Geoscience Reference
In-Depth Information
saturated by water, e.g., by Wilford R. Gardner and his doctorate students. Don
Kirkham concentrated another group around him, and he was the fi rst to develop the
solution of Richards' equation to defi ne boundary conditions by the infi nite series.
We have already mentioned his name earlier in Chap.
8
. Anyway, more about
practical applications will follow in the next chapter.
Conditions in fi eld soils at any location within the global landscape are compli-
cated owing to the fact that the soil temperature oscillates differently to various
depths during every day of the year within soil profi les having uneven soil water
contents as a result of regional and seasonal precipitation. The soil hydraulic char-
acteristics like contact angle and capillarity are dependent upon the temperature. A
similar type of infl uence exists in unsaturated hydraulic conductivity. Hence, we
must consider the impact of variable temperatures creating combined fl ows of both
heat and water within soil profi les. Similarly in warm arid climate, the soluble inor-
ganic salts accumulate in a salty soil horizon and they are transported and this trans-
port may infl uence the fl ow of water. Thus, we are in a similar situation as we
described for the Gulf Stream at the start of this chapter. The difference is in the
scale, while for Gulf Stream it was in hundreds of kilometers, and in soils the dis-
tances are in tens of centimeters. But the main principle still remains.
