large river flood pulse
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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 - PowerPoint PPT PresentationTRANSCRIPT
Large River Flood Pulse
N
Where Are We?
Barataria
Terrebonne
Ponchartrain
Atchafalaya
Habitat Types of the Barataria-Terrebonne Basins
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
How Connected are the Swamps to the Coast?
Estuary Continuum?
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
11
11
22 22
11
11 11
33 22
Stream Order – Strahler MethodStream Order – Strahler Method
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 = 4Mississippi River is classified as a 10th or 12th order stream.
Headwater stream classification matters
Major Rivers of The World
NameDischarge 103 m3/sec
Length 103 km
Drainage Area 106 km2
Amazon, South America 212.40 6.44 5.78
Congo, Africa 39.65 4.70 4.01
Ganges-Brahmaputra, India 38.50 2.90 1.62
Yangtze, China 21.81 5.98 1.94
Yenisei, USSR 17.39 5.54 2.59
Mississippi, North America 17.30 (6) 6.02 (3) 3.22 (4)
Mekong, Asia 11.04 4.00 0.80
Nile, Africa 3.10 6.65 3.35
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 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)
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
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
1959-2005 Atchafalaya River Stage at Butte La Rose USACE Gage ID = 03120
0
1
2
3
4
5
6
7
8
9
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Avg
. M
on
thly
Riv
er S
tag
e (m
)
= Average Stage
= 2005 Stage
September
December
February
April
AprilJuneAugust
September
Floodplain Zones
From Larson et al. 1981; Hall and Lambou 1990
I II III IV V VI
Aquatic Ecosystem
Active Floodplain
Floodplain Upland Transition
Terrestrial Or Upland Ecosystem
Bottomland Hardwood Ecosystem
Floodplain System
Mississippi River (Main Stem)
Atchafalaya River (Distributary)
Flow
Distributary – A smaller channel that takes water away from the main stem river.
Atchafalaya River Basin
ARB Cross Section
Atchafalaya River
Natural LeveesFloodplain Floodplain
Protection Levees
Back Water Area Back Water Area
FloodplainDeer Lake
Billy Littles Lake
Bank Full Level = 66 ±
9.5 cm
AR = 218 cm (7.15 ft)
Lake
Staff Gage
Floodplain
Water Level
Atchafalaya River Basin
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
Backwater Interior Lakes Mainstem
December
June
August
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?
• Generally found during high water times when temperatures are warm.
• Backwater areas (away from the mainstem river).– Low flow
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)• 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.
Terrestrial Vegetation Growth During Low Water
Nutrients Released During High Water
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.
= Happy Cajuns!!
Eventually the swamp drains and backwater areas become very productive.
Altered Flood Pulse
6
7
8 9
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
Energy flow through an aquatic ecosystem.
From Cole 1988, Waveland Press
Detritus based energy flow through an aquatic ecosystem.
From Cole 1988, Waveland Press
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?
No More Flood Pulse
Barataria
Terrebonne
Ponchartrain
Atchafalaya