Hydrology, Hydrology, Topography, and SoilsTopography, and Soils

of of

Lower Suwannee River Lower Suwannee River Floodplain Forests Floodplain Forests

andand

Ecological Consequences of Ecological Consequences of Potential Flow ReductionsPotential Flow Reductions

Helen Light

U.S. Geological Survey

Gulfof

Mexico

At

la

nt

ic

Oc

ea

n

Suw

anne

e

FeRiver

Satn a

Withlacoochee

River

Al

ap

haa

River

River

Study AreaN

Gulfof

Mexico

At

la

nt

ic

Oc

ea

n

Suw

anne

e

FeRiver

Satn a

Withlacoochee

River

Al

ap

haa

River

River

Study AreaNN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Goals

N

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

RIVER HYDROLOGY

FLOODPLAIN HYDROLOGY

FORESTCOMPOSITION

FLOW-DEPENDENTFACTORS

IMPACTS OF FLOWREDUCTIONS

FORESTDISTRIBUTION

TOPOGRAPHY SOILS

HydrologyN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Topography

Soils

TopographyN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Range 11 feet

Levees & ridges prominent

Range 3 feet Levees minor or absent

Hummocks commonTidal creeks common

SoilsN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Mineral soils

Saturated muck

Saturated muckSaline

Floodplain InundationN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Floodplain InundationN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Flow dependent at all flows

Flow dependent at high flows

Little or no relation to flow

Goals

N

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

RIVER HYDROLOGY

FLOODPLAIN HYDROLOGY

FORESTCOMPOSITION

FLOW-DEPENDENTFACTORS

IMPACTS OF FLOWREDUCTIONS

FORESTDISTRIBUTION

TOPOGRAPHY SOILS

Flow Dependent FactorsN

RiverinRiverinee

LowerLowerTidalTidal

UpperUpperTidalTidal

Flood depthsInundationSaturation

Flood depthsInundation

Salinity

Flood depths affects composition by limiting seedling survival

Floodplain Cross Section

High water

Aquatic habitat in floodplain is flow dependent

Inundated Area in Relation to Flow (Riverine)

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

0 5,000 10,000 15,000 20,000 25,000 30,000

FLOW, IN CFS

INU

ND

AT

ED

AR

EA

, IN

AC

RE

S

Loss of Forests at Tree Line

OPEN WATERMARSHESSWAMP

HAMMOCKAQUATIC BEDSSWAMPS REPLACED BY MARSH

Ecological Consequences of Flow Reductions

Forest composition changes:

Exotic species Opportunistic species Human disturbance Lower quality of BLH Fewer wet swamps Forest mortality at tree line

Ecological Consequences of Flow Reductions

Decreased inundation and saturation:

Aquatic habitat for fishes & invertebrates

Nutrient and detritus transport Nitrate removal Water retention during

droughts Vulnerability to fire