Thinking Questions Why is Freshwater so Rare? What is a River? What makes up a river? What creates rivers? What is a flash flood? What is needed to have a flash flood occur? Why is our area of NC prone to Flash floods? Why are mountains also prone to Flash Flooding?

Freshwater Systems You will be able to: Explain how Rivers shape the land Identify conditions which cause flooding Identify the different zones and characteristics of River Systems

Water Cycle Fresh Water comes from the Water Cycle Water Cycle Diagram: herehere

Where is the Water? 71% of Earth is covered by water 29% Terrestrial Surface 3% of water is Fresh 97% of all water is salt water

Where’s the FRESHWATER?

Where’s the Freshwater? Where’s the Freshwater? Water in Ice caps completely frozen all year round Making ground water the largest supplier of the world’s FRESH WATER!

The 1%: How Rivers Form All Rivers form from Run-off Run-off is water that is not absorbed by the ground. Produced from precipitation and seasonal melting of snow and glaciers Run-off rates may change at different locations within a River System

What affects Run-Off Rate? (3 things) Soil Type – Major factor in determining run-off rates. Different soil types have different abilities to containing water. Precipitation/Melting amounts- Amount of water that is able to fall upon ground Topography of Land- Hills produce more run-off than flat areas because gravity pulls water down the sides of the hill and not into the soil

Soil Types Soils have different Run-off traits because of 2 primary factors Porosity- amount of empty spaces between soil particles Permeability- how well empty spaces are aligned. If both values are low, high run off rates will occur 3 Basic soil Types in NC, gravel based, clay based, or sand based

Soil Types (Con’t) Different Soil types traits are best described using 2 terms; Aquifer- Material that allows water to travel through it easily (high porosity, high permeability) Aquitard- material that DOES NOT allow water to travel through it easily. (low porosity, low permeability)

What River Systems Share 1 st Zone- Headwaters Small Tributaries/streams formed along sides of mountains Streams are narrow but deep in places High erosion occurs here Animals small in size and streamlined

What River Systems Share 2 nd Zone- Downriver Tributaries merge and form larger water system; Current here fast and strong ”White Water rafting” Rivers wider, straighter high erosion; little deposition Animals larger and still streamlined

What River Systems Share Flood Plain- 3 rd zone Rivers begin to twist and turn, Current slows dramatically River is at its widest but also fairly shallow Erosion rates equal Deposition rates; Bends in rivers called Meanders Organisms are largest here; not as streamlined.

What River Systems Share 4 th Zone- Estuary/Mouth/Delta Where River empties into Sea Current here very slow No Erosion, High Deposition rates Organisms actually get smaller in size as you approach ocean,

What River Systems Share Watershed- Entire area of Land that gives run-off to a River System Divide- Geographical region which separates River Systems; Usually a mountain range