Environmental Engineering Reference
In-Depth Information
3.8.3
Evaporites - checklist of questions
- Cavities, air-filled or water-filled?
- Cavities, soil-filled?
- Collapse of cavities - subsidence?
-Ground weakening due to ongoing solution?
- Increasing permeability due to ongoing solution?
- Heave due to growth of gypsum crystals?
- Large scale heave due to hydration of anhydrite?
- Chemical composition of groundwaters/reservoir waters?
-Presence of halite - chemical tests?
- Possibility of cementation of filter materials, by gypsum?
3.9
ALLUVIAL SOILS
For the purposes of this discussion “alluvial soils” includes soils which have been
deposited in the channels and flood-plains of rivers and in lakes, estuaries and deltas.
These soils are characterised by great variability, both vertically and laterally and can
range from clays of high plasticity through to coarse sands, gravels and boulders.
Detailed sedimentological studies in recent years have provided one or more “facies mod-
els” for the sediments (soils) deposited in each of the above environments. A facies model
includes block diagrams which summarise the compositions and configuration of the bodies
of soil deposited in a particular environment, together with an indication of the processes by
which they were formed. Figure 3.37 is a block diagram showing key features of the “mean-
dering river” model, which will be the only one discussed in detail here. Further information
about meandering rivers and details of the deposits formed in other environments can be
found in Leopold et al. (1964), Leeder (1982), Selley (1982), Lewis (1984) and Walker (1984).
Figure 3.37.
Schematic view of soils deposited by a meandering river (based partly on Figure 1 of
Walker, 1984).
 
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