geo lab 9

water table

boundary that separates the saturated zone from the unsaturated zone

aquifer

rock and sediment layers that have high porosity and permeability

hydraulic head

measurement of the potential energy of a fluid based on the pressure head and the elevation

so basically the height that water rises to in a well

potentiometric (or piezometric) surface

imaginary plane where water will equilibrate to if allowed to flow

what does the hydraulic head usually mirror?

overall topography because this is where the water table is located

what is mapping of a potentiometric (piezoelectric) surface important for?

aids in determining where groundwater flows easily and water direction it flows

various tests used to measure characteristics of groundwater

pH, temperature, turbidity, and mroe

what are pumping tests?

involve using a pump to withdraw water from a well that is then monitored from a nearby well to see how the groundwater table (hydraulic head) changes over time

what is hydraulic conductivity

measurement of how easily water flows through the aquifer (sediment, rock, or soil)

what is hydraulic conductivity based on?

porosity and permeability of the aquifer materials

what is the difference between saturated and unsaturated zones in the subsurface?

unsaturated zone lies above the water table and contains a mixture of air and water

saturated zone lies below the water table and all pore spaces are filled with water

what qualities do a good aquifer have?

high porosity (space to hold water)

high permeability (ability for water to flow through it)

how is a hydraulic head usually measured in the field?

water level meter or ta to find how high water stands in a well relative to a reference point like ground level

during a pumping test, why is it important to monitor water levels in a nearby well and not just the one being pumped?

helps us understand the aquifer’s response to pumping

also avoids confounding the data with turbulence or immediate water level changes happening in the pumped well

what factors could cause two wells in close proximity to show different groundwater characteristics like pH, temperature, or conductivity?

difference in proximity to contaminants,

depth,

aquifer material

what are some possible sources of contamination in groundwater?

agricultural runoff, industrial waste, leaky septic systems, landfills, nitrates, heavy metals, organic solvents

how does topography influence the direction and rate of groundwater flow?

groundwater generally flows from higher elevations to lower elevations

topography shapes water table

the flow often mirrors surface slopes, steeper slopes can drive faster flow rates