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Climate Informed Decision Tools for a Multi-use Reservoir:
The case of Angat and Manila, Philippines
Casey Brown, Sankar Arumugam and Upmanu Lall
The International Research Institute for Climate and Society and
Columbia University
Outline
•Climate and Water Resources Risk in Manila
•Decision Tool for Water Allocation – using seasonal forecast
•Dry-year Option Contracts
•Conclusion – Climate Risk Management for Water Managers–Building Resilience Systems
Northeast Monsoon (Oct – Dec)
Inflow to Angat Reservoir
0
50
100
150
200
250
300
350
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Month
Stre
amflo
w (i
n hm
3)
0
50
100
150
200
250
300
350
400
450
500
Rai
nfal
l (m
m)
StreamflowRainfall
3-months lag correlation
ρ(Nino3.4,QJJAS) = -0.20
ρ(Nino3.4,QOND) = -0.51
JJAS – 30%
OND – 46%
Seasonal Climate Forecast
Angat Reservoir – Manila Water Supply
A aerial view of the Angat Hydroelectric Plant
Courtesy of Mr. Rodolfo German (Angat dam)
Reservoir ManagementHydropower
Water Delivery
Storage
SpillForecast
of Inflows
0
1020
3040
50
6070
8090
100
1 2 3 4 5 6 7 8 9 10 11 12
Critical Months for Water Management
0
1
2
3
4
5
6
7
8
9
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Months
Num
ber o
f yea
rs o
f Spi
lls
Number of years of spills
Angat Decision RuleANGAT H.E. PLANT
150
160
170
180
190
200
210
220
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
ELEV
ATI
ON
(m)
1996 1997 1998 1999 2000 2001 UPPER LOWER
0
1020
3040
50
6070
8090
100
1 2 3 4 5 6 7 8 9 10 11 12
Dynamic Rule Curve
Inflow
Flood
Dry Forecast
0
10
2030
40
50
60
7080
90
100
1 2 3 4 5 6
Less Inflow
Less Flood Risk
More Storage Possible
0102030405060708090
100
1 2 3 4 5 6
More Inflow
Greater Flood Risk
More Release Possible
Wet Forecast
Decision Tool for Water Management
Seasonal Inflow Forecast
Increased Hydropower
0
200
400
600
800
1000
1200
1400
1987 1989 1991 1993 1995 1997 1999 2001
Year
Hyd
ropo
wer
Gen
erat
ed (
in G
WH
)
0
50
100
150
200
250
300
350
400
Observed In
flow
ActualUpdated ForecastOctober ForecastObserved
Irrigation Improvement
0
50
100
150
200
250
1987 1989 1991 1993 1994 1997Year
Allo
cati
on f
or I
rrig
atio
n (
in h
m3
) DecemberNovemberOctober
Current Reservoir Contents
Remaining Water:Agriculture and Hydropower
First Priority: Manila Water
Urban Centers
Low Inflow
“Business as Usual”
Current ReservoirContents
Probabilistic Inflow Forecast
Dry Year Option Contracts
Contractsw/
Dry Year Option
• Building Resilience Systems– Seasonal Climate forecasts
• Early Warnings of Drought, Flood– Decision Support– Economic mechanisms
• Dry year option/insurance
• Better outcomes– Maximize the “good” years– Reduce risk exposure in dry years
Climate Risk Management for Water Managers
Thank You!
•• Thank you!Thank you!