Surface Water and Groundwater

Running Water and Groundwater % of where the Earth’s water is located –Oceans (salt water) – 97 % –Freshwater trapped in Glaciers/ice – 2 % –Freshwater available to us - < 1 % Water cycle - the continuous circulation of earth’s water supply –Powered by the sun

Elements of the Water Cycle Evaporation = liquid to gas Condensation = gas to liquid (forms clouds) Precipitation = water returns to earth (rain, snow, ice, sleet, etc.) Infiltration = water that soaks into ground Runoff = water that flows across the ground Transpiration = water that plants release into the atmosphere (gas to liquid)

Water Cycle

Water Cycle (cont.) The Earth’s water cycle is balanced Earth’s annual precipitation = the amount that evaporates Local imbalances do exist like droughts and floods

Stream Flow Velocity – distance water travels in a period of time –Some are slow, some are fast –Highest velocities are in the middle of the channel when it is straight –When it bends, the velocity is highest in the outside bank/bend –Ability of a stream to erode & transport materials depends on velocity

5 Stream Velocity Factors 1.Gradient = slope (how steep or flat) 2.Shape = crooked vs straight 3.Size = wide vs narrow & deep vs shallow 4.Roughness = smooth vs rough 5.Discharge = the volume of water flowing past a certain point per unit of time (m 3 /s)

Stream Profile Cross sectional view of a stream Page 160

Stream Profile Changes Decrease as you go downstream –Gradient –Roughness Increase as you go downstream –Discharge –Velocity –Depth –Width The ability of a stream to erode increases as the discharge increases.

French Broad River Headwaters North Fork, French Broad River West Fork, French Broad River

French Broad Decreasing Gradient Going Downstream Middle French Broad Lower French Broad

Stream Terms Channel – where the main flow of the river is found Bank – the side of the river

Stream Terms Tributary – anything that empties into another stream Base level – the lowest point to which a stream can erode its channel Meander – bends/curves in a river/stream Oxbow lake – a meander that gets cut off from the main stream and form a small lake.

Meanders and Oxbow Lake

Stream Erosion The ability of stream to carry a load (sediment) is dependent upon 2 factors: –Competence - the largest particles the stream is transporting –Capacity – the maximum load it can carry

Sediment Transportation 3 types 1.Dissolved Load – sediment that is dissolved in the stream/river  Usually comes from groundwater 2.Suspended Load – the visible cloud of sediment a stream carries  Where a stream carries most of its load 3.Bed Load – sediments that are too large to be carried in suspension  Move along the stream/river bed

Stream Deposition As the stream slows down material begins to settle out Larger materials settle out first Levee – accumulation of sediment along the river banks

Stream Deposition Delta – a triangular accumulation of sediment formed where a stream enters a lake/ocean

Stream Depostion Alluvial Fan – forms when a stream slows at the mouth of a mountain canyon

3 Stages of Stream Development 1.Young 2.Mature 3. Old

Young Rivers fast straight narrow rapids v-shaped valleys

Mature Rivers slower meanders wider

Old Rivers slowest meanders and oxbows widest

Flooding Flood plain – flat areas along rivers that occasionally flood –Where sand and rocks are deposited on the side of the river Things that increase flooding: –Paving –Excess precipitation –Vegetation Removal Methods of flood control –Dams and levees –Limiting development

Ohio River Flooding

Drainage basin - the land area that contributes water to a stream Divide – imaginary line that separates one drainage basin of one stream from another

Groundwater Zone of saturation – area below ground where all the pore spaces are completely filled with water Zone of aeration – all the pore spaces are not completely filled with water Water table – the line that divides the two

Groundwater Porosity – the percentage of the total volume of rock (or sediment) that consists of pore spaces Permeability – how well water moves through the rock/sediment –Well rounded and well sorted grains = high porosity Aquifer – rock layers or sediment that allow groundwater to flow freely (sandstone)

Groundwater Springs – form whenever the water table intersects the surface of the ground Hot springs – water is heated from magma just below the surface Geysers – intermittent hot spring/fountain that periodically erupts (Old Faithful)

Groundwater Wells – a hole bored into the zone of saturation –A pump is needed –Cone of depression Artesian wells – groundwater rises on its own under pressure and no pump is needed

Groundwater Environmental Problems Overuse and contamination threatens groundwater supplies in some areas Contamination Fertilizers Pesticides Highway salts Chemicals Industrial wastes Causes land subsidence with too much withdrawal

Land Subsidence

Groundwater Contamination

Caverns A naturally formed underground chamber Usually forms in limestone from carbonic acid dissolving the rock Dripstones –Travertine – Calcium carbonate deposits –Stalactites – form from the ceiling –Stalagmite – form on the floor and reach toward the ceiling

Stalactites and Stalagmites

Karst Topography limestone areas with many caves and sinkholes (collapsed caves)

Sinkholes

Glaciers

Glaciers 10% of the Earth is covered in glaciers Thick mass of ice that forms on land over hundreds or thousands of years

Glaciers Act like bulldozers while they move –Move rocks and sediments with them and keep them with them until they melt Iceberg – a mass of ice floating the water –A piece of a glacier that has broken off –Only about 10% of it is above water

Erosion by Glaciers 5 types 1.Glacial trough 2.Hanging valley 3.Cirque 4.Arete 5.Horn 6.Striations

Glacial Trough A “V-shaped” valley that has been eroded into a “U-shaped” valley

Hanging Valley Valleys that are higher than the main glacial trough

Crique Bowl-shaped depression at the head of a glacial valley –Surrounded on 3 sides by steep rock walls

Arete Sharp edged ridges left by glaciers

Horn Sharp pyramid shaped peaks left by glaciers

Glacial Striations Groves left in the rock when the glacier melts