Hydrogeologic unit

Figure 2.1 Generalized lithostratigraphic units and corresponding hydrogeological units of the Palo Duro Basin, USA (modified after Bassett and Bentley, 1982. Reprinted by permission of Elsevier Science Publishers BV).

Figure 2.23 Cross-sections showing the theoretical distribution of hydraulic head and gravity-induced groundwater flow pattern in two inhomogeneous drainage basins with laterally extensive hydrogeological units and a complex ground surface geometry (after Freeze and Witherspoon, 1967, Water Resources Researdi, Vol. 3, no. 2, Fig. 3, p. 628. Copyright by the American Geophysical Union).

Figure 2.29 Schematic illustration of free thermal convection in sloping parts of a hydrogeological unit with isothermal and impermeable boundaries (after Wood and Hewett, 1982. Reprinted with permission from Geochimica et Cosmochimica Acta, Vol. 46, Copyright 1982, Pergamon Press Ltd.).

The present hydrogeological framework of the sedimentary basin, which is characterized by the distribution, thickness and dip of porous and permeable hydrogeological units (aquifers/potential carrier-reservoir rocks, e.g. sands, sandstones, carbonates, fractured rocks) and poorly permeable hydrogeological units (aquitards/potential barrier rocks, e.g. shales, evaporites), and the location of geological structures and tectonic elements of importance for subsurface fluid flow, e.g. permeable or impermeable faults, unconformities... 

A regional picture of changes in groundwater pressure with depth and groundwater potential with depth in combination with potentiometric surfaces constructed for different hydrogeological units permit the delineation of the vertical and lateral extent of the shallow, intermediate and deep subsystems of burial-induced flow in the studied area. 

Figure 3. Cross-section showing major hydrogeologic units in the Fox River valley (see Fig. la for location of section A-A j. The regional recharge area for the St. Peter and deep sandstone aquifers occurs between the erosional edge of the Sinnipee and the regional ground water divide (denoted as "B " in figure). Modified from Batten and Bradbury (1996).

Fig. 3. Chemical character of spring water grouped according to four hydrogeologic units, Sao Paulo, Brazil,...

Mozley, P. Goodwin, L. (1995b) Patterns of cementation along the Sand Hill Fault, Albuquerque Basin, NM implications for paleoflow orientation and mechanisms of fault-related cementation. In Characterization of Hydrogeologic Units in the Northern Albuquerque Basin. (Eds Haneberg, W.C. Hawley, J.W.). New Mexico Bureau of Mines and Mineral Resources Open-File Report, 402-C, 3-11-3-23. 

The spatial distribution of aquifer structure was determined by an estimation of the depth of the bases of the hydrogeologic units from the digital topographic information and the classified thickness of the imsaturated and saturated zones (Fig. 8.1). 

In the areas of normal geothermal gradient and low coal ranks, SCs can only sparsely develop in fault zones in a complete hydrogeological unit. Under such conditions, water temperature, flow rate and PcOj are low. Karst can only develops in fractured zones where groundwater flow fast and the SCs are sparse. 

The key issue on division is how to determine the leakage level B and C. Taking the sandy-covered area as a hydrogeological unit, the sandy aquifer s... 

The hydrogeologic unit used for disposal must not discharge groimd water to the surface within the disposal site. 

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