Transcript Modeling Flood Control Flexibility using the GENESYS Hydro

Modeling Flood Control
Flexibility using the
GENESYS Hydro Model
Kyle Martin
Mainstem Hydrologist
Columbia River InterTribal Fish Commission
Portland, Oregon
Introduction
• A natural river reservoir operation promotes
environmental conditions that are in harmony
with the salmon’s biological timing. (Return of
the River…Independent Science Group, 1996,
http://www.nwppc.org/return_toc.htm)
• Altered flood control and earlier reservoir refill
can achieve a more natural flow regime.
Natural Hydrograph Concept
• Natural flow regimes enhance salmon survival
with: increased turbidity, decreased travel time,
increased habitat, higher river and estuary
productivity.
• More water is shifted from winter to late spring.
Outflows modeled at minimum through May.
• Altered Flood Control uses less drafts during
late winter and early spring. Strategy takes
advantage of expected global warming.
GENESYS Hydro-generation model
• This NPPC model uses monthly time steps.
• Flow operations are specified at all PNW dams.
• Model runs sequentially from dam-to-dam.
• Record spans Water Years 1929 - 1978.
• Output: flow, pool elevations, generation.
• New encoded storage Rule Curves can alter
flood control operations.
GENESYS
Energy Analyses, Economics
PLANT File:
Physical Characteristics-Min/Max flow, FB vs. Storage
Tail-Water vs. Discharge
Multi-Dam Stand-Alone
(Hydro-Sim model)
PERIOD File:
Rule Curves
OPERATIONS Files:
Flow Limits, Spill, Storage Limits
“Operation-Exception”
Program Control Files-- Pre-Processing
50 years historical, observed data
Proportional draft, PNCA specified
GENESYS
Multi-Dam
Prioritized operating parameters
Draft specific reservoirs, if desired
Program Control Files-- Post-Processing
Graphical Displays:
Outflow, Pool Elevations, Storage
Tabular Reports and Data Files
Altered Flood Control
• Global warming will reduce winter snow packs.
Spring flood control drafts can be reduced.
• Reservoir refill probability increases.
• As reservoirs fill by May 31, excess inflow is
passed and generates a higher seasonal peak.
• Altered flood control reclaims 5.55 MaF at
Grand Coulee, 2.7 MaF at Dworshak, & 0.35
MaF at Brownlee (total: 8.6 MaF).
• Advanced river forecasting tools (eg, UW-DHSV
or NWSRFS) can reduce premature FC drafts.
Results of Natural River plan
using GENESYS model
• Average (50-year) June peak at The Dalles is
375 kcfs. Current operational peak is 280 kcfs.
High water year peak is 445 kcfs (21 years).
Low water year peak is 245 kcfs (11 years).
• Summer flows will increase by 18%. Winter
flows may decrease by 20%.
• Flood control maxima averages 1540 feet at
Dworshak, 2055 feet at Brownlee, and 1265
feet at Grand Coulee.
Elevation (feet)
Grand Coulee pool: 50 year average
1,290
1,288
1,286
1,284
1,282
1,280
1,278
1,276
1,274
1,272
1,270
1,268
1,266
1,264
1,262
1,260
1,258
1,256
1,254
1,252
1,250
1,248
1,246
1,244
1,242
1,240
OCT
NOV
DEC
JAN
FEB
MAR
Federal Operations
AP1
AP2
MAY
JUN
JUL
AG1
CRITFC Natural-Peak
AG2
SEP
Elevation (feet)
Dworshak pool: 50 year average
1,600
1,595
1,590
1,585
1,580
1,575
1,570
1,565
1,560
1,555
1,550
1,545
1,540
1,535
1,530
1,525
1,520
1,515
1,510
1,505
1,500
OCT
NOV
DEC
Federal Operations
JAN
FEB
MAR
AP1
AP2
MAY
CRITFC Natural-Peak
JUN
JUL
AG1
AG2
SEP
Flows (cfs)
The Dalles: 50 year average
500,000
480,000
460,000
440,000
420,000
400,000
380,000
360,000
340,000
320,000
300,000
280,000
260,000
240,000
220,000
200,000
180,000
160,000
140,000
120,000
100,000
80,000
60,000
OCT
NOV
DEC
Priest Rapids Dam Outflow
Historical Observed (1900-1920)
JAN
FEB
MAR
AP1
AP2
Federal Operations
Bankfull (Portland / Vancouver)
MAY
JUN
JUL
AG1
CRITFC Natural-Peak
AG2
SEP
Benefits to Northwest Salmon
• Enhanced ecosystem health and diversity.
Resident fish populations enjoy more habitat.
• Speed juvenile migrants to the estuary.
• Transport more woody and organic debris.
• Less predation. Cooler passage water.
• Increase estuary plume--critical habitat.
• Provide adequate flow for returning adults.
Currently, flows are low in September.
How a Natural River plan may
Impact the Pacific Northwest
• More salmon return to spawn while Columbia
Tribal treaties are honored.
• Flood risk to Portland is 18% (versus 10%). Top
5 years average to 550 kcfs flood flow. A 600
kcfs flood flow gives 10% risk versus 6%.
• Spring flood risk mitigated by global warming.
• Less winter generation will be offset by higher
summer generation (June-September).
Spring Flood-Frequency (WY 1929-78): Columbia River at The Dalles
Flow (cfs)
1,000,000
100,000
2
6
10
13
17
21
25
29
33
37
40
44
48
52
56
60
63
67
71
75
79
83
87
90
94
Probability of flow being equaled or exceeded
Historical Observed peak
Federal Operation peak
Bank Full
Flood Flow
CRITFC Natural Hydrograph peak
Summary
• Altered flood control can reclaim 8.6 MaF of
storage to benefit salmon resources while
restoring the Columbia and Snake rivers back to
a natural peaking hydrograph. River and
estuary habitat would improve.
• Natural River plan shifts winter flow into spring,
refills by May 31st, and passes inflow in June.
Flood risk increases from 10% to 18% but will
decrease as global climate warming continues.
• Need to run daily flood risk & life-cycle studies.