april 2001 copyright by dr. isiorho1 quick review rivers and groundwater

April 2001 Copyright by Dr. Isiorho

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Quick ReviewQuick Review

Rivers and Groundwater


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Surface WaterSurface Water

The Hydrologic CycleTake a look at St. Joseph or Ste. Mary’s

river in Ft. Wayne and relate that to the quotation below

“All the rivers run into the sea, yet the sea is not full. To the place from which the rivers come, there they return” Ecle. 1:7


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Earth’s WaterEarth’s Water

How much water is there? Approx. 1.36 billion km3 (326 million mile 3) and this amount is fairly constant

The continuous circulation of water through the ocean, land and the atmosphere is the process called hydrologic cycle

Distribution of Earth’s water~97 % in ocean; ~2.35% ice/glacier; ~0.65% Lakes,

Streams, Groundwater, Atmosphere The largest amount of fresh available to humans-

groundwater Glacier and Ice – largest amount of fresh water


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Things you need to know about Things you need to know about StreamsStreams

A stream is a surface water flow confined to a channel Floodplain- flat land immediately surrounding a stream which may be

submerged if a river overflows its bank Drainage Basin- land areas that supply surface water to the river Drainage Divide- topographic highland that separates two adjacent

drainage basins Tributaries- streams that contribute water to main (trunk) stream Distributaries- main river splits into small channels Graded Stream- state of temporary equilibrium Base level- lowest point to which a river can erode Discharge- the amount of water that flows through a given area

(Q=V*A) Types of Rivers- Effluent, Influent, Exotic, Perennials, Intermittent,

Ephemeral


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Stream ErosionsStream Erosions

Graded Streams- Aggregation- too much sedimentsDegradation- occurs when there is less sedimentsGradient- know how to calculate this

Stream ErosionAbrasionHydraulic liftingDissolution


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*Drainage Patterns*Drainage Patterns Streams erode their networks of tributary valleys and distinctive drainage

patterns. A drainage pattern is a reflection of the underlying rock material or structure.

Drainage Types (Patterns) Dendritic Radial Rectangular Trellis Annular Parallel Deranged

Stream Piracy Channel patterns- straight, braided or meandering, oxbow lake


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Stream TransportStream Transport

Velocity of sediment transport is controlled by its discharge

Stream Capacity or carrying Capacity is the total volume of sediments (load) it can carry and it is controlled by its discharge

Competence- the maximum size of sediments (load) a stream can carry and it is controlled by its velocity

Sediments are transported in the following formatSuspended loadBed loadDissolved load


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Stream DepositionStream Deposition

Alluvium- sediment materials that settle from water Point bar- sediments deposited within the channel Flood plain Deposits

Levees Backswamp- deposits that make a flood plain’s wetland

Alluvial fans- formed where stream valley widens Delta- formed by the deposition of sediments in

standing water where the main stream breaks into smaller channels


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Flood ControlFlood Control

Floods occur when water flow exceeds a river’s channel capacity. The 1982 Flood in Ft. Wayne

ManagementForecast and Prediction

Flood Control StructuresLevees and Flood walls

Alteration of Channels- channelization Flood way zone- structural development

restriction


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GroundwaterGroundwater

Types of groundwater– hygroscopic water (not available to plants), capillary water, and gravity water.

Porosity is the ratio of the voids to sediment (rock) volume The surface water will percolate downwards until it

reaches a zone where all the pore spaces are saturated with water

The line that separates the saturated from unsaturated zone is the Water Table

A geologic material that is porous, permeable, saturated and will yield enough water when a well is drilled into it is called an AQUIFER


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Groundwater MovementGroundwater Movement For groundwater to flow- need porous and permeable

materials Porosity is the percent of pore spaces in relation to the

total soil/rock/sediment volume Permeability is a measure of the ability of rock/sediment to

transmit fluid Groundwater flow occurs when there is a hydraulic

gradient Hydraulic conductivity is the ability to transmit

groundwater. Typical groundwater flow is slow ~0.5 – 1.5 cm/day (0.2 - 0.6 in/day). The slow movement stores the water making it available to humans.


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Tapping Groundwater Tapping Groundwater ReservoirReservoir

Groundwater depth is a reflection of local topography and prevailing climate

Aquifers are permeable water-bearing bodies of geologic materialsUnconfined and Confined aquifers

Aquiclude and Aquitard Artesian flow- water flows to the surface from wells without

pumpingPotentiometric surfaceNatural SpringsGeysers- intermittent surface emission of hot

water/steam


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Groundwater PumpingGroundwater Pumping Features Associated with Pumping

Cone of depression- local depression in water around pumping well

Subsidence- compressed land due to aquifer depletion Salt water intrusion- due to over pumping along coast line

Greater demand for water- leads to groundwater depletion and introduction of pollutant

Excessive withdrawal of groundwater from aquifer may result in…land subsidence, change in groundwater flow pattern, cause drawdown, depletion of aquifer

Solutions- enhance recharge, water transfer, conservation, desalinization, and use of iceberg


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Groundwater Groundwater Contaminants/PurificationContaminants/Purification

Natural occurring solutes- Chlorine, Arsenic, Mercury, and Selenium

Manufacturing contaminants- from household products: cans of paint, solvent, cleanser etc.

Natural Groundwater PurificationFiltration- adhere to clay particlesDecomposition- some decompose completely by

oxidationBacteria action- organic solids consumed by

microorganis


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Products of GroundwaterProducts of Groundwater Karsts

Water reacts with carbon dioxide to form weak carbonic acid which then attacks limestone

H2O + CO2 => H2CO3 + CaCO3 => Ca++ HCO3 –

Caves- natural underground cavities and most common geological product of limestone dissolution

Cave deposits- spelotherms are deposits on cave surfaces in a variety of forms: travertine, Stalactite, Stalagmite, banded draperies or drip curtains

Growth of spelotherm- depends on the solution and porosity of surface material, climate, topography, and vegetation


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Karsts TopographyKarsts Topography Surface expression of the geology of dissolved limestone

and work of near surface water Cave and Karsts landscapes are extremely sensitive- so

need to be protected Landform

Sinkholes-circular surface depressionDisappearing Streams- flow through sinkholes may emerge as

spring several kilometers awayNatural Bridge- series of neighboring sinkholes expand and join

together

april 2001 copyright by dr. isiorho1 quick review rivers and groundwater

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