I am interested in learning about practical methods to reduce the effect
of local katabatic flow of air in making low lying areas cooler and more
susceptible to frost. There are many references that cold air can be
trapped in low lying areas and that landforms, hedges, windbreaks,
embankments etc can affect the flow of cold air and hence the frost
effect.

Most advice seems to be along the lines of "don't plant frost tender
crops in hollows" or "plant in hollows later in the spring". Well if
you
have a property that has low areas there is no point in wishing it
wasn't that way - you need to make the best of what you have.

Can anybody give me a reference to practical advice on how to use
hedges,
windbreaks etc to reduce the effect, by directing the cold flow away
from the garden or crop?

Specificaly I am interested in how to diagnose the situation, to be able
to
find out to what extent cold air flow is affecting frost intensity on my
property and secondly, if this is happening, how to go about reducing
the problem where possible.

David