1. What is groundwater?
A mass of water store /flowing through pores and or cracks below the earth’s surface. It is widely distributed and renewable.
2. Why is groundwater important?
Groundwater represents the nation’s and the worlds principal reserve of fresh water and supplies on average 40% of the nations public water supply and all of the private water wells for a total of about half the fresh water Americans use. In VA 35% of the public water supply comes from groundwater and about 15% of residents are supplied with water from private gw wells. Nationally about 85 billion gallons of groundwater are pumped daily supplying drinking water, irrigation water, water for manufacturing and other uses.
3. Explain the relationship of groundwater to surface water.
Groundwater is a major contributor to the flow of streams and river and has a strong influence on rivers and wetland habitats. Areal recharge from precipitation percolates through the unsaturated zone to the water table and becomes groundwater where it is stored. Losses of water from streams and other water bodies of surface water such as lakes and wetlands can also recharge groundwater. The water goes both ways as groundwater can feed the streams, lakes and wetlands.
4. Briefly explain the hydraulic cycle?
The sun, causes surface water to evaporates as vapor into the air. Ice and snow can sublimate directly into water vapor. The vapor rises into the air where cooler temperatures cause it to condense into clouds. Air currents move clouds around the globe, cloud particles collide, grow, and fall out of the sky as precipitation. Some precipitation falls as snow and can accumulate as ice caps and glaciers, but most precipitation falls back into the oceans or onto land (where melts or falls as rain), where, due to gravity, the precipitation flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Much of the runnoff soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers (saturated subsurface rock), which store huge amounts of freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as ground-water discharge, and some ground water finds openings in the land surface and emerges as freshwater springs. Over time, though, all of this water keeps moving, some to reenter the ocean, and the cycle continues.
5. Groundwater may exist in underground rivers that run through caves and caverns. This may occur in eroded limestone area know as ___karst___ topography.
6. The Vadose zone is also knows as the _unsaturated_ zone.
7. The phreatic zone is also know as the ___saturated__ zone.
8. List the three main types of groundwater .
Confined, Unconfined and perched. The difference between a confined and unconfined aquifer is not clear in a fractured bedrock system. Unconfined aquifers are generally shallower because the water table is their upper boundary. Artesian aquifers are always confined.
9. If too much groundwater is pumper near the coast or if sea level rises, then saltwater intrusion__ would occur.
10.How is groundwater recharged?
Groundwater is recharged by precipitation infiltration. It can also be recharged by seepage from rivers and lakes in the upland areas.
11.What is the “fall zone” and why is it geologically important?
The fall zone is an imaginary north-south line that passes through Fairfax, Fredericksburg, Richmond, Petersburg and Empona. The fall zone or line crosses Virginia’s rivers at the points where they descend from the uplands. The fall zone is where the artesian aquifer recharges. The fall zone is the recharge area for the coastal artesian confined aquifer in VA.
12.What is the relationship of development to our groundwater resources?
Development usually involves increase in the amount of water withdrawls from the groundwater system. In addition, development covers more of the land space reducing recharge areas and increase density of impact from septic system and AOSS as well as application of pesticides and fertilizers. If a centralized waste treatment system us used the discharge location could impact the recharge and seawater infiltration as happened on Long Island.
13.Excessive pumping of groundwater in arid locations where the groundwater confining layer is compressible silt or clay this can result in ___subsidence_____ . A famous example of this effect is in the central valley of California.
Groundwater pumping can result in reduced river flows, lower lake levels, reduced discharges to wet lands and springs causing concerns about drinking water supplies, riparian areas and critical aquatic habitats.
14.What are the arguments to expand control of the groundwater in the tidewater costal plain?
Groundwater withdrawls have increased as population has increased. The artesian aquifer water level is declining. The recharge to the artesian layer may have been reduced. The lowering of pressure in the artesian layer is increasing saltwater intrusion.
15.List three sources of groundwater pollution and one likely contaminant from each source.
Underground storage tanks –gasoline or fuel oil.
Hazardous waste dumps, solvents and hazardous waste.
Landfills- contaminated leachate
Agriculture runoff containing pesticides or animal waste containing nitrates
Septic systems- bacteria, nitrogen, household chemicals
Mines acid runoff
16.The ability of water to travel through the rock or soil is known as __permeability (could also answer percolation or infiltration)___.
17.When a well is pumped faster than it is recharged then a ___cone of depression or drawdown_ occurs.
18.The level of water in a well that is not being affected by with drawl is the __static__ water level.
19.The water table is the ___top of the phreatic or saturated zone_____.
20.The downward flow of water through the pores or spaces of unsaturated rock or soil is called __percolation____.
21.All land and water with in a geologically defined drainage area is called the _groundwater system or basin_.
22.Should landowners have water rights? Why?
Yes. What value is the land without water? Or anything along those line. Public or non-local private ownership of water has resulted in vast diversions for both political and short sighted economic purposes. Problems faced have included allocations that exceed 100% of the supply, failure to maintain infrastructure for the water diversion system, destruction of natural habitats. Land without water rights has repeatedly become land without water and a desert wasteland as all natural occurring water is removed.
23.When you pump a groundwater well the groundwater system can respond in one or a combination of three ways. Name two.
Increased recharge or more water entering the system
Decreased discharge or less water leaving the system
Mining of the groundwater or removal of water that was stored in the system
24.List two aspects of a sustainable groundwater system:
Preservation of quality
Preservation of the aquatic environment
Integration of groundwater and surface water