Where in the world is the water??. More than 97% of all Earth’s water is in the oceans. Only <1 % of Earth’s water is available to us as water vapor, groundwater, and freshwater. The Hydrologic Cycle ( Water Cycle). Earth’s waters are constantly circulating. The driving forces are:
More than 97% of all Earth’s water is in the oceans.
Only <1 % of Earth’s water is available to us as water vapor, groundwater, and freshwater.
Earth’s waters are constantly circulating.
The driving forces are:
Controls the circulation of water on Earth.
Water makes a complete loop.
The journey is not always direct.
Saturated zone—water has filled all pore spaces.
Unsaturated zone—pores filled with water and air.
The water table
is the boundary
these two zones.
The depth varies with precipitation and climate.
Soil with rounded particles of similar size has higher porosity than soil with various sizes.
Groundwater flow rate =
cross-sectional area hydraulic gradient
It is important to keep this vital source of fresh water clean and contaminant free.
discontinuous, low-permeability layers in an unconfined aquifer trap water that is percolating downward.
Flowing groundwater can alter and change features at the surface:
and interbedded clays.
The clays leak water to the sand, then when
water is pumped out, the clays
shrink and compact, causing
Rivers sculpt and shape Earth’s surface:
Stream channels in high mountain areas cut into underlying rock.
Fast-moving rapids and beautiful waterfalls are characteristic of V-shaped mountain stream valleys.
Laminar flow—gentle, not impeded, often fast
Turbulent flow—impeded, “White water” and often slower
Stream speed - usually not constant along the length of a stream.
Average stream speed=discharge/cross-section
(River speeds never go more than 4-5 mph)
Stronger currents lift particles more effectively:
Slower along the stream bed
Greater near the surface.
Maximum flow speed occurs mid-channel.
Stream speed plays a role
Meandering streams create a wide belt of almost flat land: a floodplain.
When a flood occurs, sediment is deposited in the floodplain. Large, coarse sediment creates natural levees.
Drainage Divides- separate basins
The largest drainage divides are continental divides.Drainage basins and divides
A delta is where a flowing stream meets a standing body of water. The flow slows down and the stream dumps sediment.
The result is a fan-shaped deposit of new land.
Accumulation of snow and ice thick enough to move under its own weight
Alpine glaciers develop in mountainous areas, confined to individual valleys.
Cascades, Rockies, Andes, Himalayas
Continental glaciers cover broad expanses .
Antarctica and Greenland
When glacial ice melts, it drops a poorly sorted load of boulders, pebbles, sand, and clay.
Poor sorting is the hallmark that differentiates glacial sediment from material deposited by streams and winds.
The mass of a glacier changes over time.
As snow falls, accumulation makes the glacier grow.
As ice melts, sublimates, or breaks off, ablation occurs.
Wind blows everywhere, but its impact on sculpting the land is minor.
Impact is greatest where: