Timothy H. Robinson John M. Melack Arturo A. Keller
description
Transcript of Timothy H. Robinson John M. Melack Arturo A. Keller
Nutrient Concentrations in Coastal Streams, Variation with Land Use in the
Carpinteria Valley (Santa Barbara Coastal LTER)
Timothy H. RobinsonJohn M. MelackArturo A. Keller
Bren School of Environmental Science and ManagementUniversity of California Santa Barbara
Outline of the talk
Project overview
Sampling strategy and location
Measuring stream nutrient concentrations and flow
Nutrient loading and the development of a flux model
Basin outlet mass flux
Comparison of nutrient loading by land use type
Nutrient export coefficient modeling
Integration with an urban growth model
Project Overview
Watersheds Drainage Area Max-Elevation Ave-Slope Urban Agriculture Chaparral/Forest(km2) (m) (ft) (%) (%) (%) (%)
Carpinteria 39.2 1424 4672 38 2 11 85Franklin 11.6 533 1749 20 29 30 40
Santa Monica 9.8 1192 3911 45 3 3 93
Methodology
Identify land use classes and sampling site locations: Chaparral/Forest, Avocado, Greenhouse, Open-Field Nursery, Residential and Commercial
Sampling strategies: Subcatchment, point discharge and above-below
Sampling methods: Manual sample or ISCO auto-sampler
GIS database development
Data analysis
Nutrient flux calculation (hydrology and stream chemistry)
Nutrient export coefficient model development
Integration with an urban growth model
Sampling Site Locations
Measuring Nutrient Concentrations
Grab samples and ISCO auto- samplers
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 a week during the wet seasonOnce every 2 weeks during the dry season
• Storm sampling:Every hour on the rising limb of the hydrographEvery 2-4 hours on the falling limb of the hydrograph
Specifics:
Measuring Stream Flow
Staff Gauges and Pressure TransducersSurveying the Cross-Sections
Developing Rating Curves
Stream Chemistry and Hydrology
0
300
600
900
1200
10/30 10/31 11/1
Nitr
ate
(µM
)
0.6
0.8
1.0
1.2
1.4
Stag
e at
out
let (
ft)
outlet
commercial
residential
chaparral/forest
stage-recorded
Carpinteria Creek (WY-2002)
General Trends in Nutrient Concentrationsby Watershed
1
10
100
1000
10000
Franklin Carpinteria Santa Monica
nitr
ate
(µM
)
baseflow
stormflow
1
10
100
Franklin Carpinteria Santa Monica
phos
phat
e (µ
M)
baseflowstormflow
Nutrient LoadingDevelopment of a Nutrient Flux Model
StreamChemistry
ObservedStage
PTStage
(5-min)
ObservedFlow
PTFlow
(5-min)Stream
Chemistry
Stage-Discharge Relationship(HEC-RAS)
Flow(hourly)Flow
(hourly)
StreamChemistry(hourly)
Identify: Baseflow, Peakflow..
Nut. Conc.Flow
(hourly)
StreamChemistry
(model/obs)
Nut. Flux(conc/flow)
AnnualAnnualNutrient LoadingNutrient Loading
ObservedFlow
(hourly)
Linear extrapolation
0
20
40
60
80
100
120
140
160
10/28 11/7 11/17 11/27 12/7 12/17
Conc
entr
atio
ns (u
M)
0
0.5
1
1.5
2
2.5
3
3.5
4
Flow
(cfs
)
Model-NO3Series2FlowNO3 observedNO3 modeled
Modeled vs. Observed
Residential - CP30
Cumulative Nitrate ExportNursery Site
0
20
40
60
80
100
120
140
160
180
10/26 11/5 11/15 11/25 12/5 12/15 12/25
Cum
ulat
ive
Expo
rt (K
mol
)
0
20
40
60
80
100
120
Flow
(cfs
)
NO3-FK07NO3-FK06Flow-FK07Flow-FK06
1
10
100
1000
10000
5-Jan 15-Jan 25-Jan 4-Feb 14-Feb 24-Feb 6-Mar
cum
ulat
ive
expo
rt(K
mol
)
0
50
100
150
200
250
flow
(cfs
)
NH4 NO3 PO4
TDN flow
WY 2001
Basin Nutrient Export Franklin Creek Watershed
0
2,000
4,000
6,000
8,000
10,000
12,000
Santa Monica Franklin Carpinteria
Nutri
ent L
oadi
ng (k
g/yr
)
NH4-N
NO3-N
DON-N
PO4-P
WY2001 Basin Outlet Mass Flux
WY 2001
Comparison of Flux afterNormalizing with Runoff
1
10
100
Oct. 30 Nov. 29 Dec. 20Date of Storms
Expo
rt (g
/ha-
mm
)
NO3-residentialNO3-commercialNO3-greenhouse
0
1
10
100
1000
Oct. 30 Nov. 29 Dec. 20Date of Storms
Expo
rt (g
/ha-
mm
)
PO4-residentialPO4-commercialPO4-greenhouse
AAGISGISEE
IIInterviewInterview
IILiteratureLiterature
KKLiteratureLiterature
LUE tkeK
kk ttD/VD/V
LULUGISGIS
Abbreviation key:• E – Export Coefficient Function• B – Watershed Response Variable• S – Soils• P - Precipitation
Nutrient Export Coefficient Model
DKIAEL atmiiii
DDatmatmLTERLTER
DDatmatmLiteratureLiterature
S+P +ASMCS+P +ASMC
• ASMC – Antecedent Soil Moisture Content• K – Down Stream Distance-Decay Function• k + – Coefficients• t – Time
• D – Distance Traveled Downstream• V – Average Velocity Traveled Downstream
L
Integration with an Urban Growth Model (SLEUTH)
• SLEUTH : an urban growth model implemented for the Santa Barbara area that predicts future land use, example 2050
• Enables comparison of future loadings to standards being set for stream water quality regulations (TMDLs)
• Evaluation of proposed BMP mitigations
Conclusions• Stream nutrient concentrations only partially tell the story
• Hydrology is the critical element of any flux calculation, which is necessary to characterize nutrient loading
• The finer the sampling strategy the better the results, particularly with urban/agriculturally dominated sites
• Creating a dedicated and enthusiastic group of stream samplers is a crucial component of any project of this nature
• Nutrient export coefficients for a Mediterranean climate need to accommodate the high inter/intra-year storm variability
• A minimum of two years of data are needed to statistically validate model results
• Hope for rain!!
Questions
Thank you