USING HYDROLOGY TO COMPARE A REGIONAL HYDROGEOMORPHIC (HGM)

CLASSIFICATION ACROSS A LATITUDINAL GRADIENT OF THE APPALACHIAN

MOUNTAINS

Charles Andrew Cole - Penn State UniversityChris Cirmo - SUNY, Cortland

Denise Wardrop - Penn State UniversityRobert P. Brooks - Penn State UniversityJessica Peterson – Penn State University

Riparian Depressions

NY

PA

VA

1997 HGM key for the Ridge and Valley

• A quick means of identifying HGM subclass• A direct way into the assessment of function• May or may not work anywhere else along the

Appalachian Mountains

• Objective: Use hydrology to assess HGM key north and south along Appalachian Mountains

Hydrogeomorphology

Depression

Slope

Floodplain

Fringing

Flats

Impoundment

Reference Wetlands

• Group of natural wetlands w/in a region

• ‘Pristine’ to disturbed• Used to develop

range of expected conditions

• Problems include:• Lack of good data• Hard to get good data• Need landscape

component• Relationship between

functions and values?

Riparian Depression

• Adjacent to streams

• Surface outlet with unidirectional flow

• No water from overbank flooding

• Soils saturated, rarely flooded

• Low energy systems

• PEM, PSS, PFO

Slope

• On topographic gradient

• Surface and groundwater

• Saturated, rarely inundated

• Low energy systems• PEM, PSS, PFO

Headwater floodplain

• Adjacent to 1st, 2nd order streams

• Not much overbank flooding. Overland flow, groundwater

• Saturation. Often dry

• Low to high energy

• Frequently PFO, PSS

Hydrology

RDS WL40’s and Ecotones

Headwater floodplains Slopes

Riparian depressions

1=PA2=NY – AD3=NY – Cat4=VA

1 2

3

4

4321

0

-10

-20

Region

Med

ian

of

Dep

th

Median depth (cm) – headwater floodplain

PA NY-A NY-C VA

(Kruskal Wallis H=5501.1, df=3, p<0.000)

1 2

3

4

4321

0

-10

-20

Region

Med

ian

of

Dep

th

Median depth (cm) – slope

PA NY-A NY-C VA

(Kruskal Wallis H=20425.21, df = 3,P< 0.001)

Median depth (cm) – riparian depression

PA NY-A NY-C VA

1 2

3

4

4321

0

-10

-20

Region

Med

ian

of

Dep

th

(Kruskal Wallis H=2688.20, df=3, p<0.001)

1 2

3

4

4321

0

-10

-20

Region

Med

ian

of

Dep

th

1 2

3

4

4321

0

-10

-20

Region

Med

ian

of

Dep

th

1 2

3

4

4321

0

-10

-20

Region

Med

ian

of

Dep

th

Headwater floodplain

Slope

Riparian depression

Wet and dry periods – by HGM subclass

And the reason is….

Credit: David Westphalen/Painet Inc.

• New York wetlands were substantially impacted by beaver

• Hard to find any site that was not modified by a beaver

• Really altered the duration of wet periods (though not dry periods)

• Reduced fluctuations

• We will need to revamp the HGM classification

• Works well south … other locations depend on beavers?