PHYSICAL MATHEMATICS SEMINAR

TOPIC:		CHARACTERIZING THE DYNAMICAL REGIMES OF A LAKE

SPEAKER:	JORG IMBERGER
		Centre for Water Research
		University of Western Australia

ABSTRACT:

The understanding of lake hydrodynamics has made much progress in
the last twenty years and a broad, holistic overview now exists.  However,
it is still difficult for the general limnological and hydraulic
practitioner to gain a quantitative description of the hydrodynamical
regimes active in a particular lake at a particular time.  Such an
overview is important because the mixing and transport processes operating
in a lake determine, to a large degree, the ecological response of the
lake to meteorological forcing, inflows and outflows.

In the field of hydraulics a well established methodology exists, based on
the Reynolds and Froude numbers, which allows characterization of flows
into laminar or turbulent and super or sub-critical.  Once classified in
this way, many attributes of the flow immediately follow.  In this talk I
attempt to provide an analogous first order methodology that will allow
the practitioner to classify the hydrodynamic regimes operating in a lake.
Such a classification scheme should allow the limnologist to put his or
her ecological data into an appropriate physical context.  I define eight
non-dimensional numbers and illustrate the dynamical regimes quantified by
their magnitude.  These are surface layer stratification patterns,
metalimnetic upwelling, hypolimnetic upwelling, mixing in the lake's
interior and the benthic boundary layer, the influence of the earth's
rotation, exchange of littoral water, occurrence of high frequency
internal waves, resuspension of bottom sediments, inflow characteristics
and outflow selectivity.

DATE:		TUESDAY, DECEMBER 4, 2001

TIME:		2:30 PM

LOCATION:	Building 2, Room 338

Refreshments will be served at 3:30 PM in Room 2-349


Massachusetts Institute of Technology
Department of Mathematics
Cambridge, MA  02139