Transcript Document

Nutrient Export Coefficient Modeling in
Mediterranean Coastal Streams
Timothy H. Robinson, Al Leydecker, Arturo A. Keller and John M. Melack
Bren School of Environmental Science & Management
University of California, Santa Barbara, USA
Santa Barbara Coastal
LTER - NSF
UC Marine Council
Study
Area
Watershed Characteristics
SF
LA
Watersheds
Drainage Area Max-Elevation Ave-Slope
2
Carpinteria
Franklin
Santa Monica
(km )
39.2
11.6
9.8
(m)
1424
533
1192
(ft)
4672
1749
3911
(%)
38
20
45
Urban
Agriculture
Chaparral/Forest
(%)
2
29
3
(%)
11
30
3
(%)
85
40
93
Specifics:
Analyzing for:
Ammonium (NH4+), Nitrate (NO3-), Total Dissolve
Nitrogen (TDN), Phosphate (PO43-), Total Particulate
Carbon (TPC), Total Particulate Nitrogen (TPN), Total
Particulate Phosphate (TPP), Total Suspended
Sediments (TSS) and major ions at selected locations
Frequency:
• Regular sampling:
Once every 2 weeks during the dry season
Once a week during the wet season
• Storm sampling:
Every hour on the rising limb of the hydrograph
Every 2-4 hours on the falling limb of the hydrograph
Project duration: WY2001, WY2002 and WY2003
Annual Basin Nutrient Export
Water Year 2001 and 2002
10
2001
2002
20
15
10
5
Nitrate Export (kg-N ha-1yr-1)
Annual Discharge (cm yr -1)
25
0
Franklin
Carpinteria
8
6
4
2
0
Santa Monica
Franklin
8
Carpinteria
Santa Monica
1.5
2001
2002
6
4
2
Phosphate Export (kg-P ha -1yr-1)
PON Export (kg-N ha-1yr-1)
2001
2002
2001
2002
1.0
0.5
0.0
0
Franklin
Carpinteria
Santa Monica
Franklin
Carpinteria
Santa Monica
Nutrient Export Coefficient Model
(NEC-M)
L   Ei A I K  D
i
L
A
E
GIS
I
i
i
I
K
Datm
Interview Literature Literature
E  b (LU )
LU
GIS
atm
Literature
K  keat
b
k
t
a
d/v
S+P
Abbreviation key:
• L – Nutrient Export (loss) (mass area-1 time-1)
• E – Export Coefficient Function
• b – Watershed Response Variable
• LU – Land use
• S – Soils
LTER
Datm
•
•
•
•
•
P – Precipitation
A – Land Use Area
I – Nutrient input rate
K – Down Stream Distance-Decay Function
k and a – Coefficients
• t – Time
• d – Distance Traveled Downstream
• v – Average Velocity Traveled
Downstream
• Datm – Atmospheric deposition
Spatial Extent of Land Use Class (A)
WY2001
WY2002
WY2003
Land Use:
•Chaparral/Forest
•Avocado
•Greenhouse
•Nursery
•Residential
•Commercial
#
1
1
1
2
3
4
5
6
6
Land Use
Area
% Target
% Secondary
% Impervious
Class
(hectares)
Land Use
Land Use
Surface
Chaparral/Forest
1873
100
0
0
Chaparral/Forest
1210
100
0
0
Chaparral/Forest
902
100
0
0
Avocado
747
36
42 (Chap/For)
7
Greenhouse
17
97
3 (Chap/For)
68
Nursery
80
47
21 (Avo) / 12 (Chap/For)
11
Residential
6
100
0
30
Commercial
32
91
9 (Chap/For)
77
Nutrient Export
WY2002
1.4
0.40
Chaparral/Forest
0.35
0.30
0.25
NH4
0.8
NO3
0.20
PO4
0.6
flow
0.4
0.15
0.10
0.2
0.05
0.0
0.00
9/16
12/25
4/4
7/13
10/21
3 -1
1.0
Flow (m s )
Cumulative Export (kmols)
1.2
 Hourly time-step
 Hydrology:
• Pressure Transducer
• Observed stage
• HEC-RAS
 Stream Chemistry
 Modeling
Nutrient Export Coefficient (E)
2500
50
baseflow
baseflow
1500
1000
500
E  LUb
stormflow
30
20
10
0
0
Franklin
b
Carpinteria
Santa Monica
Franklin
10000
WY 2001
Santa Monica
8
7
flow
1000
6
TDN
5
NO3
(kmol)
E – Export Coefficient Function
b – Watershed Response Variable
S – Soils
P – Precipitation
Carpinteria
Franklin Creek
S+P
cumulative export
LU
GIS
40
100
4
3
PO4
10
2
NH
4
1
1
5-Jan
0
15-Jan
25-Jan
4-Feb
14-Feb
24-Feb
6-Mar
discharge (m3 s-1)
E
stormflow
phosphate (SRP, µM)
nitrate (µM)
2000
Scaling the Export Coefficient (b)
• Storm to Storm relationships.
• Volume Weighted Mean Concentrations vs. Cumulative
Rainfall.
• Volume Weighted Mean Concentrations vs. Rainfall/Runoff
Ratio.
• Topographic Index (TI): variable source area.
• Antecedent Soil Moisture Content: SSURGO soils data,
texture->porosity, infiltration rates, evapotranspiration rates,
depth to impervious layer, etc.
Nutrient Flux (normalized by runoff)
10000
-1
-1
NO3 Export (g ha mm )
NO3-Commercial
1000
WY2002
NO3-Residential
NO3-Greenhouse
NO3-Chaparral/Forest
100
10
1
0.1
0.01
10/30 11/12
11/24 11/29
12/2
12/14 12/20
12/30
1/27
2/17
3/7
5/20
VWM vs. Runoff/Rainfall
1500
VWM Concentration (µM)
Greenhouse
y = 227.45Ln(x) + 1046.6
R 2 = 0.52
1000
NO3
PO4
500
y = -91.22Ln(x) + 114.48
R 2 = 0.71
0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Runoff/Rainfall Ratio
0.7
0.8
0.9
1.0
Conclusions
• High frequency storm sampling is critical.
• Nutrient Export Coefficients in Mediterranean climates must
be a function that is related to the watershed runoff response
and not a single annual term.
• Analysis of the final year of data will solidify scaling
techniques in NEC-M.
• Future work: implement the model in the study watersheds
and test its portability in a catchment outside of the area
(e.g. Spain).
Questions
Thank you !
Nutrient Watershed Flux
12,000
Nutrient Loading (kg/yr)
NH4-N
10,000
NO3-N
DON-N
8,000
PO4-P
6,000
4,000
2,000
0
Santa Monica
Franklin
Carpinteria
Climatic Regime
250
Downtown Santa Barbara, 30 m
San Marcos Pass, 671 m
150
100
50
0
1965
25
1970
1975
1980
1985
1990
Downtown Santa Barbara, 30 m
San Marcos Pass, 671 m
20
15
10
5
l
ug
A
Ju
Ju
n
M
ay
pr
A
M
ar
Fe
b
n
Ja
ec
0
D
1960
Se
pt
O
ct
N
ov
1955
Avg Monthly Precipitation, cm
Annual Rainfall, cm
200
1995
2000
Sampling Site Locations
Land Use:
•Chaparral/Forest
•Avocado
•Greenhouse
•Nursery
•Residential
•Commercial
WY2001
WY2002
WY2003
Linkage – Stream Network & Chemistry
Arc Hydro Geodatabase: geometric network
representation of the connectivity of surface
water
• HydroNetwork
DEM analysis
• HydroEdge
• HydroJunctions
• SchematicLinks+Nodes
• HydroPointEvent
• HydroLineEvent
Drainage Network + Sampling Points
Visual Basic for Application:
MS Excel/Access:
Location
Carpinteria @ Calle Ocho
Carpinteria @ Vedder's
Carpinteria @ 6 St. manhole
Carpinteria @ Casitas Village drain
Franklin @ Carpinteria Ave
Franklin @ Meadow View ramp
Franklin @ Meadow View drain
Franklin @ Girls Club on Foothill
ID
CP00
CP05
CP20
CP30
FK00
FK03
FK04
FK06
LTER #
30001
30002
30003
30004
30005
30006
30007
30008
date
3-Oct-02
3-Oct-02
3-Oct-02
3-Oct-02
3-Oct-02
3-Oct-02
3-Oct-02
3-Oct-02
time
18:50
12:20
19:10
18:40
20:05
19:50
19:55
19:40
NH4
uM
2.8
0.5
1.7
114.0
5.2
0.7
5.3
1.0
NO3
uM
257.8
26.3
139.3
0.7
1712.9
2227.2
666.7
2180.7
PO4
uM
1.9
3.4
3.6
187.5
6.0
2.9
125.5
1.1
Measuring Stream Flow
Staff Gauges and Pressure Transducers
Surveying the Cross-Sections
Developing Rating Curves
Nutrient Loading
Development of a Nutrient Flux Model
Stream
Chemistry
Stream
Chemistry
PT
Stage
(5-min)
Observed
Stage
Observed
Flow
Stream
Chemistry
(hourly)
Identify:
Baseflow, Peakflow..
Nut. Conc.
Stage-Discharge Relationship
(HEC-RAS)
Observed
Flow
(hourly)
Flow
(hourly)
Stream
Chemistry
(model/obs)
Flow
(hourly)
PT
Flow
(5-min)
Flow
(hourly)
Linear extrapolation
Nut. Flux
(conc/flow)
Annual
Nutrient Loading
Precipitation WY2002
Cumulative
Storm
Storm Rainfall Rainfall Duration
(date)
(mm)
(hours)
10/30
10.2
7
11/12
45.7*
38
11/24
40.6
4
11/29
10.2
10
12/2
7.6
5
12/14
5.1
3
12/20
10.2
6
12/30
22.9*
34
1/27
12.7
5
2/17
10.2
15
3/7
5.1
6
5/20
5.1
2
* Two short pulses during the time period.
Nutrient Flux (normalized by runoff)
PO4-Commercial
WY2002
-1
PO4 Export (g ha mm )
1000
PO4-Residential
PO4-Greenhouse
100
-1
PO4-Chaparral/Forest
10
1
0.1
10/30 11/12
11/24
11/29
12/2
12/14
12/20
12/30
1/27
2/17
3/7
5/20
Attenuation (K)
•
•
•
•
K
Literature
at
K  ke
k
t
D/V
a
Distance from stream
Distance from basin outlet
Type of riparian corridor
Dispersal Area and Trapping
Likelihood (BI Index)
VWM vs. Cumulative Rainfall
VWM - Volume Weighted Mean
1500
VWM Concentration (µM)
Greenhouse
NO3
PO4
Trendline for NO3
y = 3.9245x + 463.75
1000
2
R = 0.42
500
0
0
20
40
60
80
100
120
140
Cumulative Rainfall (mm)
160
180
200
VWM vs. Cumulative Rainfall
VWM - Volume Weighted Mean
100
1500
NO3
PO4
80
VWM Concentration (µM)
VWM Concentration (µM)
Residential
2
R = 0.38
60
40
20
0
1000
500
0
0
20
40
60
80
100
120
140
Cumulative Rainfall (mm)
160
180
200
VWM vs. Runoff/Rainfall
15
VWM Concentration (µM)
Chaparral/Forest
NO3
PO4
10
y = 0.1293x -0.7348
R 2 = 0.5155
5
0
0.00
0.01
0.02
0.03
0.04
0.05
Runoff/Rainfall Ratio
0.06
0.07
0.08