water on and under ground. objectives define and describe the hydrologic cycle. identify the basic...
TRANSCRIPT
WATER ON AND UNDER GROUND
Objectives
• Define and describe the hydrologic cycle.• Identify the basic characteristics of streams.• Define drainage basin.• Describe how floods occur and what factors
may make them worse.• Define recurrence interval and show how it
is used to predict floods.• Define water table.• Identify two types of aquifers.
The Hydrologic Cycle
• Hydrology– The scientific study of water
• Evaporation– Water changes from a liquid into water
• Transpiration– Water taken up by plants passes into the
atmosphere
• Condensation– Water changes from a vapor into a liquid or a
solid
The Hydrologic Cycle
• Water in the Earth system– Deposition
• The process by which water changes from a vapor to a solid
– Precipitation• Water that has condensed in the atmosphere falls back to
the surface as rain, snow, or hail
– Surface runoff• Precipitation that drains over the land or stream channels
– Infiltration• The process by which water works its way into the ground
though small openings in the soil
The Hydrologic Cycle
The Hydrologic Cycle
The Hydrologic Cycle
How Water Affects Land• Streams and stream
flow– Stream
• A body of water that flows downslope along a clearly defined natural passageway
How Water Affects Land• Streams and
stream flow– Channel
• The clearly defined passageway through which a stream flows
– Straight– Meandering– Braided
How Water Affects Land• Streams and stream
flows– Gradient
• The steepness of a stream channel
– Discharge• The mount of water
passing by a point on a channel’s bank during a unit of time
– Load• The suspended and
dissolved sediment carried by a stream
How water Affects Land• Stream deposit
– Floodplain• The relatively flat valley floor adjacent to a stream
channel, • Inundated when the stream overflows its banks
How water Affects Land• Stream deposit
– Alluvium• Stream sediment• Unconsolidated
sediment • Recently deposited
(geologically speaking)
How water Affects Land• Stream deposit
– Delta
How water Affects Land
How Water Affects Land
• Drainage basin– The total area from which
water flows into a stream
• Divide– A topographic high that
separates adjacent drainage basins
• Lakes– Standing bodies of water
that have open surfaces, in direct contact with the atmosphere
Water as a Hazard and a Resource
• Floods– An event in which
a body of water overflows its banks
• Flood prediction and prevention– Flood frequency
curve– Recurrence interval– Channelization
Water as a Hazard and a Resource
• Hydrographs of stream discharge
Water as a Hazard and a Resource
Water as a Hazard and a Resource
Water as a Hazard and a Resource
• Flood Frequency Curve
Water as a Hazard and a Resource
• Surface water resources– Reliable water supply critical to human survival and health,
agriculture and other economic activities– Nearly 250 million people are designated as water-scarce
Case Study: Mono Lake
Freshwater Underground
• Ground water– Subsurface
water contained in pore spaces in regolith and bedrock
• Water table– The top surface
of the saturated zone
Freshwater Underground
• How groundwater moves– Porosity
• The percentage of the total volume of a body of rock or regolith that consists of open spaces (pores)
– Permeability• Measure of how easily a solid
allows fluids to pass through it
Freshwater Underground • How
groundwater moves (continued)– Percolation
• Groundwater seeps downward
• Flows under the influence of gravity
– Recharge• Replenishment of
groundwater
Freshwater Underground
• Where groundwater is stored– Aquifer
• A body of rock or regolith that is water saturated, porous, and permeable
– Aquiclude• A layer of
impermeable rock– Artesian well
Freshwater Underground• How groundwater
moves (continued)– Discharge
• Subsurface water leaves the saturated zone
• Becomes surface water
– Spring• Occurs where the
water table intersects the land surface
In Galveston, TX, pumping of groundwater causedSubsidence of property allowing sea water to flow In from Gulf of Mexico.
Freshwater Underground
• When groundwater dissolves rock– Karst topography– Sinkholes– Cave
• Underground open space
• A cavern is a system of connected caves
Lechuguilla Cave
Groundwater is the sole source of potable water for approx. 1.5+ million people in Suffolk County. Suffolk County is the most eastern county on Long Island and the location of our research.Population has increased due to urban sprawl from New York City since World War II, changing Suffolk County from predominantly agriculture land into urban land. Notable sources of groundwater contamination was summarized by Nemickas et. al. and include:
Salt water intrusion caused by pumping Nitrates from fertilizers, septic systems, animal waste Industrial contaminants such as heavy metals, degreasers, detergents, dyes, solvents Landfills Petroleum products Pesticides Coliform Road salt
Critical Thinking
• List the many ways we depend on the availability of fresh water in our daily lives.
• Where does your community obtain its water supply (i.e., groundwater, surface source)? Is the quantity or the quality of the water threatened?
• What would happen to the sea level and the shoreline if great ice sheets built up on the land?