Groundwater

Hydrologic cycle relation

Infiltration is the SLOWEST part, but leads to groundwater

Surface water relationship

Streams receive water from runoff and groundwater, why river levels remain high long after heavy rain

Flow behaviour

Water flows slowly in a downslope and predictable pattern; useful to predict pollutant flow

Amount of Water Available

Most freshwater in glacial ice, agriculture irrigation bigggest use, groundwater aquifers have readily available water

Groundwater withdrawal and consequence

If outgoing water exceed recharge, there is a drawdown in water and a cone of depression forms

Water overdraft

Agricultural demand, where output is greater than input, causing compaction, permanently lowering permeabilty, and subsidence (land sinking)

Salt Water Incursion

Inflow of salt in coastal areas, wells may start pumping saltwater as a result `

Unconfined aquifers

Receiving water firectly from land surface above

Confined aquifers

Overlain by layer of kinda impermeable material to limit water movement, an AQUITARD is the impermeable unit of material

Artesian systems

Able to “pump themselves” when below the pressure surface because the recharge area is high, then “hydraulic head” is created that allows water to flow (water essentially wants to rise toward the pressure surface)

Septic tank sewage disposal

Contaminated water infiltrates soil, and organic contaminants are usually naturally broken down by bacteria, but when the soil si too permeable, the groundwater moves to quick for purification; best to avoid excessive pumping to decrease permeability

Karsts

Features produced by groundwater, dissolution of CO3 produces topography features

Caves/caverns

Acidic rain percolates through soil into limestone fractures, continues until caves are formed, caves formed when water table drops

Dripstone

Calcite from dripping CO3 saturated water, Stalactites hang down, stalagmites hang up, and columns are connected pillars

Sinkholes

When “roofs” of caves collapse,a nd common in temperate-tropical regions underlain by CO3

Tower karst

Extreme development causes pillars of limestone between areas of cave collapse