Introduction to Groundwater Flashcards
Hydrogeology
The sub-discipline of geology dealing with the distribution and movement of water in the Earth’s crust
Common Applications of Hydrogeology
- Extraction of water: drinking, irrigation, manufacturing
- Dewatering: construction, quarrying, flooding
- Contamination: industrial discharge, spills, leaks from buried tanks, infiltration of agricultural runoff
- Assessment of extraction effects
- Quantification and management of groundwater resources
What are aquifers
- Saturated rock/soil layer/s forming a reservoir for groundwater
- contains pores or open spaces to hold water
- pores or spaces generally interconnected
Forms of aquifers
- Unconfined
- Confined
- Semi-Confined (Leaky)
- Perched
Unconfined Aquifer
the water table forms the upper boundary and is exposed so is free to rise and fall
Confined Aquifer
groundwater is isolated from the atmosphere by much less permeable layers (aquitards and/or aquicludes) and is subject to higher pressures than atmospheric pressure
Aquitard
layer «_space;permeable than aquifer, not impermeable
Aquiclude
an impermeable layer (aquifuge if water-free)
Semi-Confined Aquifer
intermediate between unconfined and confined
Perched
discontinuous (in space and time) saturated conditions overlie unsaturated conditions
2 Categories of aquifer properties
Storage and Flow properties
What are the storage properties and what do they dictate
- dictate how aquifers store and release water
- Porosity, specific storage, specific yield and storativity
What are the flow properties and what do they dictate
- dictate how water moves through aquifers
- hydraulic conductivity, intrinsic permeability, transmissivity
Porosity
- % of aquifer consisting of pore spaces (voids)
- Larger pore space (more voids) = greater porosity therefore aquifer has greater water bearing capacity
- provides indication of volume of water in aquifer
Permeability
capacity of aquifer to transmit water through pore space and is related to connectivity of pores