Upload
phammien
View
220
Download
0
Embed Size (px)
Citation preview
Reconciling Floodplain
Reconnection and Agricultural
Land Use
Alejo Kraus-Polk Geography UCD, IGERT Fellow
American Rivers
John Cain
American Rivers
Bay-Delta Science Conference
October 29, 2014
Recent Applications of the Estimated Annual Floodplain Habitat (EAH) Method to Measure, Evaluate, and Design Floodplain Habitat
John Cain, American Rivers
J Background Until recently, the lack of replicable methods for measuring floodplain habitat has limited the ability of managers to evaluate historic changes in the quantity of floodplain habitat or plan and design floodplain restoration projects. The development of hydraulic models and high resolution topographic data developed as part of the Central Valley Flood Protection Plan has facilitated the development of the expected annual habitat (EAH) method (Matella and Jagt, 2013) (see poster by Matella et al.), which in turn has enabled managers to plan and evaluate a broad range of floodplain restoration projects. The EAH method can quantify the floodplain habitat effects of any project that either modifies hydrology or floodway geometry. Aside from the data and hydraulic modeling issues that arise in any flood management study, the calculation of EAH is transparent and replicable. Calculation of inundated area and frequency of inundation is based solely on stage discharge relationships and standard frequency analysis statistics. EAH is therefore a replicable, scientific method that is not subject to distortions associated with weighting factors or professional opinion. American Rivers, a national river conservation organization, has worked with scientists, engineers, and planners to develop the EAH for a range of applications across the Central Valley. These include use of the EAH to measure the existing area of floodplain habitat in the Central Valley (see Jagt poster), estimate the amount of floodplain habitat necessary to double anadromous fish populations (see poster by Tompkins et al.), quantify the floodplain habitat characteristics of the Southport levee set-back project in West Sacramento, evaluate floodplain management conflicts in the Yolo bypass (Jagt et al. presentation Thursday at 3:20), measure the floodplain benefits of levee set-back and flow augmentation scenarios on the lower San Joaquin, and predict the agro-economic impacts of removing levees on the lower San Joaquin River (Kraus-Polk presentation Thursday at 3:40).
CBEC utilized the EAH method to generate area duration frequency (ADF) curves for West Sacramento Area Flood Control Agency’s proposed project to set-back the west levee in an urbanized reach of the Sacramento River. These preliminary results indicate that the area waterward of the new setback levee will provide frequently inundated habitat because the project entails expansion of the floodplain and increased connectivity to the river. Design shown is conceptual for illustrative purposes
only. Actual layout and connections to the river are subject to refinement in final design.
West Sacramento Levee Setback
Central Valley Flood Protection Plan Conservation Strategy
The Department of Water Resources has proposed using the EAH has a foundational metric to measure the floodplain benefit or impact of proposed flood system modifications that may occur as part of the Central Valley Flood Protection Plan.
From DWR Technical Workshop: Getting to Measureable Objectives (May 2013)
Flood System Planning Areas
Rapid Scenario Evaluation in the Yolo Bypass and Elsewhere
Waterfowl (15 day
duration)
Mid August thru Late
March
Ba
seline
w/o
ut W
est Sid
e Trib
s
2-YR10-YR
Winter Run
Chinook (14 day
duration)
Mid November thru
Late March
Maximum Area with Notch Flow Limited to
6,000 cfs
Preliminary Results for Illustrative Purposes American Rivers and Newfields have developed a tool that automates the EAH method for rapid scenario screening in the Yolo Bypass and in any other locations where the user can provide basic hydrology and hydraulic data. The tool allows planners to quickly determine how changes in hydrology or floodway geometry will change the timing, duration, and frequency of inundation. Results above are preliminary and likely to change significantly when the scenarios are evaluated with new hydrologic inputs including westside tributaries. Furthermore, the watefowl results are problematic because they do not consider managed wetlands that constitute the majority of existing habitat in the bypass.
How Much Floodplain Habitat do Salmon Need?
Newfields, Cramer Fish Sciences, and DWR utilized EAH to estimate the area of historical and existing suitable rearing habitat area for juvenile salmonids. They used the ESHE model to calculate the amount necessary to achieve AFRP the doubling goal. (See poster by Tompkins et al. for more detail)
Crops inundated with 20k cfs on lower San Joaquin assuming full levee removal and predicted economic losses from inundation.
Can Floodplain Habitat and Agriculture Co-Exist?
American Rivers and Alejo Kraus-Polk utilized the EAH to estimate the probability of inundation for various crops assuming full levee removal between Vernalis and Mossdale. They then multiplied the probability of inundation by the gross crop revenue to generate an annualized costs to agriculture of full levee removal. The probability of inundation and associated crop damage is relatively low due to the severe hydrologic regulation from upstream reservoirs that were built after the levees.
How Much Frequently Inundated Floodplain is There?
With support from the California Water Foundation, American Rivers and Katie Jagt utilized the EAH method to calculate the total amount of inundated floodplain habitat for a variety of species. CBEC provided hydraulic data with J-flow model. These results can be used to compare with Tompkins (above), provide baseline values to measure restoration progress, and evaluate the relative contribution of proposed restoration projects. (see Jagt poster)
8,955
2,823 4,390 622 468
5,588 8,953
57,805
382
15,934
1,965 795 -
10,000
20,000
30,000
40,000
50,000
60,000
(acr
es)
General EAH - 14 Days Dec.-May in 50% of Years
Tompkins et. al, 2014; Carson Jeffries, 2011
80,000
-"' GI ... v 70,000 "' -c 0 E ii II)
~ 0 0
60,000
c :E u ~ ·c: 50,000 GI
Suitable rearing habitat > ::s ..... creation required to support ...
0 .... the Doubling Goal "' GI 40,000 ... ct .. "' .. :a "' :::c bl) 30,000 c
·;::::
"' GI a:: GI
::c 20,000 "' .t:: ::s II)
10,000
Upper Sacramento River Lower Sacramento River Feather River Lower San Joaquin River
Conservation Strategy Region
• Historica l Suitable Rearing Habitat • Existing Su itable Rearing Habitat • Requ ired Suitable Rearing Habitat
Floodplain area in the
lower SJ is limited by
• Levees
• Regulation by
upstream reservoirs
• Upstream diversions
American Rivers (2013)
Options for restoring floodplains:
1. Remove or setback levees
2. Increase flows
3. Lower floodplains between levees
4. Raise channel invert*
Raise channel invert
• Raising channel invert not possible within regulatory floodway, thus may require levee setback/removal.
• Would allow for floodplain inundation with significantly less flow.
http://fishbio.com/projects/honolulu-bar-
restoration-and-floodplain-enhancement
“ECOLOGICAL
POP PER DROP”
• Levees were built prior to the
construction of upstream
reservoirs.
• Upstream reservoirs
significantly reduce flood
frequency.
• Large, infrequent floods
continue to create problems
such as levee failures and
seepage.
Historical Background
FEMA 100-year
levees (yellow-red)
Non-project levees
(red)
Shaded blue denotes area subject to
1% annual chance (100 year event)
flood
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
Historical Ecology
Legend
Habitat Type
open water
fluvial open water
intermittent pond/lake
non-tidal freshwater emergent wetland
valley foothill riparian
wet meadow/seasonal wetland
alkali seasonal wetland complex
grassland
oak woodland/savanna
Historical Ecology (Whipple, 2012)
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
Full Setback Area(Delta Vision, 2010)
Legend
Alfalfa
Almonds
Truck Crops
Livestock Feed (Green Chop)
Dairy
Fallow and Idle
Grapes
Native Vegetation
Pasture
Tomatoes
Urban
Walnuts
Water
Crop Map (2010)
-----CJ ---- -- -- /
Research Questions Lower San Joaquin River Bypass
What would be the economic impact to agriculture if there were no levees between Vernalis and I-5?
Conversely…
What economic benefits do the levees provide ?
Method
• We utilized hydrologic model results to generate inundated area maps for different discharge scenarios.
• We adapted the Estimated Annual Habitat method (EAH) to quantify probability of inundation for various cultivated crops.
• We then multiplied probability of inundation by crop production value to calculate risk (annualized gross revenue foregone).
Spatial and temporal
characteristics of inundation
Area
Duration
Frequency
Agronomic information related
to crop acreage, planting
schedules, flood tolerance,
and production value.
Method
0
5,000
10,000
15,000
20,000
25,000
30,000
8 18 28
Vern
alis F
low
s (
cfs
)
Exceedance Probability
FEB MAR
APR MAY
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
10k cfs Flow Scenario(Delta Vision, 2010)
Legend
Alfalfa
Almonds
Truck Crops
Livestock Feed (Green Chop)
Dairy
Fallow and Idle
Grapes
Native Vegetation
Pasture
Tomatoes
Urban
Walnuts
Water
*Assuming full
levee removal
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
15k cfs Flow Scenario(Delta Vision, 2010)
Legend
Alfalfa
Almonds
Truck Crops
Livestock Feed (Green Chop)
Dairy
Fallow and Idle
Grapes
Native Vegetation
Pasture
Tomatoes
Urban
Walnuts
Water
10,000 cfs flow 15,000 cfs flow
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
20k cfs Flow Scenario(Delta Vision, 2010)
Legend
Alfalfa
Almonds
Truck Crops
Livestock Feed (Green Chop)
Dairy
Fallow and Idle
Grapes
Native Vegetation
Pasture
Tomatoes
Urban
Walnuts
Water
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
25k cfs Flow Scenario(Delta Vision, 2010)
Legend
Alfalfa
Almonds
Truck Crops
Livestock Feed (Green Chop)
Dairy
Fallow and Idle
Grapes
Native Vegetation
Pasture
Tomatoes
Urban
Walnuts
Water
20,000 cfs flow 25,000 cfs flow
Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2013
Full Setback Area(Delta Vision, 2010)
Legend
Alfalfa
Almonds
Truck Crops
Livestock Feed (Green Chop)
Dairy
Fallow and Idle
Grapes
Native Vegetation
Pasture
Tomatoes
Urban
Walnuts
Water
A 48,500 cfs flow discharge is
required to inundate the full
setback area.
The 48,500 cfs flow scenario
corresponds to the 50-year flood
event, which has a 2% chance of
occurring in any given year
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
10 15 20 25 50-yr event
Acre
s
Flow Scenario (thousand cfs)
Full setback area (including developed land
and open space) is approximately 10,258
acres.
$0
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
$14,000
$16,000
10 15 20 25 50-yrevent
Pro
du
cti
on
Va
lue
Fo
reg
on
e (
$1
,00
0)
Flow Scenario (thousand cfs)
Approximate Production
Value Forgone
0
500
1000
1500
2000
2500
3000
3500
Oth
er
Hay/N
on A
lfa
lfa
Alfalfa
Oats
Win
ter
Wheat
Alm
ond
s
Waln
uts
Gra
pe
s
Corn
Dbl C
rop
Dry
Beans
Saff
low
er
Sw
eet
Corn
To
mato
es
Acre
s
Crop Type
Crop Acreages in Total Setback Area
Perennials are approximately 10% (2010)
Annual crops with planting flexibility (UCCE San Joaquin)
Non-flood risks: frost, rain, and of course … drought!
Yields and Gross Revenues (2012 $) for Selected Crops
Yields Crop type (Tons/ Gross Revenue/Ton ($) Gross Revenue/ Acre ($)
Acre)
Almonds All 1.03 3740 3852 Walnuts English 2.07 2542 5262 Corn Grain 5.21 206 1073
Corn Silage 31.62 44 1391 Corn Sweet All 7.71 501.01 3863 Grapes Table 5.63 224.26 1263
Grapes Wine 5.6 550.56 3083 Hay Alfalfa 6.24 255 1591 Hay Other Unspecified 3.08 163.01 502
Silage 6.54 34 222 Wheat All 2.91 205.37 598
Tomatoes Fresh Market 13.1 400 5240
Tomatoes Processing 40.51 74 2998
We then multiplied crop value by the frequency that
a given crop area would be inundated to determine
risk.
Risk = annualized gross revenue foregone
We developed a crop vulnerability index, which
conveys the annualized risks associated with
planting time for annual crops.
*Assuming
no adaption
10,000 cfs flow 15,000 cfs flow
20,000 cfs flow 25,000 cfs flow
., • 11,.
Legend Risk Categories
- High Risk
Medium Risk
C Low Risk
•
.. •••
I .. A . Legend
~ \
Risk Categories
High Risk
Medium Risk
C Low Risk
.... .;
·~" s
... it ...... __ ""'·
t-
.,
... ..
• 0
" . I •
l J
.. • "'
S<iura.s. E.ili. Ot!Letme, NAlfrEO. USGS. lnlt!trnao, IPC, NRCAN, Esri .IAl)l.'ln. t.CET~ E!n ClwW {Hofl9 Kong). E9:1 (Thailand}. Torr Ten • 2013
, ..
To determine the vulnerability associated
with planting annuals in a specific month
we calculated vulnerability for that month
and then added the crop vulnerability for
proximate months when annual planting
occurs.
Our assumption being that the risk
associated with an early planting of
annuals must take into consideration risks
of inundation events later in the spring.
FEB MAR APR MAY
Sweet Corn 101 76 50 19
Corn 261 198 131 52
Other Hay/Non Alfalfa 295 225 150 60
Winter Wheat 323 247 164 65
Silage (double crop) 458 350 231 93
Oats 939 806 667 294
Tomatoes 1063 810 536 215
Alfalfa 1645 1245 824 324
0
1,000
2,000
3,000
4,000
5,000
6,000A
rea V
uln
era
ble
(A
cre
s)
Annual Crops - timing matters a great deal
Risk decreases as the season progresses
Similar to the risk management associated with a early spring frost
event.
Tomatoes
$0
$500
$1,000
$1,500
$2,000
$2,500
$3,000
$3,500
FEB MAR APR MAY
An
nu
alized
Pro
du
cti
on
Valu
e F
ore
go
ne
($1,0
00)
Approximate Planting Date
$-
$500
$1,000
$1,500
$2,000
$2,500
$3,000
$3,500
TomatoesSweet Corn CornOther Hay/Non AlfalfaOats
An
nu
ali
ze
d G
ros
s R
eve
nu
e
Fo
reg
on
e (
$1
,00
0)
FEB MAR APR MAY
Expected annualized gross revenue foregone for annual crops by
approximate planting date
Example
Due to extreme hydrograph alteration by upstream dams, the
impact of levee removal on agricultural production value is
limited. For example, a late May 15,000 cfs flood event
(occurring approximately 1 in 7 years) would decrease annual
crop production value by $2.5 million—slightly under one-
tenth of total gross production value ($27m) of the total
setback area.
*not including 300 acres of perennial crops are at risk.
The average annual risk to annual crops of a 15,000 cfs May
event ~ $350,000 per yr
$4,592
$3,515
$2,357
$948
FEB MAR APR MAY
Approximate Planting Date
Annualized Gross Revenues Foregone for Annual Crops by approximate planting date ($1,000)
Results Additional adaptions, such as planting later into
the spring season, have the potential to greatly
reduce risks for annual plantings.
Method
Underestimates
• Ignores field damages and recovery costs
• 2010 data underestimates extent of perennial crops
• Gross revenue foregone is a rough proxy for broader economic impact (doesn’t include multipliers)
• Assumes no crop flood tolerance
• Ignores that growers are currently affected by seepage in wet years
• Assumes full levee removal (vs. strategic)
• HEC-RAS 1D may overextend area of inundation (but seepage
confounds)
• Ignores how growers will adapt cropping patterns and planting times
(for instance not plant in January…)
• Assumes no seasonal foresight
Method
Overestimates
Conclusion
Probability of large areas being inundated after crops
are planted is relatively low due to upstream
regulation.
+
Relative low value crops (2010) are being grown in
the area frequently inundated.
=
Potential risks of revenue loss is relatively low.
Strategically restore significant areas of floodplain
with relatively small impact regional agriculture is
high.
Next steps
How do these costs compare to those
associated with:
• Existing costs of maintaining and operating
levees
• Flood fighting
• Levee failure
• Drainage
• Pumping
• Salinity management
Currently looking for these costs…
Next Steps:
Exploring synergies between agroecosystems
and floodplain restoration.
How can growers benefit from the restoration of
natural floodplain function?
HEC-RAS 2D + Hydrospatial modeling
Groundwater recharge
Tradeoff Compatibility Synergy
Questions?
Special thanks to:
John Cain, Mary Matella, Mark
Tompkins, Josue Medellin-
Azuara, Rene Henery, Julie
Rentner, Chris Unkel, David Doll
Original artwork by Laura Cunningham, 2010.
$-
$200
$400
$600
$800
$1,000
$1,200
$1,400
$1,600
$1,800
$2,000
10k 15k 20k 25k 50-yr event
Pro
du
cti
on
Valu
e F
ore
go
ne (
$1,0
00)
Vines
Walnuts
Almonds
Perennial Crops
Timing does not matter as much
Duration and frequency are more important
Problem:
Floodplain restoration efforts along the
San Joaquin are seen as incompatible
with ongoing agricultural production.