Dr V Hydrogeology PDF

INTRODUCTI ON TO HYDROGEOL OGY EAG 141 GEOLOGY FOR CIVIL ENGINEER BY VYNOTDNI RATHINASAMY  HYDROLOG INTRO OF Y CYCLE & 01 HYDROGEO LOGY 02 GROUND WATER LITHOLOGY CLASSIFICATI 03 OF...

INTRODUCTI ON TO HYDROGEOL OGY EAG 141 GEOLOGY FOR CIVIL ENGINEER BY VYNOTDNI RATHINASAMY  HYDROLOG INTRO OF Y CYCLE & 01 HYDROGEO LOGY 02 GROUND WATER LITHOLOGY CLASSIFICATI 03 OF AQUIFERS 04 ON OF AQUIFER IMPACT ON WATER GROUNDWAT 05 MOVEMENT OF AQUIFER 06 ER CONDITION INTRODUC TION HYDROLOGY The science of the occurrence, distribution, and movement of water and chemistry of ALL waters of the earth HYDROGEOL OGY interrelationship of Examine geologic materials and flowing water HYDROLOGI C CYCLE PRECIPITATION EVAPORATION Water falls down to Earth’s surface Water vaporation SURFACE RUNOFF GROUNDWATER Water from rain/snow etc flows Groundwater fills spaces between over the land surface soil particles and fractured rocks below the earth surface HYDROLOGI C CYCLE circulation of water in the environment “If there is magic on this planet, it is contained in water.” —LOREN EISELEY WATER Subsurface water that occurs beneath the water table in fully saturated soils and rocks Groundwater plays a key role in hydrologic cycle and is an important sources Fun Facts Groundwater represents close to 99% of all unfrozen fresh water in the world. Groundwater makes up one third of all water being used, provides almost half of the world's population with domestic water, and is the source of almost half of the water used for irrigation worldwide.  SURFACE WATER VS GROUND WATER Surface Water vs Groundwater -Determine 5 differences between surface water and groundwater and submit during next class- FACTORS AFFECTING GROUND WATER OCCURANCE VEGETATION TOPOGRAPHY AND RAINFALL RUNOFF LITHOLOGY AND AQUIFER  “A geologic unit capable of storing and transmitting water to wells” An aquifer is an underground layer of AQUIFER water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well. The study DESIGNof water flow in aquifers and the characterization of aquifers is called hydrogeology. Aquifers may occur at various depths. Those closer to the surface are not only MATERIALS more likely to be used for water supply and irrigation but are also more likely to be topped up by the local rainfall. EMPLOYEES Fun Facts In 2013 large freshwater aquifers were  Aquiclude: A water-bearing layer of rock or sediment that is incapable of transmitting water Aquifer: A water-bearing layer of rock or sediment capable of transmitting significant quantities of water Aquitard: A water-bearing layer of rock or sediment that TERMINOLOGY transmits small quantities of water in relation to Aquifer Aquifuge: A impermeable unit that will never store nor transmit water (e.g. Layers of solid salt) Confined Aquifer: An aquifer whose upper and lower AQUIFER boundaries are defined by Aquicludes. Drawdown: the amount of water level decline in a well due to pumping. Usually measured relative to static (non- pumping) conditions. Unconfined Aquifer: An aquifer in which the water table forms the upper boundary. Potentiometric Surface: an imaginary surface to which water would rise in wells from a given point in confined aquifer. The water table is a particular potentiometric surface for unconfined aquifers. CLASSIFICA Saturated TION OF vs AQUIFER unsaturate d Aquifers vs aquitard Confined vs unconfine d  The Earth's crust can be divided into two SATURATE regions: the saturated zone or phreatic zone (e.g., aquifers, aquitards, etc.), D VS where all available spaces are filled UNSATURA with water, and the unsaturated zone (also called the vadose zone), where TED there are still pockets of air that contain some water but can be filled with more water. The unsaturated zone, immediately below the land surface, contains water and air in the open spaces, or pores. The saturated zone, a zone in which all the pores and rock fractures are filled with water, underlies the unsaturated zone. The top of the saturated zone is called the water table  Aquifers are typically saturated regions of the subsurface that produce an AQUIFER economically feasible quantity of water to a well or spring (e.g., sand and gravel or VS fractured bedrock often make good aquifer materials). AQUITARD An aquitard is a zone within the earth that restricts the flow of groundwater from one aquifer to another. A completely impermeable aquitard is called an aquiclude or aquifuge. Aquitards comprise layers of either clay or non- porous rock with low hydraulic conductivity. Aquiclude: High Porous But Impermeable. Ex; Clay Aquifuge: Impermeable body of rocks with no interconnected opening: Ex; CONFINED VS UNCONFIN ED WATER MOVEMENT IN Water movement in aquifers is highly dependent of the permeability of the aquifer material. AQUIFER In permeable materials groundwater may move several meters in a day; in other places, it moves only a few centimeters in a century. Groundwater movement can be assessed using established hydraulic principles and data on the characteristics of an aquifer. The ability of an aquifer to receive, store or transmit water depends on the rock properties within the aquifer. Groundwater flow theory is based on equations developed from measurements in unconsolidated sediments (porous media). Groundwater in aquifers between layers of poorly permeable rock, such as clay or shale, may be confined under pressure. If such a confined aquifer is tapped by a well, water will rise above the top of the aquifer and may even flow from the well onto the land surface. Water confined in this way is said to be under artesian pressure, and the aquifer is called an artesian aquifer. Why Hydrogeology Plays Such An Important Role In The Thailand Cave Rescue Operations IMPACT ON GROUNDWATER Discharge to CONDITIONS FROM CIVIL surface/groundwater Discharge of polluting ENGINEERING WORK substances from construction activities. Pathway for groundwater flow Risk of pollution from near surface activities. Change in groundwater level and quality Ground settlement occurs whenever the groundwater level is lowered by abstraction THANKS No Question, perhaps? VYNOTDNI RATHINASAMY