The impact of fire on hydrology and suspended sediment and nutrient export in southern California chaparral watersheds Santa Barbara Coastal Long Term

The impact of fire on hydrology and The impact of fire on hydrology and suspended sediment and nutrient suspended sediment and nutrient

export in southern California chaparral export in southern California chaparral watershedswatersheds

The impact of fire on hydrology and The impact of fire on hydrology and suspended sediment and nutrient suspended sediment and nutrient

export in southern California chaparral export in southern California chaparral watershedswatersheds

Santa Barbara Coastal Santa Barbara Coastal Long Term Ecological Research Long Term Ecological Research

(SBC LTER)(SBC LTER)

Santa Barbara Coastal Santa Barbara Coastal Long Term Ecological Research Long Term Ecological Research

(SBC LTER)(SBC LTER)

Masters Research Seminar Masters Research Seminar

ByBy

J. Scott CoombsJ. Scott Coombs

Talk OutlineTalk Outline IntroductionIntroduction

MethodsMethods

HydrologyHydrology

Suspended Sediment ExportSuspended Sediment Export

Nutrient BiogeochemistryNutrient Biogeochemistry

Nutrient Export Nutrient Export

Summary of ResultsSummary of Results

AcknowledgmentsAcknowledgments

QuestionsQuestions

February 23, 2005

Gaviota Wildfire:Gaviota Wildfire: June 5 to 12, June 5 to 12, 20042004

Historical Fires in Study AreaHistorical Fires in Study Area

0 1 2 3 40.5Kilometers

Historical Fires

Los Cruces (1926)

Gaviota (1944)

Refugio (1955)

Homestead (1997)

Gaviota Fire (2004)

Legend

Gaviota

San Onofre

Arroyo Hondo

Streams

Major Roads

±Historical fire perimters, size, and date from CDF FRAP data librariy: http://frap.cdf.ca.gov/data/frapgisdata/select.asp

San Onofre CreekSan Onofre Creek

February19, 2005

Stream SamplingStream Sampling

Stream GaugingStream Gauging

Gaviota Coast Precipitation

0

20

40

60

80

100

120

140

160

1966 1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005

Water Year

Pre

cip

ita

tio

n (

cm

)

Nojoqui Falls Park

Tajiguas Landfill

WY2005 Storm Precipitation Totals

0

10

20

30

40

50

60

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct

Pre

cip

itat

ion

(cm

) Nojoqui Falls Park

Tajiguas Landfill

Changes to Hydrologic Response:Changes to Hydrologic Response:

Infiltration decreasesInfiltration decreases

formation of hydrophobic soil layer formation of hydrophobic soil layer

compaction of soilcompaction of soil

Evapotranspiration and Interception decreaseEvapotranspiration and Interception decrease

more rainfall is available for runoffmore rainfall is available for runoff

Early Season Storm HydrographsEarly Season Storm Hydrographs

October 17 to 29, 2004

0.0

0.2

0.4

0.6

0.8

1.0

1.2

17-Oct-04 20-Oct-04 23-Oct-04 26-Oct-04 29-Oct-04

Dis

char

ge

(cm

hr-1

)

ON02

GV01

HO00

RS02

Mid-Winter Storm HydrographsMid-Winter Storm Hydrographs

February 18 to 24, 2005

0.0

0.5

1.0

1.5

2.0

2.5

18-Feb-05 20-Feb-05 22-Feb-05 24-Feb-05

Dis

ch

arg

e (

cm

hr-1

)

RS02

GV01

HO00

ON02


December 28, 2004

November 15, 2004

October 26, 2004October 19, 2004


February19, 2005

February 22, 2005

April 27, 2005

January 7, 2005 January 26, 2005

Discharge PatternsDischarge Patterns

Cumulative Runoff Rainfall Ratio

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05

Ru

no

ff R

ain

fall

Rat

io

ON02

HO00

RS02

Runoff Rainfall Ratio = Runoff(cm) ÷ Rainfall (cm)

Changes to Sediment Export:Changes to Sediment Export:

Infiltration decreasesInfiltration decreases

Runoff and peak discharge increase Runoff and peak discharge increase

Interception decreases due to vegetation lossInterception decreases due to vegetation loss

Discharge-Suspended Sediment TrendsDischarge-Suspended Sediment Trends

GV01

0

40

80

120

160

200

0 10 20 30 40 50

Discharge (m3 s-1)

Su

sp

en

de

d S

ed

ime

nt

(g L

-1) October 16 to December 10, 2004

December 26 to 29, 2004

December 30, 2004 to May 10, 2005

Pre-Fire (WY2003)

Gaviota WatershedGaviota Watershed

Sediment Deposition in Gaviota: November 22,2004Sediment Deposition in Gaviota: November 22,2004


ON02

0

50

100

150

200

250

300

0 5 10 15 20 25 30

Discharge (m3 s-1)

Su

sp

en

de

d S

ed

ime

nt

(g L

-1) October 19 to December 9, 2004

December 27 to 31,2004January 2 to May 6, 2005

Sediment movement in San Onofre:Sediment movement in San Onofre:

Photos taken May 2005


HO00

0

20

40

60

80

100

120

140

0 5 10 15 20 25 30

Discharge (m3 s-1)

Su

sp

en

de

d S

ed

ime

nt

(g L

-1) October 19 to November 7, 2004

December 27 to December29, 2004

December 30 to December31, 2004

January 2 to May 5, 2005

January 3, 2005 "Flash Flood"

Pre-Fire (WY2003)

Suspended Sediment Storm ExportSuspended Sediment Storm Export

Suspended Sediment Export vs Runoff (cm)

0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35Runoff (cm)

Su

spen

ded

Sed

imen

t E

xpo

rt (

t h

a-1)

ON02 (82% burned)

HO00 (18% burned)

GV01 (7% burned)

MC00 (55% urban)

Late Decmber, 2004 storms

Nitrogen BiogeochemistryNitrogen BiogeochemistryRattlesnake Creek (RS02)

0

150

300

450

600

750

15-Oct-04 12-Nov-04 10-Dec-04 07-Jan-05 04-Feb-05 04-Mar-05 01-Apr-05 29-Apr-05 27-May-05

Co

nce

ntr

atio

n (

μM

)

0.0

0.5

1.0

1.5

2.0

2.5

Dis

char

ge

(m3 s

-1)

DON

Nitrate

Ammonium

RS02 Discharge

San Onofre (ON02)

0

150

300

450

600

750

15-Oct-04 12-Nov-04 10-Dec-04 07-Jan-05 04-Feb-05 04-Mar-05 01-Apr-05 29-Apr-05 27-May-05

Co

nce

ntr

atio

n (

μM

)

0.0

0.5

1.0

1.5

2.0

2.5

Dis

char

ge

(m3 s

-1)

DON

Nitrate

Ammonium

ON02 Discharge

Nitrogen BiogeochemistryNitrogen Biogeochemistry

Dissolved Nitrogen ResponseDissolved Nitrogen Response

ON02

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%


Per

cen

t o

f T

ota

l N

itro

gen

Sto

rm E

xpo

rt

DON

Nitrate

Ammonium

RS02

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%


Per

cen

t o

f T

ota

l N

itro

gen

Sto

rm E

xpo

rt

DON

Nitrate

Ammonium

Nitrate Storm ExportNitrate Storm Export

Nitrate Export vs Runoff (cm)

0

100

200

300

400

500

600

700

800

900

0 5 10 15 20 25 30 35

Runoff (cm)

Nit

rate

(m

ole

s h

a-1)

ON02 (82% burned)

RS02 (unburned)

MC00 (55% urban)

BC02 (24% agriculture)

DON Storm ExportDON Storm Export

Dissolved Organic Nitrogen vs Runoff (cm)

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35

Runoff (cm)

DO

N (

mo

les

ha-1

)

ON02 (82%)

RS02 (unburned)

MC00 (55% urban)


October 19-20, 2004

October 26-27, 2004

Changes in Phosphate ExportChanges in Phosphate Export

Phosphate is rapidly mineralized and deposited on soil Phosphate is rapidly mineralized and deposited on soil surface but is not as mobile as nitratesurface but is not as mobile as nitrate

Increases in phosphate concentration in runoff roughly Increases in phosphate concentration in runoff roughly correlates with peak dischargecorrelates with peak discharge

Phosphate Storm ExportPhosphate Storm Export

Phosphate Export vs Runoff (cm)

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35

Runoff (cm)

Ph

osp

hat

e (m

ole

s h

a-1)

ON02 (82% burned)

GV01 (7% burned)

RS02 (unburned)

MC00 (55% urban)


Summary of ResultsSummary of ResultsHydrologyHydrology Hydrologic response was typical for southern California Hydrologic response was typical for southern California

chaparral during early season storms but differences chaparral during early season storms but differences decreased as the season progressed with above decreased as the season progressed with above average rainfall.average rainfall.

Suspended SedimentSuspended Sediment 10-fold increase in suspended sediment export10-fold increase in suspended sediment export

NutrientsNutrients 30 times increase in ammonium export30 times increase in ammonium export 5.5 times increase in nitrate export5.5 times increase in nitrate export 2.8 times increase in DON export2.8 times increase in DON export 2 times increase in phosphate export2 times increase in phosphate export

AcknowledgementsAcknowledgementsSpecial thanks toSpecial thanks to My advisors: John Melack, Arturo Keller, and Jordan Clark.My advisors: John Melack, Arturo Keller, and Jordan Clark. Frank Setaro and Allen Doyle for their assistance in sample Frank Setaro and Allen Doyle for their assistance in sample

processing and analysis.processing and analysis. Tim Robinson and Al Leydecker for their advice and solace.Tim Robinson and Al Leydecker for their advice and solace. My family and friends for their support and encouragement.My family and friends for their support and encouragement.

My wife, Maria, for her love and understanding of my My wife, Maria, for her love and understanding of my absence on all those rainy nights.absence on all those rainy nights.

Questions?Questions?

Documents

The impact of fire on hydrology and suspended sediment and nutrient export in southern California chaparral watersheds Santa Barbara Coastal Long Term