Investigating the Linkage between Water Quality and Water Quantity in Watershed Management Richard L. Kiesling 1 United States Geological Survey, Water Resource Division, Texas District, 8027 Exchange Drive, Austin, TX, 78754 2 Environmental Science Institute, University of Texas, Austin, TX, 78712
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Investigating the Linkage between Water Quality and Water Quantity in Watershed Management Richard L. Kiesling 1 United States Geological Survey, Water.
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Investigating the Linkage between Water
Quality and Water Quantity in
Watershed Management
Richard L. Kiesling 1United States Geological Survey, Water Resource Division, Texas District, 8027 Exchange Drive, Austin, TX, 78754
2Environmental Science Institute, University of Texas, Austin, TX, 78712
Why Evaluate Impact of Streamflow?
• Streamflow acts as a master variable• Controls Water Residence Time• Regulates Rates of Physical Disturbance • Regulates Nutrient and Carbon Cycling
– nutrient uptake length a function of stream depth and velocity (e.g., Valett et al. 1996)
– nutrient assimilation and turnover rates a function of discharge (Butterini and Sabater 1998).
Headw ater inputs f rom Upper Rio GrandeOriginal Flow f rom WLE 60% of Median Flow * 40% of Median Flow *
Rio Grande: Alternative Load Scenarios
QUAL-TX Predicted Dissolved Oxygen ConcentrationsSegment 2308: Rio Grande Be low International Dam
4
5
6
7
8
012345678910111213141516171819202122232425262728
Original QUAL-TX WLE 7Q2 flow (0.245 m3/s, BOD=20mg/L))
60% of Fort Quitman Median Flow (3.6 m3/s, BOD=20 mg/L)
40% of Fort Quitman Median Flow (2.4 m3/s, BOD=20 mg/L)
Rio Grande: Alternative Load Scenarios
QUAL-TX Predicted Dissolved Oxygen ConcentrationsSegment 2308: Rio Grande Below International Dam
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5
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7
8
012345678910111213141516171819202122232425262728
60% of Fort Quitman Median Flow (3.6 m3/s, BOD=20 mg/L)40% of Fort Quitman Median Flow (2.4 m3/s, BOD=20 mg/L)Additional BOD Load Scenario 1 (Flow=3.6 m3/s, BOD=40)Additional BOD Load Scenario 2 (Flow=2.4 m3/s, BOD=40)
Rio Grande: Alternative Load Scenarios
Water Quality Simulations: North Bosque
• Used Calibrated TNRCC QUAL-TX Model
• Modified Headwater Flow– Default Instream Flow restriction based on 60% or 40%
of median daily flow recorded at Clifton Gage
• Conserved Pollutant Load
• Modeled Alternative Load Scenarios– Increased BOD load by 20mg/L for two flow scenarios
• Potential exists for economic trade-off between wastewater treatment costs and instream flow to maintain assimilative capacity
• Integrated water resource management requires the simultaneous assessment of streamflow manipulation and assimilative capacity– Does this apply to all constiuents?
System Model of Nutrients and Watershed Eutrophication
• Nutrient supply can limit algal production• Nutrient enrichment from watershed and marine
sources can control extent of limitation• Control Points within watersheds dictate trophic-
level responses to nutrient enrichment; for example– Frequency and magnitude of loads– Spatial and temporal change in LULC– Hydro modification (entrenchment, diking)
In-stream Methods: algal production
• NDS periphytometers apparatus design –– Liquid media diffusing through two-layer substrate
• 0.45 micron nylon barrier filter• GFF substrate - analyzed for algal biomass or carbon
• Factorial Experiments – factors, 1 level each, interaction term– Six Sites in North Bosque River Watershed– Nutrient media additions of 350 uM N and 100 uM P– Eight replicates per treatments– 10-14 day deployments; micro and macro methods
TIAER Graphic; used by permission
BO070
BO090
NC060
BO060
BO040
Matlock Periphytometer, North Bosque River, Hico TX
Micro-NDS Periphytometer, North Bosque River, Hico TX
North Bosque Control Periphyton Productivity
0
100
200
300
400
500
Site
Pro
du
ctiv
ity
(μg
Ch
la/m
2 /day
)
0
10
20
30
40
50
Pro
du
ctiv
ity
(mg
DW
/m2/d
ay)
May 2001 Aug 2001 Oct 2001 Jan 2002 Apr 2002
USGS 08095000 North Bosque nr Clifton
0
500
1000
1500
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Mo
nth
ly-M
ea
n D
isc
ha
rge
(c
fs)
2000
2001
2002
North Bosque Ambient Chemistry 2001-2002
0
0.5
1
1.5
2
2.5
BO020 BO040 BO060 BO070 BO090 NC060
Ph
osp
ho
rus
(mg
/L)
0
50
100
150
200
250
Per
iph
yto
n P
rod
uct
ion
(μg
Ch
la /m
2/d
ay)
Average of PO4-P (mg/L) Average of TP (mg/L)
Periphyton Production
Bosque River, TX, P-Limited Production
0.0
0.4
0.8
1.2
0.0 0.4 0.8 1.2 1.6 2.0
Instream SRP (mg/L)
Ind
ex
of
Re
lati
ve
Pro
du
cti
on
(L
ET
SI)
1997-98 2001-2002 Monod Model
Monod Model:umax =0.98; Ks =0.01
R2 = 0.73; p < 0.05
North Bosque Monthly-Mean NPP: 2001-2002
0
1
1
2
2
May June July August
Month
Net
Pri
mar
y P
rod
uct
ion
(m
g O
2/L
/hr)
BO040
BO060
BO070
BO090
USGS 08095000 North Bosque nr Clifton:Monthly-Mean Discharge
0
50
100
150
200
May June July August
Month
Dis
char
ge (c
fs)
2001 Q
2001-2002 Mean Q
2001-2003 Mean Q
Conclusions: Watershed Eutrophication
• Nutrient-limited periphyton primary production conforms to resource-consumer model of population growth based on resource supply rate
• Periphyton primary productivity is elevated along the instream nutrient concentration gradient, documenting a change in trophic status
• Periphyton and water-column primary productivity at Clifton (BO090) track mean discharge as well as nutrient concentration
Micro-NDS PeriphytometerTaos Ski Valley, New Mexico
Micro-NDS Periphytometer
Steer Creek, Oregon
Dr. Richard KieslingUS Geological Survey8027 Exchange DriveAustin, TX 78754