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Large River Flood Pulse. Where Are We?. Ponchartrain. Atchafalaya. N. Barataria. Terrebonne. Habitat Types of the Barataria-Terrebonne Basins. The Floodplain Extends to the Coast. All flowing Louisiana waterways eventually drain to the Gulf of Mexico

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slide2

Where Are We?

Ponchartrain

Atchafalaya

N

Barataria

Terrebonne

the floodplain extends to the coast
The Floodplain Extends to the Coast
  • All flowing Louisiana waterways eventually drain to the Gulf of Mexico
  • How much are energy and nutrients transferred throughout the estuary?
  • Is the coast is ultimately supported by floodplain ecosystem processes
slide6

Estuaries

Swamps and marshes

Tropical rain forest

Temperate forest

Northern coniferous forest (taiga)

Savanna

Agricultural land

Woodland and shrubland

Temperate grassland

Lakes and streams

Continental shelf

Open ocean

Tundra (arctic and alpine)

Desert scrub

Extreme desert

800

1,600

2,400

3,200

4,000

4,800

5,600

6,400

7,200

8,000

8,800

9,600

Average net primary productivity (kcal/m2/yr)

Net Primary Production

(measure of available energy and nutrients)

(Miller, G.T. 2002. Living in the Environment: Principles, Connections, and Solutions)

stream order

1

1

1

1

2

2

1

2

3

Stream Order – Strahler Method

Stream Order

Used to classify a stream in relation to tributaries, drainage area, total length, and age of water.

1  1 = 2

1  2 = 2

2  2 = 3

1  3 = 3

2  3 = 3

3  3 = 4

Mississippi River is classified as a 10th or 12th order stream.

Headwater stream classification matters

rivers and streams
Rivers and Streams
  • Generally represent the excess of precipitation on land areas over evaporation from them.
    • Precipitation that falls is either evaporated, transpirated, enters the ground water supply, or flows down rivers
  • Flow is down-hill and varies seasonally
    • Related to rainfall and ice/snow melt
  • Beginning of a river = the source and the end of a river = the mouth
  • Discharge - volume of water passing a given point during a period of time
    • Channel Width X Depth X Velocity
rivers and streams1
Rivers and Streams
  • Materials are transported by running water in three principal states
    • Dissolved matter
    • Suspended solids
    • Bed load
  • Allochthonous – organic material brought in from outside the system
  • Autochthounous – organic material produced within the system (primary production)
slide12

Maringouin: 6,000 – 7,000 years ago Teche: 5,700 – 3,900 years ago St. Bernard Delta: 4,600 – 1,800 years ago Lafourche Delta: 3,400 - 400

slide13

Construction of levees along the Mississippi River and many of its tributaries has severed the river from over 90% of its floodplain, denying fish and other aquatic species access to millions of acres of foraging, spawning and nursery habitat.

Miss. Dept. of Archives and History

Miss. Dept. of Archives and History

http://www.lmrcc.org/ARMP%20folio.pdf

the flood pulse

= Average Stage

= 2005 Stage

The Flood Pulse

1959-2005 Atchafalaya River Stage at Butte La Rose USACE Gage ID = 03120

slide15

April

February

December

September

slide16

April

June

August

September

floodplain zones

I

II

III

IV

V

VI

Floodplain Upland Transition

Active Floodplain

Aquatic Ecosystem

Terrestrial Or Upland Ecosystem

Bottomland Hardwood Ecosystem

Floodplain System

Floodplain Zones

From Larson et al. 1981; Hall and Lambou 1990

slide18

Atchafalaya River Basin

Distributary – A smaller channel that takes water away from the main stem river.

Flow

Mississippi River (Main Stem)

Atchafalaya River (Distributary)

arb cross section
ARB Cross Section

Protection Levees

Natural Levees

Floodplain

Floodplain

Atchafalaya River

Back Water Area

Back Water Area

floodplain
Floodplain

Deer Lake

Billy Littles Lake

slide24

Staff Gage

Water Level

Floodplain

Bank Full Level = 66 ± 9.5 cm

AR = 218 cm (7.15 ft)

Lake

three general types of water
Three General Types of Water
  • Brown
    • High flow, lots of sediment, fairly high oxygen levels, riverine
  • Green
    • Low flow, stratification, very high surface oxygen levels, highly productive, lacustrine
  • Black
    • Low flow, very low surface oxygen levels, not productive, swamp
slide27

Backwater

Interior Lakes

Mainstem

December

June

August

what is hypoxia
What is Hypoxia
  • Dissolved Oxygen less than 2.0 mg/L
  • Normoxic = DO > 2.0 mg/L
  • Generally, most fish can not tolerate hypoxic conditions for long periods.
    • Gar, bowfin (choupique), bullheads can
when and where is hypoxia
When and Where Is Hypoxia?
  • Generally found during high water times when temperatures are warm.
  • Backwater areas (away from the mainstem river).
    • Low flow
oxygen level controls
Oxygen Level Controls

Photosynthesis produces oxygen:

Solar Energy + CO2 + H20  C6H12O6 + O2

Respiration consumes oxygen:

C6H12O6 + O2 CO2 + H20 + chemical energy(ATP)

aquatic terrestrial transition zone attz
Aquatic/Terrestrial Transition Zone (ATTZ)
  • Alternates between aquatic and terrestrial habitats (active floodplain).
  • Important for fish feeding and reproduction.
  • Facilitates transfer of energy and nutrients between aquatic and terrestrial habitats.
slide33

Terrestrial Vegetation Growth During Low Water

Nutrients Released During High Water

slide34

= Happy Cajuns!!

Simply put:

More Nutrients = More Plants = More Animals

Inundation of the floodplain is the mechanism of energy and nutrient transfer from terrestrial vegetation to the aquatic community.

slide38

8

9

7

6

slide39

How Do ‘Unproductive’ Areas Support Living Populations?

  • Detritus-Based Production
    • Decomposers (e.g., bacteria) transfer energy stored in old organic matter to consumers
      • Insects, crawfish
    • Low-oxygen tolerant organisms
      • Gar, bowfin (choupique), bullheads
slide40

Energy flow through an aquatic ecosystem.

From Cole 1988, Waveland Press

what if there is no flood pulse
What If There is no Flood Pulse?
  • Barataria-Terrebonne National Estuary has been cut-off from the Mississippi River
  • Hydrology is strictly related to local precipitation
    • What are the possible implications in light of the Flood Pulse Concept?
slide43

No More Flood Pulse

Ponchartrain

Atchafalaya

Barataria

Terrebonne