Fig. 2.9. Anamalous expansion of water and its implications on survival of aquatic creatures in the ponds

The influence of pressure on the density is not significant as the water is relatively incompressible. Other than the external state variables, the density of water also varies with the degree of saturation of the soil. As the water content approaches residual conditions, where the degree of saturation is very low, the physico-chemical factors of the clay surface play an important role on the density of water as the water present in the form of adsorbed layer around the clay particles as shown in the Fig. 2.10.

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....................................Fig. 2.10. Adsorbed and free water in the soil matrix