Phreatic water

The complexity of phenomena controlling the chemical composition of waters. In the soil layers, this composition would depend principally on biological and biochemical processes, in relation to the activity of organisms but at the level of phreatic waters the chemical composition would rather be controlled by physicochemical conditions (solution-mineral equilibria). 

A preliminary analysis of the results of the individual samples shows their relative homogeneity all titrated waters, including seepage (drainage) and phreatic waters, have low solute concentrations, generally between 0.2 and 4 meq./l and high resistivities, between 5 10 and 10 12 cm. 

The MPV-values of the major ions expressed in mg/1 are low, similar to those which have been obtained in springs and phreatic waters of the crystalline area, with a humid, temperate, or tropical, climate (Tardy, 1969 Bourrife, 1978). 

Consequently, only a fraction of the chemical charge which comes into the soil, where it is concentrated by evapotranspiration, is carried down with drainage waters into the deep layers of soil and into phreatic waters. The retention of dissolved solids exists also in the deep layers of the soil (between 2 m depth and the water table), since the concentration of solution in spring waters is lower than in drainage waters, except for Si and Na, as above mentioned. 

Dissolution of carbonate grains may occur as a consequence of (i) a build up of Pqo, the vadose zone due to the extensive respiration of plants and micro-organisms (ii) an increase in the concentration of organic (humic-fulvic) acids due to secretion by, or decay of, plants and (iii) mixing between waters with chemically dilferent compositions, particularly in terms of Pco, (c-g- vadose and phreatic waters), which is referred to as mixing corrosion (Wigley Plummer, 1976). 

The permeability coefficient is 0.22-206.1 m/d and the specific capacity is about 0.0695-0.455 L/(s m). This aquifer receives the precipitation and Quaternary phreatic water with big seasonal change. Currently, the pumping is its discharge form. 

The structure of Shendong Mine Area is simple, and contains mainly Jurassic strata which with 185 m of average thickness. It has the characteristics of shallow buried depth, and thin bedrock, and thick loose sand and rich phreatic water. 

Underground water is mainly supplied by atmospheric precipitation, and classified three classes which are respectively the pore phreatic water of Cainozoic unconsolidated strata, the cranny phreatic water and pressure water of Mesozoic, the hole fissure phreatic water of burnt rock. 

Consequently, we may calculate the phreatic water s seepage time of aquifer-protective mining condition s each class according to the seepage speed of Table 4 by taking 45 MPa as the comprehensive strength of overlying strata, and see Table 5 and Table 6. 

The pores within the zone of saturation are filled with water, generally referred to as phreatic water. The upper surface of this zone is therefore known as the phreatic surface but is more commonly termed the water table. Above the zone of saturation is the zone of aeration... 

Zhiyang valley is divided into two underground water partitions. They are the Lishan fault block in the hilly and low mountain, and Loess Region. The major groundwater type is the fissure water in bedrock and phreatic water in Quaternary loose voids. 

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