The ongoing thread in this volume of Physics of Lakes is the presentation of different methods
of investigation for processes taking place in real lakes with a view to understanding lakes as
components of the geophysical environment. It is divided into three parts. Part I is devoted to
numerical modeling techniques and demonstrates that (i) wind-induced currents in
depth-integrated models can only adequately predict current fields for extremely shallow lakes
and (ii) that classical multi-layered simulation models can only adequately reproduce current
and temperature distributions when the lake is directly subjected to wind but not the
post-wind oscillating response. This makes shock capturing discretization techniques and
Mellor-Yamada turbulence closure schemes necessary as well as extremely high grid resolution
to reduce the excessive numerical diffusion. Part II is devoted to the presentation of
principles of observation and laboratory experimental procedures. It details the principles of
operation for current temperature conductivity and other sensors applied in the field. It
also discusses the advantages and limitations of common measuring methods like registration
from stationary or drifting buoys sounding and profiling from a boat etc. Questions of data
accuracy quality and reliability are also addressed. The use of laboratory experiments on a
rotating platform is based on an exposition of dimensional analysis and model theory and
illustrated using Lake Constance as an example. Part III gives an account of the dynamics of
lake water as a particle-laden fluid which coupled with the transport of the bottom sediments
leads to morphodynamic changes of the bathymetry in estuarine and possibly whole lake regions.
An elegant spatially one-dimensional theory makes it possible to derive analytic solutions of
deltaic formations which are corroborated by laboratory experiments. A full three-dimensional
description of the evolution of the alluvial bathymetry under prescribed tributary sediment
input indicates a potential subject for future research.
