Environmental Engineering Reference
In-Depth Information
through wells. Not included is seepage of sewage or deep well injection of wastes (Aiken
and Kuniansky 2002).
Many states practice artificial recharge techniques to replenish groundwater reserves for
potable purposes when other sources of potable are either not available or too expensive.
Florida, New York, and California are examples (Aiken and Kuniansky 2002), and other
states in the high plains region of the United States including Kansas, Nebraska, Colorado,
South Dakota, and North Dakota are also using artificial recharge techniques.
The artificial recharge technique most commonly employed in a spreading basin .
Here, water is spread over a large surface area composed of permeable sediments such
as sand and gravel and permitted to seep into the ground and migrate to the aquifer
below.
Artificial recharge of groundwater offers several advantages:
• Limits loss of water through evaporation.
• Lower cost than dam construction or construction of water towers.
• Can store very large quantities of water.
• Lessons impact of subsidence.
• Permits the conjunctive use of groundwater and surface water. During wet peri-
ods, groundwater is stored for later use during dry weather and reduces the stress
placed on surface water reservoirs for supply.
The disadvantages for artificial recharge include
• Ineffective recovery leading to water loss
• Storing water beneath urban areas may lead to degraded groundwater quality and
pollution
• May increase dissolution if chemistry of infiltrating water is significantly different
than native groundwater chemistry
• Changes natural groundwater flow paths and directions
Some countries, especially those in more arid regions, are evaluating and experimenting
with techniques of artificial recharge using stormwater and reclaimed water (Dillon et al.
2007; Howard et al. 2007; Limaye 2007). These techniques may become commonplace in
the future as our climate changes and population increases generate a greater need for
freshwater. Urban areas where large populations use large quantities of water can improve
groundwater recharge through an understanding of the hydrogeological environment.
This understanding can help avoid aquifer contamination and groundwater mounding
(Howard et al. 2007).
3.7.2.4  Land Subsidence
Land subsidence is defined as the gradual settling or sudden sinking of the Earth's surface
caused by the movement of subsurface materials (Galloway et al. 2001). Subsidence is a
global issue. In the United States, more than 49,030 km 2 (17,000 mi 2 ) of land surface in 45
States has experienced some form of land subsidence. This is equivalent to a land area the
size of Vermont and New Hampshire combined.
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