Puricare Industrial Enterprises: GROUNDWATER DEPLETION AND SALT WATER INTRUSION - One water-quality threat to fresh groundwater supplies is contamination from saltwater intrusion.

Sunday, December 25, 2016

GROUNDWATER DEPLETION AND SALT WATER INTRUSION - One water-quality threat to fresh groundwater supplies is contamination from saltwater intrusion.

Groundwater depletion, deterioration of water quality and saltwater intrusion

Groundwater depletion

Groundwater is a valuable resource throughout the world. Where surface water, such as lakes and rivers, are scarce or inaccessible, groundwater supplies many of the hydrologic needs of people everywhere.

In the United States, it is the source of drinking water for about half the total population and nearly all of the rural population. it provides over 50 billion gallons per day for agricultural needs.

Groundwater depletion, a term often defined as long-term water-level declines caused by sustained groundwater pumping, is a key issue associated with groundwater use.

Excessive pumping can overdraw the groundwater "bank account"

The water stored in the ground can be compared to money kept in a bank account. If you withdraw money at a faster rate than you deposit new money you will eventually start having account-supply problems.

Pumping water out of the ground faster than it is replenished over the long-term causes similar problems. The volume of groundwater in storage is decreasing in many areas as a result of over pumping.

Groundwater depletion is primarily caused by sustained groundwater pumping.

What are some effects of groundwater depletion?

Pumping groundwater at a faster rate than it can be recharged can have some negative effects of the environment and the people who make use of the water:

Some of the negative effects of groundwater depletion are:

· drying up of wells

· reduction of water in streams and lakes

· deterioration of water quality

· increased pumping costs

· land subsidence

Lowering of the water table

The most severe consequence of excessive groundwater pumping is that the water table, below which the ground is saturated with water, can be lowered. For water to be withdrawn from the ground, water must be pumped from a well that reaches below the water table.

If groundwater levels decline too far, then the well owner might have to deepen the well, drill a new well, or, at least, attempt to lower the pump. Also, as water levels decline, the rate of water the well can yield may decline.

Increased costs for the user

As the depth to water increases, the water must be lifted higher to reach the land surface. If pumps are used to lift the water (as opposed to artesian wells), more energy is required to drive the pump. Using the well can become prohibitively expensive.

Reduction of water in streams and lakes

There is more of an interaction between the water in lakes and rivers and groundwater than most people think. Some, and often a great deal, of the water flowing in rivers comes from seepage of groundwater into the streambed.

Groundwater contributes to streams in most physiographic and climatic settings. The proportion of stream water that comes from groundwater inflow varies according to a region's geography, geology, and climate.

Groundwater pumping can alter how water moves between an aquifer and a stream, lake, or wetland by either intercepting groundwater flow that discharges into the surface-water body under natural conditions, or by increasing the rate of water movement from the surface-water body into an aquifer.

A related effect of groundwater pumping is the lowering of groundwater levels below the depth that streamside or wetland vegetation needs to survive. The overall effect is a loss of riparian vegetation and wildlife habitat.

Land subsidence

The basic cause of land subsidence is a loss of support below ground.

In other words, sometimes when water is taken out of the soil, the soil collapses, compacts, and drops. This depends on a number of factors, such as the type of soil and rock below the surface.

Land subsidence is most often caused by human activities, mainly from the removal of subsurface water.

Deterioration of water quality - saltwater intrusion

One water-quality threat to fresh groundwater supplies is contamination from saltwater intrusion.

All of the water in the ground is not fresh water; much of the very deep groundwater and water below oceans is saline.

In fact, an estimated 3.1 million cubic miles (12.9 cubic kilometers) of saline groundwater exists compared to about 2.6 million cubic miles (10.5 million cubic kilometers) of fresh groundwater .

Under natural conditions the boundary between the freshwater and saltwater tends to be relatively stable, but pumping can cause saltwater to migrate inland and upward, resulting in saltwater contamination of the water supply.

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