mixed Forest
Mature Conifer Forest
Rainwater reference
Rainwater reference
• 8 of the 12 streams identified as nutrient poor are located on the west shore of Hood Canal.
West shore streams have:• Larger average watershed areas (49.4 km2 vs. 5.7
km2),• Headwaters in Olympic National Park• Higher average discharges (1.9 vs. 0.3 m3/s)• Greater average slopes (19.9 vs. 6.5 degrees)• Lower average nitrogen concentrations and
greater loads
Other Characteristics of Nutrient Poor Streams
- Sample streams every 2 – 4 hours during 2 – 4 day storm events
- Estimate discharge effects on nutrient concentrations
- Refine N loading estimates
Next Step: Estimating Storm Event Effects on Nutrient Concentrations
100%
100% ~800%
100% ~800%
~150%
100% ~800%
~150% <50%
1) Land cover (vegetation and land use) influences stream nutrient transport.
-Catchments dominated by Mature Conifer Forest retained nitrogen more efficiently.
-Catchments dominated by Mixed Deciduous Forest had higher nitrogen concentrations.
-Catchments dominated by Open Forest Regrowth had higher particulate nitrogen concentrations.
Conclusions
2) Larger rivers with headwaters in Olympic National Park (predominantly mature conifer forest) were typically associated lower N concentrations, but larger N loads
3) In stream nitrogen concentrations were generally low (<1 mg/L) and nitrate was the dominant fraction of TDN.
4) Stream nitrogen concentrations patterns are strongly seasonal.
5) Total surface freshwater N load is higher than initial estimates.
Conclusions cont.