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 Runoff is water that doesn’t soak into the ground or evaporate, but flows across earth’s surface  Factors that affect runoff 1. Amount of rain 2.

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Presentation on theme: " Runoff is water that doesn’t soak into the ground or evaporate, but flows across earth’s surface  Factors that affect runoff 1. Amount of rain 2."— Presentation transcript:



3  Runoff is water that doesn’t soak into the ground or evaporate, but flows across earth’s surface  Factors that affect runoff 1. Amount of rain 2. Length of time  Light rain over an hour has time to soak up  Heavy rain over less than an hour will run off because it can’t soak into the ground fast enough

4 3. Slope of land  Gravity causes water to move down slope  Water moves quickly down steeper slopes  Water moves slowly down gentler slopes  Slower movement=water soaked up by ground 4. Vegetation  Plants slow down runoff and help prevent soil from being carried away  Runoff will carry more soil and sediments in places lacking vegetation



7  Streams are parts of river systems  Can compare to a tree  Water comes from rills, gullies and small streams  Drainage basin is the area of land from which a stream or river collects runoff  All the water in a river system flows to the trunk (main river)


9  Stages depend on the slope of the ground over which the stream flows  3 classifications: 1. Young 2. Mature 3. Old  The stages of development do not always coincide with the actual age of the river

10  Flows swiftly  Slope is steep  Has a rough bottom  High level of energy  Erodes bottom of stream faster than its side

11  Flows smoothly through its valley  Rocks in the streambed over time are eroded by running water and sediments  Erosion takes place more on the sides than the bottom  This causes curves to develop called meanders

12  Flow through broad, flat floodplains  Drops load of silt near its mouth  Dropping of sediments forms a delta  A delta is an area of flat, fertile land extending into the ocean


14  As water moves through a river system it loses energy  This lose of energy causes sediments to be dropped along the way  Some sediments are carried a long way, while others only short distances  When sediments are deposited as the water empties into an ocean or lake, a deposit called a delta forms  Deltas are triangular or fan-shaped

15  When a river empties from a mountain valley into a flat plain, the deposit is called an alluvial fan


17  Water that soaks into the ground collects in the pores and empty spaces in the soil or rock is called groundwater  14% of all water exists as groundwater  Groundwater system has connecting pores  Soil and rock are permeable if pores are connected and water can pass through them ◦ Water flows easily through ◦ Ex: sandstone-permeable rock

18  Impermeable rock or soil doesn’t have well connected pores or few pore spaces ◦ Water doesn’t flow easily through ◦ Ex: granite, clay  Groundwater keeps going deeper into Earth’s crust until it reaches a layer of impermeable rock  Zone of saturation is where all the pores in the rock are filled with water  The upper surface of this zone is the water table


20  The amount of groundwater is limited  Many people get their water from wells that have been drilled into the zone of saturation  During a draught, the water table drops  This is why it is important to conserve water

21  A good well extends deep into the zone of saturation  Groundwater flows into a well and a pump brings it to the surface  If water is taken out of well faster than it can be replaced, wells can go dry  If too much water is pumped out in area, the land can drop or sink  Artesian well-doesn’t need a pump to bring water to the surface

22  Water in an artesian well rises to the surface due to pressure  Artesian wells are very rare because the aquifer needs to be located between 2 impermeable layers that are sloping  Water enters at the high part of the slope and exits through a well at the low part of the slope due to the pressure created by the higher part of the aquifer

23  Springs are found on hillsides where the water table meets a sloping surface  Water flows out of the spring  Source of freshwater  Usually water comes to the surface as a cool temperature  When water comes to the surface after being heated by hot rocks, it is called a hot spring

24  Is a hot spring that erupts periodically  Groundwater is heated to high temperatures causing it to expand underground  The expansion forces some of the water out of the ground  Most of the water turns into steam  Ex: Old Faithful, Yellowstone National Park


26 1. Groundwater mixes with carbon dioxide to form carbonic acid (weak) ◦ CO 2 is absorbed by groundwater in the soil ◦ CO 2 is absorbed by rainwater from the air 2. Acidic water flows through rocks, dissolving the rock (limestone) 3. Cracks in the limestone get bigger until an opening is formed. This is called a cave!

27  Stalactites form from deposits of calcium carbonate. ◦ Water dripping inside the cave has calcium ions dissolved in it ◦ This water evaporates and deposits calcium carbonate. ◦ When this happens over and over stalactites form.  Stalagmites form when the drops of water fall to the floor of the cave  A sinkhole is a depression on the surface of the ground that forms when the roof of a cave collapses or when material near the surface dissolves


29  3 forces shape shorelines 1. Waves  Crash against the shorelines  Very powerful force  Erode and move away large amounts of material 2. Currents  Longshore currents are created by waves that hit at a slight angle

30  Carry tons of loose sediments 3. Tides  Outgoing tides carry sediments away from the shore  Incoming tides bring new sediments to the shoreline  Work with waves to shape shorelines


32 RockySandy  Consist of rocks and cliffs  Waves and sediments slowly wear away rocks  Rock parts that break off are carried away by longshore currents  Smooth, gently sloping beaches  Made up of grains of quartz or shell fragments  Fragments range from stones to fine sand  Some beaches have different colored sands  Ex: Hawaii-black, made of basalt  Ex: Jamaica-white, made of coral and shell


34  Are sand depositions that lay parallel to the shore but are separated from the mainland  Start out as underwater sand ridges  Hurricanes and waves help form the islands  Last only a few years to a few centuries  Storms and waves also erode the barrier islands and cause erosion to beachfront developments

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