Groundwater in surficial deposits
When the great ice sheets over Scandinavia retreated approximately 10 000 years ago, a lot of debris was deposited by the meltwater. These glacial rivers emptied into lakes or the ocean and left behind large deltas of sorted sand and gravel. Where tributaries met the main valley, sand and gravel fans were formed.
In these well-sorted sediments pore volume is often so large that filter wells can pump out a great deal of groundwater. Due to the continental uplift after the last ice age, sand and gravel deposits were often flooded by fresh water from streams. Theses deposits serve as a filter to produce high quality, clean water. Filter wells located in rivers and glacial stream deposits supply fresh water to many larger towns and villages such as Alta, Elverum, Kongsberg, Kongsvinger, Lillehammer, Røros and Voss.
Groundwater maintains a temperature that corresponds to the air's average temperature over the year. In earlier times, spring outlets were used as cold storage for milk and other fresh produce on farms and settlements. Spring water temperatures are evenly cold throughout the summer and will never freeze in winter. Hence, groundwater is today increasingly utilized for the heating and cooling of office and industrial buildings, when there are optimal geological conditions. Melhus (Sør-Trøndelag) and Elverum (Hedmark) are examples of places where groundwater in sediments is mainly used for heating and cooling.
Steady flow of water
During heavy frosts and longer periods of snowfall, it is groundwater that ensures the minimum daily stream flow. The steady flow of water ensures watercourses not to freeze, to the benefit of fish and other aquatic organisms. During long periods of drought, groundwater is available to vegetation, in both the fields and forests.
According to the Water Resource Act, all boring for water and hydrogeological investigation must be reported to NGU's well database. The information is presented on maps and as fact sheets in the National Groundwater Database (GRANADA). NGU collects and compiles data on groundwater wells and groundwater surveys, thus increasing the knowledge about the location and characteristics of groundwater in sedimentary deposits.