Groundwater Systems

Importance of Groundwater Earth’s Water Only 3% of the Earth’s water is fresh & potable. Freshwater Although groundwater is only 0.6% of the Earth’s water it is 14% of the fresh water. Freshwater – no Glaciers Excluding glaciers, groundwater is 94% of the available freshwater. Groundwater usage Drinking water for > 50% of the population Accounts for 40% of the Irrigation water Provides 25% of industry’s needs

Using the terms below complete the concept map. A) saturated zone B) unsaturated zone C) partially saturated zone D) sandstone E) shale F) confining unit G) unconfined aquifer H) confined aquifer I) porosity J) permeability K) aquifer M) water table L) infiltration Rock/Sediment With high 1) _______ (storage of water) & high 2) _________ (transmission of water) With low 1) _______ & low 2) _________ 3. 4. For example Between 2 confining layers Near the surface For example 5. 6. 7. 8. Pores are filled with water & air Pores are filled with water 1 – I 2 – j 3 – K 4 – F 5 – D 6 – G 7 – H 8 – E 9 – B 10 – A 1 pt for each correct answer 9. 10. Daily Assignment

How does water get below the Earth’s surface Water infiltrates in recharge areas – areas at the Earth’s surface that allows water to move through it

Is groundwater an underground river? Groundwater occurs everywhere Zone of Saturation – all the pore space is filled with water But not all the ground is saturated Zone of Aeration – pores are filled with air and water Water Table – upper surface of the zone of saturation

Where is groundwater stored? Porosity Percentage of total volume of rock or sediment that consists of voids (pores) Function of Size and shape of the grains The packing of the grains Sorting of the grains

Permeability Ability of a material to transmit a fluid (water) The interconnectedness of the pores Shales have a low permeability Sandstones have a high permeability

Unconfined Aquifer – top of the aquifer is exposed to the atmosphere Confined Aquifer – an aquifer lying between two aquitards, water is under pressure

The water table is a subdued replica of the topography

Groundwater movement Groundwater is not stagnant, it responds to climatic changes i.e. the water moves up wet periods & moves down during dry periods

Energy Drives Water Movement Groundwater moves from high “energy” to low “energy” Groundwater has two types of energy Potential (stored) energy – controlled by elevation & gravity – how far can the water drop Kinetic (in motion) energy – controlled by pressure and velocity (very small can be ignored) Total of potential and kinetic energy is hydraulic head Groundwater is moving, but slowly

Artesian Conditions Artesian is applied to any situation where the groundwater in a well rises above the level where it is initially encountered. Associated with confined aquifers – due to excess pressure from overlying material