LESSON 7 GEOLOGY

• Groundwater


  is any water located beneath the surface of the ground with soil pores or fractures of rock.
• Groundwater


  is all water flowing through or stored within the ground, in both rocks and soils, and is generally clean.
• Groundwater engineering


  is the analysis, monitoring and often modelling of this water to better understand how much remains and if the water can be used.
• Hydrogeology


  is the study of interaction of water with geological systems and understanding where and how this water moves under the ground.
• PRECIPITATION


  is the ultimate source of all fresh water, and when it (rainfall) lands on the ground surface, it is dispersed through evapotranspiration, runoff or infiltration
• Convectional Precipitation


  Common in the tropics, the air close to the warm earth gets heated and rises due to its low density, cools to form cauliflower clouds which finally bursts into a thunder storm
• Frontal Precipitation


  When two air masses due to contrasting temperatures and densities clash with each other and condensation occur at the surface of contact, called "front" or "frontal surface"
• Orographic Precipitation


  • Mechanical lifting of moist air over mountain barriers causing heavy precipitation on the windward side
• EVAPOTRANSPIRATION


  Loss of water either from the water surface and soil surface or from plant leaves.
• Evaporation


  ______ If the loss is coming from free water surfaces (reservoirs, lakes, ponds, river channels, etc.) and soil surface (esp. when the groundwater table is very near the soil surface)
• Transpiration


  The process by which the water vapor escapes from the living plant leaves and enters the atmosphere
• RUNOFF


  Surface water flow into streams and rivers.
• INFILTRATION


  Seepage to the ground of runoff to become groundwater
• Meteoric water Connate water Juvenile water


  three (3) main sources of groundwater
• Meteoric water


  derived from precipitation (rain and snow). This consist of surface flows or runoffs that gradually infiltrates into the ground.
• Connate water


  present in the rocks from the time of their deposition in an aqueous environment. Incomplete compaction may cause retention of some water but these rocks; generally saline in nature
• Juvenile water or magmatic water


  are those found in the cracks and crevices or pores of rocks due to condensation of steam emanating from hot molten masses or magmas
• Subsurface zones


  • Regions below the surface of the earth may be found to exist in two subsurface zones or environments called vadose zone and phreatic zone. • The dividing line between vadose and phreatic zones is the groundwater table.
• Vadose zone


  the zone of aeration is the region above the water table in which soil pores may either contain air or water
• Soil-water zone


  have the roots of vegetation. Water content amount fluctuates due to moisture uptake from vegetation.
• Intermediate zone


  have the moisture levels remain at constant at field capacity of soil and rocks of the region
• Capillary fringe or capillary rise zone


  is the region where moisture rises due to capillary action and high cohesive forces of soil particles.
• Phreatic zone


  the zone of saturation is the region below the water table where the pores are filled with water
• Permeability


  s the ability of a rock to transmit water through its interconnected voids
• Permeability


  Is measured by hydraulic conductivity k, also known as coefficient of permeability
• aquifer, aquiclude, aquifuge and aquitard.


  - Rocks can be classified due to permeability:

  - Saturated formations are classified into four categories:
• Saturated formations


  are geological formations below the groundwater table in which water moves with different difficulty, hence, extraction are affected. These are the primary sources of extracted groundwater supply
• aquifer


  is a saturated formation of earth material which not only stores water but yield it in sufficient quantity. Thus, an aquifer has high permeability. These are the geological formations where groundwater occurs.
• Unconfined aquifer


  is open to earth's surface and to infiltration.
• Confined aquifer


  is overlain by less permeable materials, hence, cannot be infiltrated easily
• Perched aquife


  occurs in the vadose zone when an impermeable layer of rock surrounds a permeable layer.
• Artesian aquifer


  happens when the groundwater reaches the surface under the natural pressure of the aquifer
• Aquitard


  is a confining bed that retards but does not prevent the flow of water to or from an adjacent aquifer; a leaky confining bed. It cannot yield water to wells or springs, but may serve as a storage unit for groundwater.
• Aquiclude


  is a saturated formation, which, although porous and capable of storing water, does not transmit it at rates sufficient to furnish an appreciable supply for a well or spring.
• Aquifuge


  has no interconnected openings, entirely impermeable, hence cannot store or transmit water.
• Porosity (n)


  the void fraction is the measure of void ("emptiness") in a rock, relative to its total volume.
• Specific yield (Sy)


  effective porosity is the volume of water drained from storage by an unconfined aquifer per unit surface area of aquifer per unit decline of the water table:
• Specific retention (Sr)


  is the amount of water retained in storage in an unconfined aquifer per unit surface area of aquifer, due to capillary forces.
• J. Bear


  According to _______ (1979), effective porosity, specific yield and specific retention are related by a single equation:
• Hydraulic gradient


  is a vector gradient between two or more hydraulic head measurements over the length of the flow path.