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Groundwater and surface watercourses

The existence of water resources depends on many factors such as:

• The penetration and movement of underground waters
• The return of water to the surface
• Surface water flow

The infiltration of water depends on the characteristics of the rocks in the subsurface. They may be permeable or raincoat confection:
Permeable Rocks are porous and generally igneous or sedimentary origin and mainly of limestone with numerous fractures. A rocky body aquifer is defined if is sufficiently permeable to cross the waters but able to keep them in a meaningful way to feed springs and wells.
Waterproof: Rocks are usually clay or marl. A rocky body calls acquicludo if it can hinder or prevent afflux and groundwater flow.
The joint intervention and presence of permeable and impermeable rocks gives rise to aquifers: structures where water accumulates. The strata are defined tables when the upper limit of the water is free to fluctuate depending on the amount of water it receives. If surface water penetrate deep and gather in an aquifer between two acquicludo, it forms a flap imprisoned. In this particular type of ground water is subjected to a pressure that depends on their height difference compared to the surface of the water. You can get artesian wells.

The waters that have infiltrated emerge on the surface with the sources. The waters that may arise, depending on the rocks crossed, can be:
Drinking water: having a salinity of between 10 and 50 centigrams per litre
Mineral Waters: essentially with salt content increased
Thermal waters: with temperatures of between 20 and 100 degrees Celsius
Thermo-mineral Waters: hot and considerably rich in salts.

The sources can be of various types:
Sources of runoff: when one waterproof layer tilted surfaces along one side of a Valley and it does drain the water
Barrier Sources: when a side obstacle or a fault do accumulate, along an inclined plane, a quantity of water that would tap on the surface
Overflow Sources: when water gushes from a concave bed that
collects more water than they can hold
Karst Springs: when leaving overflowing waters that have penetrated into a relief through the innumerable cavities present in a limestone rock.

A considerable part of precipitation water returns to the sea through rivers. The portion of land that contributes its water to feed a watercourse is the river basin or catchment. The characteristics of these river systems are described using some geometrical parameters as:

• Length
• Slope
• Speed
• Range
• Energy

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