water in what ways have you used water today? how much water is used to make a 1kg burger?
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How much water is used to make a 1KG burger?TRANSCRIPT
Water
In what ways have you used water today?
How much water is used to make a 1KG burger?
4000 Litres of Water
How much water is used to make a pair of leather shoes?
16, 000 Litres of Water
Where does the water we use come from?
11: Groundwater Water resources Geologic Agent
Earth materials• Rock• Sediment (Soil)• Fluids (Water)
Geologic processes• Form,• Transform and• Distribute (redistribute) Earth materials Water is a primary agent of many (all?)
geologic processes
Hydrogeology DefinedWater Earth
Hydrogeology Defined Water EarthInteractions go both ways GeologyGroundwater
Geology controls flow and availability of groundwater because
Groundwater flows through the pore spaces and/or fractures
Groundwater geologic processes.
Interactions
Hydrogeology Defined WaterEarth InteractionsGeology controls groundwater flow
Permeable pathways are controlled by distributions of geological materials.
Shale
ShaleSandstone
Hydrogeology Defined WaterEarth InteractionsGeology controls groundwater flow
Permeable pathways are controlled by distributions of geological materials.
Groundwater availability is controlled by geology.
Hydrogeology Defined WaterEarth InteractionsGeology controls groundwater flow
Permeable pathways are controlled by distributions of geological materials.
Groundwater availability is controlled by geology. Subsurface contaminant transport is controlled by geology.
Hydrogeology Defined WaterEarth Interactions
Groundwater controls geologic processes Igneous Rocks:
Groundwater controls water content of magmas.
Metamorphic Rocks: Metasomatism (change in composition) is controlled by superheated pore fluids.
Volcanism: Geysers are an example of volcanic activity interacting with groundwater.
Hydrogeology Defined WaterEarth InteractionsGroundwater controls geologic processes Landforms: Valley development and karst topography are
examples of groundwater geomorphology. Landslides: Groundwater controls slope failure. Earthquakes: Fluids control fracturing, fault movement,
lubrication and pressures.
Ground Water Zones Degree of saturation
defines different soil water zones
Ground water and the Water cycle Infiltration Infiltration capacity Overland flow Ground water
recharge GW flow GW discharge
Porosity and Permeability Porosity: Percent of
volume that is void space.
Sediment: Determined by how tightly packed and how clean (silt and clay), (usually between 20 and 40%)
Rock: Determined by size and number of fractures (most often very low, <5%) 1%
5%30%
Porosity and Permeability
Permeability: Ease with which water will flow through a porous material Sediment: Proportional to
sediment size GravelExcellent SandGood SiltModerate ClayPoor
Rock: Proportional to fracture size and number. Can be good to excellent
Excellent
Poor
Porosity and Permeability Permeability is not
proportional to porosity.
Table 11.1
1%
5%30%
Water table: the surface separating the aerated zone from the saturated zone.
Measured using the water level in a well
The Water Table
Fig. 11.1
Precipitation Infiltration Ground-water
recharge Ground-water flow Ground-water
discharge to Springs Streams and Wells
Ground-Water Flow
Velocity (speed) is proportional to Permeability Slope of the water
table
Ground-Water Flow
Fast (e.g., cm per day)
Slow (e.g., mm per day)
Infiltration Recharges ground
water Raises water table Provides water to
springs, streams and wells
Natural Water Table Fluctuations
Reduction of infiltration causes water table to drop Wells go dry Springs go dry Discharge of rivers
drops Artificial causes
Pavement Drainage
Natural Water Table Fluctuations
Pumping wells Accelerates flow
near well May reverse
ground-water flow Causes water table
drawdown Forms a cone of
depression
Effects of Pumping Wells
Pumping wells Accelerate flow Reverse flow Cause water
table drawdown Form cones of
depression Low river
GainingStream
GainingStream
Pumping well
Low well
Low well
Cone of Depression
Water TableDrawdown
Dry Spring
Effects of Pumping Wells
Dry river
Dry well
Effects of Pumping Wells
Dry well
Dry well
LosingStream
Continued water-table drawdown May dry up
springs and wells May reverse flow
of rivers (and may contaminate aquifers)
May dry up rivers and wetlands
Ground-Water/ Surface-Water
Interactions Gaining streams
Humid regions Wet season
Loosing streams Humid regions, smaller
streams, dry season Arid regions
Dry stream bed
Confined Aquifers & Artesian Wells
Hydraulic Head
Cap Rock
Impermeable Layer
Confined Aquifers
Ground-Water Contamination Dissolved contamination travels with ground water flow
Contamination can be transported to water supply through an aquifer’s down flow
Pumping will draw contamination into water supply
Ground-Water Contamination Leaking Gasoline
Floats on water table
Dissolves in ground water
Transported by ground water
Contaminates shallow aquifers
Ground-Water Contamination Dense solvents
E.g., dry cleaning fluid (TCE)
Sinks past water table
Flows down the slope of an impermeable layer
Contaminates deeper portions of aquifers
Ground-Water Contamination Effects of pumping
Accelerates ground water flow toward well
Captures contamination within cone of depression
May reverse ground water flow
Can draw contamination up hill
Can cause saltwater intrusion
Ground Water Action Ground water
chemically weathers bedrock E.g., slightly acidic
ground water dissolves limestone
Caves are formed Permeability is increased Caves drain Speleothems form
Ground Water Action Karst Topography
Caves (Speleothem) Sink holes Karst valleys
Disappearing streams Giant springs