PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
April 2014
323
Mapping the Subaqueous Soils of Lake
Champlain’s Missisquoi Bay Using Ground-
Penetrating Radar, Digital Soil Mapping and
Field Measurements
Zamir Libohova, James Doolittle, Reed Sims, Thomas Villars, and Larry T. West
Abstract
Eutrophication associated with high concentrations of
phosphorus in Missisquoi Bay has raised concerns about
its influence on submersed aquatic vegetation. Subaqueous
soils could play an important role in nutrient cycling, al-
gae blooms, the spread of invasive aquatic vegetation, and
water quality. The objectives of this study were to (a) char-
acterize some of the morphological, physical and chemical
properties of subaqueous soils in Missisquoi Bay based on
ground-penetrating radar and soil analysis; and (b) assess
relationships among the subaqueous soil landscapes, radar
facies, and submersed aquatic vegetation. Coarse Strati-
fied Sediments and Lacustrine Silt radar facies associated
with Delta/Nearshore and Lakebed/Bay Bottom subaqueous
soil-landscape units covered 90 percent of the study area.
The Lacustrine Silt radar facies occurred in relatively deep,
low-energy, depositional areas and had the highest P con-
centrations. The majority of the submersed aquatic vege-
tation was associated with Delta/Nearshore and Fringing
Peatland subaqueous soil landscapes under shallow water.
Introduction
The large watershed, extensive shoreline, and numerous
shallow bays of Lake Champlain make it exceptionally vul-
nerable to detrimental effects associated with land-use change
and wastewater effluents (Facey
et al
., 2012). Urban growth
and changes in land management are factors cited for the
increased eutrophication and sedimentation of Lake Cham-
plain and its numerous bays (Poirier
et al
., 2012). The area
surrounding Missisquoi Bay, a shallow (<5.0 m), eutrophic
bay of Lake Champlain, has witnessed a significant expansion
in the acreage devoted to row crops (principally corn and soy-
bean) and a reduction in the acreage devoted to forage crops
and pasture (Facey
et al
., 2012; Missisquoi Bay Inter-Agency
Advisory Committee - Montérégie, 2004). Row crops require
large quantities of fertilizers, herbicides and pesticides, and
lead to higher soil erosion rates than forage crops and pasture.
Missisquoi Bay has the highest reported levels of phospho-
rus measured in Lake Champlain. The increased phosphorus
loading into Missisquoi Bay has been associated with eutro-
phication and episodic proliferations of dense blue-green
algae blooms (cyanobacteria) (Missisquoi Bay Inter-Agency
Advisory Committee - Montérégie, 2004).
Knowledge of the near-shore, submersed soil landscapes
of Lake Champlain and its bays can be extremely useful in
addressing nutrient management, sedimentation, and water
quality issues. The recognition of subaqueous soils and their
importance for submersed aquatic vegetation (
SAV
) and other
ecological functions has led to efforts in distinguishing them
from geologic concepts traditionally used for their character-
ization. Soil Taxonomy (Soil Survey Staff, 2010) recognizes
subaqueous soils within Entisols and Histosols orders in the
Wassents and Wassists suborders. They are defined as soils
that have “positive water potential at the soil surface for more
than 21 hours of each day in all years.” Like upland “subaeri-
al” soils, subaqueous soils can be classified to the series level
in Soil Taxonomy. Each subaqueous soil series has a distinct
range in physiochemical properties, and also like upland
soils, can have specific relationships to landscape position,
slope gradient, temperature, and other soil-forming factors
(Demas and Rabenhorst, 2001). Estuarine and fresh water
restoration efforts and initiatives (Hartley, 2007) have created
a demand for more detailed and spatially explicit representa-
tion of subaqueous soils distribution, depth and physical and
chemical properties.
Distinct relationships are known to exist among subaque-
ous soils, aquatic vegetation, habitats, sediments, and land-
scapes (Bradley and Stolt, 2003; Demas and Rabenhorst, 1999
and 2001; Osher and Flannagan, 2007). These relationships
have fostered the recognition of distinct subaqueous soil land-
scape units. Subaqueous soil landscape units are identified
on the basis of bathymetry, slope gradient, landscape shape,
sediment type, and geographical location (Bradley and Stolt,
2003). Bradley and Stolt (2003) and Demas and Rabenhorst
(1999 and 2001), argue that subaqueous landscapes are simi-
Zamir Libohova is with the USDA-NRCS-National Soil Survey
Center, 100 Centennial Mall North, Federal Building, Room
152, Lincoln, NE 68508 (
).
James Doolittle is with the USDA-NRCS-National Soil Survey
Center, 11 Campus Blvd., Suite 200, Newtown Square, PA
19073.
Reed Sims is with the USDA-NRCS, 356 Mountain View
Drive, Suite 105, Colchester, VT 05446.
Thomas Villars is with the USDA-NRCS, 28 Farmvu Drive,
White River Junction, VT 05001.
Larry T. West is retired and working as a private consultant.
Photogrammetric Engineering & Remote Sensing
Vol. 80, No. 4, April 2014, pp. 323–332.
0099-1112/14/8004–323
© 2014 American Society for Photogrammetry
and Remote Sensing
doi: 10.14358/PERS.80.4.323
