Porosity and grain size relationship

porosity and grain size relationship

Relationships between porosity, median size, and sorting coefficients of synthetic sands. John J. W. Rogers. John J. W. Rogers. Rice University, Houston, TX. They are equal! PARTICLE SIZE ALONE DOES NOT AFFECT. Porosity As pore size increases, permeability increases. • Direct relationship. Pore Size. Perm. Often, when we think of something that is solid we think about rocks. But in reality, rocks have tiny holes of air inside them. This is called porosity. In this science.

Put the size of the rocks on the x-axis the horizontal axis going across the bottom and the amount of empty space on the y-axis the vertical axis going up and down. Which particle size had the most amount of empty space? The least amount of space? Was there a pattern to your data? Does this reveal any relationship between particles size and pore space?

If you like this project, you might enjoy exploring these related careers: Geoscientist Just as a doctor uses tools and techniques, like X-rays and stethoscopes, to look inside the human body, geoscientists explore deep inside a much bigger patient—planet Earth.

Geoscientists seek to better understand our planet, and to discover natural resources, like water, minerals, and petroleum oil, which are used in everything from shoes, fabrics, roads, roofs, and lotions to fertilizers, food packaging, ink, and CD's. The work of geoscientists affects everyone and everything. Read more Variations Here you used differently sized pieces of the same material, crushed granite. What about other materials and minerals? Try comparing different types of crushed rock like volcanic rock, gravel, quartz, sandstone, or limestone.

Soil is a mixture of rocks, minerals and organic matter.

Porosity and Particle Size | Science Project

Porosity is also a property of soil. Try the same experiment using different types of soil: The only thing to do differently is place a screen on top of the cup to keep organic matter from floating out as you pour the water into the cup. Do different types of soils have different porosities? You can calculate the porosity of each of the cups of differently-sized rocks you used in this experiment.

The same thing happens beneath the surface of the Earth, where pressure is higher beneath the hills and lower beneath the valleys The Earth's surface can be divided into areas where some of the water falling on the surface seeps into the saturated zone and other areas where water flows out of the saturated zone onto the surface.

Areas where water enters the saturated zone are called recharge areas, because the saturated zone is recharged with groundwater beneath these areas. Generally, recharge areas are greater than discharge areas.

Groundwater movement is slow relative to that in surface streams. This is because it must percolate through pore openings and is further slowed by friction and electrostatic forces. For comparison, typical rates of flow are as follows: Local — Shallow flow occurs over short times and distances, whereas, deep long distance flow occurs over time scales of centuries. The rate at which groundwater moves through the saturated zone depends on the permeability of the rock and the hydraulic head.

The hydraulic head is defined as the difference in elevation between two points on the water table. The hydraulic gradient is the hydraulic head divided by the distance between two points on the water table.

The velocity, V, is of groundwater flow is given by: If we multiply this expression by the area, A, through which the water is moving, then we get the discharge, Q. It simply states that discharge is proportional to the hydraulic gradient times the permeability. Note that like stream discharge, Q has units of volume per time i.

Springs A spring is an area on the surface of the Earth where the water table intersects the surface and water flows out of the ground.

porosity and grain size relationship

Some springs occur when an aquitard intersects an aquifer at the surface of the Earth. Such juxtaposition between permeable and impermeable rock can occur along geological contacts and fault zones see figure The waters are usually rich in dissolved minerals that often precipitate around the springs. They develop in two settings: Hot springs are distinctive geological features.

If the surface through volcanic ash they become a viscous slurry called mudpots. If they precipitate dissolved minerals on cooling, they can form deposits like travertine made of calcite.

Hot springs can also produce a wide range of colors due to thermal sensitive bacteria that metabolize sulfur minerals.

Geysers form when hot water erupts to the surface. They are caused by boiling of the water at depth which causes vapor bubbles to rise and reduce the pressure. This results in rapid boiling which sends the water to the surface as a geyser.

Soil Structure, Density and Porosity for Agricultural Field Officer (Hindi/English)

The cycle then repeats after the empty chamber is refilled with water and is heated to the boiling temperature. Hot springs and geysers are common in active volcanic regions, notably Yellowstone Park in Wyoming.

Wells A well is human-made hole that is dug or drilled deep enough to intersect the water table. Wells are usually used as a source for groundwater. If the well is dug beneath the water table, water will fill the open space to the level of the water table, and can be drawn out by a bucket or by pumping. Fracture systems and perched water bodies can often make it difficult to locate the best site for a well.

porosity and grain size relationship

A special kind of confined aquifer is an artesian system, shown below. In an artesian system, the aquifer is confined between aquitards and is included so that the pressure inside the aquifer can push the water from a well or spring upward to nearly the same level as the top of the water table. Artesian systems are desirable because they result in free flowing artesian springs and artesian wells. Changes in the Groundwater System When discharge of groundwater exceeds recharge of the system, several adverse effects can occur.

Most common is lowering of the water table, resulting in springs drying up and wells having to be dug to deeper levels. If water is pumped out of an aquifer, pore pressure can be reduced in the aquifer that could result in compaction of the now dry aquifer and result in land subsidence. In some cases withdrawal of groundwater exceeds recharge by natural processes, and thus groundwater should be considered a non-renewable natural resource.

Water Quality and Groundwater Contamination Water quality refers to such things as the temperature of the water, the amount of dissolved solids, and lack of toxic and biological pollutants. Water that contains a high amount of dissolved material through the action of chemical weathering can have a bitter taste, and is commonly referred to as hard water. Hot water can occur if water comes from a deep source or encounters a cooling magma body on its traverse through the groundwater system.

Such hot water may desirable for bath houses or geothermal energy, but is not usually desirable for human consumption or agricultural purposes.

Most pollution of groundwater is the result of biological activity, much of it human. Among the sources of contamination are: Sewers and septic tanks Waste dumps both industrial and residential Gasoline Tanks like occur beneath all service stations Biological waste products - Biological contaminants can be removed from the groundwater by natural processes if the aquifer has interconnections between pores that are smaller than the microbes.

For example a sandy aquifer may act as a filter for biological contaminants. Agricultural pollutants such as fertilizers and pesticides. Salt water contamination - results from excessive discharge of fresh groundwater in coastal areas. Groundwater contamination can result from a point source where the contaminant plume emanates from 1 spot. Concentrations of the contaminant are highest near the source and decrease away from the source. Or, from a widespread source where the pollution is introduced over a wide area and diffused throughout the groundwater over a broad region.

Nonpoint source contaminants are difficult to identify and address. Groundwater contaminant plumes change over time. They grow in length with groundwater flow. They grow in width by diffusion and dispersion. Large plumes pollute large areas and affect many people.

porosity and grain size relationship

Remediation of Groundwater Contamination Problems In order to begin remediationcontaminant characterization is first done. Monitoring wells are installed to assess flow behavior. This allows for chemical testing to quantify the amount of and character of the contaminants.

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Strategies are then designed to reduce health risks. Remediation is usually quite expensive. Most strategies include removing the source of the contaminant, then pumping the groundwater out and treating it. Sometimes heat is pumped in to volatilize the groundwater or steam is pumped in to clean out the containments. Newly developed techniques uses bacteria to clean the groundwater in a process called bioremediation. Prevention of Groundwater Contamination Contamination is best prevented by managing land uses.

Landfills now require lining the bottom of the landfill with impermeable clay and plastic liners.

porosity and grain size relationship

Underground storage tanks require double-lining to prevent leakage. Still the best practice is to require that contaminants not be allowed into the groundwater system. Dissolution - Recall that water is the main agent of chemical weathering. Groundwater is an active weathering agent and can leach ions from rock, and, in the case of carbonate rocks like limestone, can completely dissolve the rock.

Chemical Cementation and Replacement - Water is also the main agent acting during diagenesis.