Ground water

Rainfall is absorbed (infiltrates) farmland soil

Because of urbanization, the rainfall cannot infiltrate, so it’s runoff,

Where does the water go???

Frequent large storms can exceed the system's ability to handle the load. This can cause mixing of sanitary and storm sewer water that results in flooding an water back-up

If the sewer system is full or it can’t handle the rate of water flow, the rainwater has no where to go but back (up) into your household drains.

The Deep Tunnel Project

Begun in 1975, and at one time the nation's largest municipal water pollution control project It involves the construction of 109 miles (174 kilometers) of tunnels 9 to 33 feet (3 to 10 meters) in diameter. Excavated in limestone bedrock as much as 350 feet (107 meters) below the surface.

These tunnels will collect any combined sanitary and storm sewer flows and send them to reservoirs for storage…

…until the area's water reclamation plants can treat and safely discharge the water. The Deep Tunnel is designed to reduce and nearly eliminate the release of untreated water to streams, Lake Michigan, and people's basements.

Groundwater

Groundwater is the most abundant available source of fresh water Rivers, lakes, streams = 1.4% of fresh water

Pore spaces are filled mainly with air Zone of aeration Unsaturated zone Pore spaces are filled mainly with air Zone of saturation All pore spaces in the material are filled with water Water within the pores is groundwater Water table – the top of the zone of saturation

Groundwater Precipitation (rain water) that enter (infiltrates) the ground. And is STORED in the ground in the spaces between rock particles in aquifers. (Groundwater is the most abundant available source of fresh water) Factors that affect the amount of water that infiltrates the ground: type of rock or soil climate topography vegetation land use soaks-in

Soil and vegetation allow water to slowly infiltrate Urban streets, concrete, asphalt roads and buildings do not allow water to infiltrate and the water quickly runs-off

What determines if precipitation will INFILTRATE or RUN-OFF? Figure 5.3 What determines if precipitation will INFILTRATE or RUN-OFF?

Porosity amount of pore spaces, voids, openings. Ground materials ability to HOLD water. Determines storage of groundwater. The percent % of the total volume of material that consists of pore spaces

What percent of the rock is pores spaces??

Porosity factors: 3-S’s Size of particles: (large, small, fine) Shape of particles (rounded or angular) Sorting of particles: - well-sorted: all the SAME size and shape - unsorted: mixed, DIFFERENT size and shape Compactness of particles Which is well-sorted? Compacted? Un-sorted?

Porosity Lab: Compare the porosity of materials   Material Total Volume of Material (dry) cm3 Volume of water In spaces % of spaces in total volume Rank #1 - #4 (1 is highest porosity) Marbles Glass BB’s Pebbles Aquarium gravel Fine sand

Post-lab questions: 1.Which material that had highest porosity: ___________________ Which material that had lowest porosity: ___________________ 2.Which of your materials was a well-sorted material: _______________ Which of your materials was an unsorted material: ________________

Post-lab graphs 1. Sketch a graph that shows the relationship between porosity and particle size porosity Particle size 2. Sketch a graph showing the relationship between porosity and sorted Unsorted well-sorted 3. Sketch a graph showing the relationship between porosity and shape. (round vs. angular)

sa Rank the following as #1 for the highest porosity and #5 as the lowest porosity. And describe factors sand Clay soil Good porosity Due to: Round shape Same size well-sorted High porosity Due to: Same big size Same shape Well-sorted High porosity Due to: Big size But.. unsorted and angular Good porosity. Due to: Same size Well-sorted LOW porosity Due to: unsorted Small clay particles fill-in the pore spaces between the large particles.

What is the POROSITY of the rock? __________% 20 ml of water filled the spaces What is the POROSITY of the rock? __________% 50 cm3 of dry rock