Faults Controlling Groundwater Flow

Faults cause discontinuities in rock sequences and thus control groundwater flow. A fault may set high-conducting aquifer rocks against impervious rocks, resulting in water ascent along the fault zone and formation of springs marking the fault line (Fig. 3.8). Occasionally groundwater continues in its general flow path across a fault, but in different rock beds (Fig. 3.9). Another fault controlled example is the gathering of groundwater into rock beds of a rift valley (Fig. 3.10).

The above examples look simple, but in reality subterranean structures are often hard to recognize, and physical, chemical, and isotopic tracers are recruited to assist interpretation.

Fault zones may be open and highly conductive, or they may be sealed by mineral precipitation, forming hydraulic barriers.

Fig. 3.8 A fault has placed a high conducting aquifer against an igneous rock of §

low permeability. Water ascends along the fault zone, forming a line of springs. Only ^

part of the faults are open and conduct groundwater flow; others are clogged by J compression and/or mineralization.

Fig. 3.8 A fault has placed a high conducting aquifer against an igneous rock of §

low permeability. Water ascends along the fault zone, forming a line of springs. Only ^

part of the faults are open and conduct groundwater flow; others are clogged by J compression and/or mineralization.

Fig. 3.9 Groundwater changing aquifer beds along the flow path due to strata displacement by a fault.
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