Reconciling Floodplain Reconnection and Agricultural Land...

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)


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


10k cfs Flow Scenario(Delta Vision, 2010)

Legend

Alfalfa

Almonds

Truck Crops


Dairy

Fallow and Idle

Grapes

Native Vegetation

Pasture

Tomatoes

Urban

Walnuts

Water

*Assuming full

levee removal



Legend

Alfalfa

Almonds

Truck Crops


Dairy

Fallow and Idle

Grapes

Native Vegetation

Pasture

Tomatoes

Urban

Walnuts

Water

10,000 cfs flow 15,000 cfs flow



Legend

Alfalfa

Almonds

Truck Crops


Dairy

Fallow and Idle

Grapes

Native Vegetation

Pasture

Tomatoes

Urban

Walnuts

Water



Legend

Alfalfa

Almonds

Truck Crops


Dairy

Fallow and Idle

Grapes

Native Vegetation

Pasture

Tomatoes

Urban

Walnuts

Water



Full Setback Area(Delta Vision, 2010)

Legend

Alfalfa

Almonds

Truck Crops


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



., • 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?

[email protected]

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.

mailto:[email protected]



$-

$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.

Reconciling Floodplain Reconnection and Agricultural Land...

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