The Impact of Future Climate Variability on the Hydrology ... · The Impact of Future Climate...
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The Impact of Future Climate Variability on the Hydrology of the Delaware River Basin Timothy W. Hawkins Shippensburg University 2018 AWRA Annual Meeting
Transcript of The Impact of Future Climate Variability on the Hydrology ... · The Impact of Future Climate...
The Impact of Future Climate Variability on the Hydrology of the
Delaware River Basin
Timothy W. Hawkins
Shippensburg University
2018 AWRA Annual Meeting
Outline
• Delaware River Watershed
• Model description
• Climate projections
• Model assessment
• Hydrologic projections
Delaware Bay and Watershed
• Watershed: 35,066 km2
• Bay: 2,025 km2
• Main Stem: 330 miles (undammed)
• Tributaries: 216; 14,057 miles
• States: NY, PA, NJ, DE
• Counties: 42; Municipalities: 838
• Water supply: 15 million people
• Watershed: $22.5 billion/year
• Port: $19 billion/ year
https://www.state.nj.us/drbc/
Climate Change and the Watershed
9
11
13
15
1950 2000 2050 2100
Tem
per
atu
re (
°C)
rcp2.6
rcp4.5
rcp6.0
rcp8.5
Modeling the Watershed
• 864 grid cells– 1/8° (~12 km x 12 km)– 141 water cells– 225 watershed cells
• Monthly time step• Development: 1950 – 1999 • Projections: 1950-2099
Gridded Parameters and Constants
• Lat, Lon, area
• Average monthly day length
• Elevation
• Subsurface storage
• Land use land cover
Outputs
• Monthly average temperature (T; °C)
• Monthly total precipitation (P; mm)
• Rainfall (Prain)• Snowfall (Psnow)• Snowmelt (Melt)• Snowcover (Snow)• Available water (Pavail)• Potential ET (PE)• Actual ET (AE)• Subsurface Moisture (SM)• Surplus water (S)• Runoff (RO)
All outputs in mm
Inputs
Monthly Gridded Inputs
• 231 CMIP5 projections
– 1/8° (~12 km x 12 km) statistically downscaled T & P
– Monthly 1950 – 2099
– 37 models; 4 RCP; several runs
• Observed T and P 1950 – 1999 for validation
– Used for hydrologic model development
Model Workflow
1. Differentiate rainfall/snowfall f (T)
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
5. Hamon PE constrained
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
5. Hamon PE constrained
6. Subsurface moisture f (PE, Pavail , capacity, LULC)
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
5. Hamon PE constrained
6. Subsurface moisture f (PE, Pavail, capacity, LULC)
7. Surplus water
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
5. Hamon PE constrained
6. Subsurface moisture f (PE, Pavail, capacity , LULC)
7. Surplus water
8. AE f (PE, Pavail , SM)
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
5. Hamon PE constrained
6. Subsurface moisture f (PE, Pavail, capacity , LULC)
7. Surplus water
8. AE f (PE, Pavail, SM)
9. Runoff f (surplus, LULC)
Model Workflow
1. Differentiate rainfall/snowfall f (T)
2. Snowmelt based on f (T)
3. Accumulate snow water storage
4. Available water from melt and rainfall
5. Hamon PE constrained
6. Subsurface moisture f (PE, Pavail, capacity , LULC)
7. Surplus water
8. AE f (PE, Pavail, SM)
9. Runoff f (surplus, LULC)
10. Aggregate RO for subwatersheds
8
10
Model Evaluation
Gage 8 Gage 10 Whole Basin
Model Evaluation
Gag
e 8
Gag
e 1
0
12
-gag
e a
vg
Monthly r 0.896 0.912 0.855
r sig 0.000 0.000 0.000
NS 0.803 0.824 0.593
Annual r 0.981 0.972 0.944
r sig 0.000 0.000 0.000
NS 0.962 0.918 0.721
8
10
Model Results
Model Results
Model Results
Model Results
Model Results
Model Results
Model Results
Percent Change between Future
and BaselineRCP
2.6
RCP
4.5
RCP
6.0
RCP
8.5
T (°C) 1.9 2.8 3.1 4.5
PE (mm) 58.4 78.4 107.1 99.5
AE (mm) 49.1 64.5 84.0 76.7
SM (%) -2.1 -3.3 -5.4 -5.0
RO (mm) 48.9 51.5 41.0 72.7
P (mm) 98.1 116.3 125.6 150.0
Pr (mm) 132.4 162.1 172.1 212.6
Ps (mm) -34.3 -45.7 -46.5 -62.5
SWE (mm) -3.9 -4.8 -4.8 -5.9
Melt (mm) -34.3 -45.7 -46.5 -62.5
Trends per Century
Percent Change between Future
and BaselineRCP
2.6
RCP
4.5
RCP
6.0
RCP
8.5
T (°C) 1.9 2.8 3.1 4.5
PE (mm) 58.4 78.4 107.1 99.5
AE (mm) 49.1 64.5 84.0 76.7
SM (%) -2.1 -3.3 -5.4 -5.0
RO (mm) 48.9 51.5 41.0 72.7
P (mm) 98.1 116.3 125.6 150.0
Pr (mm) 132.4 162.1 172.1 212.6
Ps (mm) -34.3 -45.7 -46.5 -62.5
SWE (mm) -3.9 -4.8 -4.8 -5.9
Melt (mm) -34.3 -45.7 -46.5 -62.5
Trends per Century
Percent Change between Future
and BaselineRCP
2.6
RCP
4.5
RCP
6.0
RCP
8.5
T (°C) 1.9 2.8 3.1 4.5
PE (mm) 58.4 78.4 107.1 99.5
AE (mm) 49.1 64.5 84.0 76.7
SM (%) -2.1 -3.3 -5.4 -5.0
RO (mm) 48.9 51.5 41.0 72.7
P (mm) 98.1 116.3 125.6 150.0
Pr (mm) 132.4 162.1 172.1 212.6
Ps (mm) -34.3 -45.7 -46.5 -62.5
SWE (mm) -3.9 -4.8 -4.8 -5.9
Melt (mm) -34.3 -45.7 -46.5 -62.5
Trends per Century
Percent Change between Future
and BaselineRCP
2.6
RCP
4.5
RCP
6.0
RCP
8.5
T (°C) 1.9 2.8 3.1 4.5
PE (mm) 58.4 78.4 107.1 99.5
AE (mm) 49.1 64.5 84.0 76.7
SM (%) -2.1 -3.3 -5.4 -5.0
RO (mm) 48.9 51.5 41.0 72.7
P (mm) 98.1 116.3 125.6 150.0
Pr (mm) 132.4 162.1 172.1 212.6
Ps (mm) -34.3 -45.7 -46.5 -62.5
SWE (mm) -3.9 -4.8 -4.8 -5.9
Melt (mm) -34.3 -45.7 -46.5 -62.5
Trends per Century
Percent Change between Future
and BaselineRCP
2.6
RCP
4.5
RCP
6.0
RCP
8.5
T (°C) 1.9 2.8 3.1 4.5
PE (mm) 58.4 78.4 107.1 99.5
AE (mm) 49.1 64.5 84.0 76.7
SM (%) -2.1 -3.3 -5.4 -5.0
RO (mm) 48.9 51.5 41.0 72.7
P (mm) 98.1 116.3 125.6 150.0
Pr (mm) 132.4 162.1 172.1 212.6
Ps (mm) -34.3 -45.7 -46.5 -62.5
SWE (mm) -3.9 -4.8 -4.8 -5.9
Melt (mm) -34.3 -45.7 -46.5 -62.5
Trends per Century
Percent Change between Future
and BaselineRCP
2.6
RCP
4.5
RCP
6.0
RCP
8.5
T (°C) 1.9 2.8 3.1 4.5
PE (mm) 58.4 78.4 107.1 99.5
AE (mm) 49.1 64.5 84.0 76.7
SM (%) -2.1 -3.3 -5.4 -5.0
RO (mm) 48.9 51.5 41.0 72.7
P (mm) 98.1 116.3 125.6 150.0
Pr (mm) 132.4 162.1 172.1 212.6
Ps (mm) -34.3 -45.7 -46.5 -62.5
SWE (mm) -3.9 -4.8 -4.8 -5.9
Melt (mm) -34.3 -45.7 -46.5 -62.5
Trends per Century
Modeled DJF Snow Cover
Distribution of Modeled Runoff
Conclusions
• Basin-wide increases– T, P, Pr , PE, AE, RO
• Basin-wide decreases– Ps , SWE, melt, SM
• High spatial variability
• Runoff as an integrator– Increasing 3.5 – 17.4%
• most under rcp 8.5
– Increasing in winter
– Range in projections
– PE calculation matters
Future Work
• Impact on flood hydrology
• Impact on tree species
• Repeat analysis at 800 m resolution
• Examine drought and surplus conditions
Questions?
https://centerforlanduse.org/projects/drb/
AcknowledgementsAlfonso Yáñez, Jonathon Chester, Troy Pomeroy, Antonia Price, Claire Jantz, Christopher Woltemade, Scott Drzyzga, Patrick Jantz
Impact of Constraining PE
• Energy Only– Simple proportion
based on LE and H
• 7 traditional ET’s
• ET calculations reasonable
• ET future changes not reasonable except for energy only
Milly and Dunne (2017)
Impact of Constraining PE
• Calculate Hamon and Energy only for GCM’s– 1 cell for DRB, monthly 1950-2099
• Calculate Hamon diff between future downscaled and historic GCM
• If Hamon difference > GCM Energy Only:– PE = Historic Hamon + Energy Only diff +
diff btw downscaled PE and running mean
• Take home message: – Statistically constrained runaway PE– Accounts for increased stomatal resistance w/
warmer temperatures.
Impact of Constraining PE
