WorldWide Drilling Resource

47 WorldWide Drilling Resource ® APRIL 2019 Open the Doorway to all the Event Photos during Minnesota Water Well Association 2019. To see all the photos from this event, go to www.worldwidedrillingresource.com or click here. Feel free to download at will and print the photo(s) of your choice. Compliments of WorldWide Drilling Resource ® . Photos are copyrighted and released for personal use only - no commercial use permitted. What is Groundwater? Adapted from Information by the U.S. Geological Survey Groundwater is a vital natural resource. According to the USGS (U.S. Geological Survey), groundwater is used by more than half of people in the U.S. for drinking and other household uses, and by about 75% of cities, but the largest use of ground- water is for irrigating crops. When rain falls to the ground, some of it remains on the surface in streams and lakes and is called surface water. When water seeps into the ground, some of it sticks to particles of soil and to the roots of plants. Water not used by the plants, con- tinues to move deeper into the ground through empty spaces and cracks in the soil, sand, or rocks until it reaches a layer of rock it cannot move through. The water then fills the empty spaces and cracks above that layer. The top of the water in the soil, sand, or rocks is called the water table and the water which fills the empty spaces and cracks is called groundwater. Surface water which seeps down to groundwater levels is called recharge water. Groundwater can be recharged through rain and snowmelt, or from water leaking through the bottom of lakes and rivers. It can also be recharged when water supply systems (pipelines and canals) leak or when crops are irrigated with more water than plants can use. The amount of groundwater flowing through the soil or rock depends on the size of the spaces in the soil or rock and how well the spaces are connected. The amount of spaces is referred to as porosity; permeability measures how well the spaces are connected. Beneath the water table, in the area where water can move easily through soil and rock, is the aquifer. Aquifers typically consist of gravel, sand, sandstone, or fractured rock such as limestone. These materials are permeable because they have large con- nected spaces which allows water to flow through. The spaces in a gravel aquifer are referred to as pores; the spaces in a fractured rock aquifer are called fractures. If a ma- terial contains pores which are not connected, groundwater cannot move from one space to another. These materials are said to be impermeable. Materials such as clay or shale have many small pores, but the pores are not well connected, restricting the flow of groundwater. Whether it is pumped from a well or it comes to the surface naturally as springs, when water leaves the aquifer it’s called discharge water. If more water is discharged than recharged, the water table can fall and wells may go dry. This commonly happens during periods of dry weather when recharge to the aquifers decreases. Groundwater can become unusable if it becomes polluted. If the material above the aquifer is permeable, pollutants can seep into groundwater. Common instances in- clude seepage of landfills, leaking septic tanks, and underground fuel tanks, as well as contamination from fertilizers or pesti- cides used on farms. Protecting groundwater from contamination and using water wisely will ensure groundwater’s continued role as one of our most valuable resources. This well, in southern Georgia, is tapped into an artesian aquifer, in which the water saturating the aquifer is under pressure from being confined between two fairly imperme- able layers of rock (above and below). Just like the air in a balloon rushing out, when a well taps an artesian aquifer, the water is pushed up the well pipe. USGS photo. WTR