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Erosion
Midterm 2014
| Question | Answer |
|---|---|
| What are the 6 processes of erosions? | gravity, water, wind, ice, chemical, biological |
| Describe erosion by GRAVITY? | DOWN SLOPE MOVEMENT of materials – mass wasting; movement of materials from high to low elevation – landslide |
| Define Erosion? | the weathering and or transport of solid materials (sediment, soil, rock and other particles) |
| Name 6 impacts of erosion? | air quality, habitat destruction, water pollution, loss of nutrients, sediment loading, loss of life |
| What are the 6 processes of erosions? | gravity, water, wind, ice, chemical, biological |
| Describe erosion by GRAVITY? | DOWN SLOPE MOVEMENT of materials – mass wasting; movement of materials from high to low elevation – landslide |
| What are the two types of WIND erosion? | Deflation and Abrasion (ecological succession) |
| Define Deflation? | the movement of particles through wind circulation to another location (ex. Dune creation) |
| Define Abrasion? | suspended particles in the air impact against other objects |
| What are the four factors involved with WATER erosion? | 1. Rainfall Impact (SPLASH EROSION) – dislodges soil particles – if on downslope 2. Overland flow of soil particles in suspension (SHEET RUN) 3. Scour – concentrated flow in water courses (RILLS) 4. Slope failure – mass movement, slippage (MASS MOVEMENT) |
| Describe Ice erosion? | movement of particles with glacial movement, or fracture of rocks through ice formation in pores and cracks |
| Describe CHEMICAL erosion? | decomposed, dissolved or loosened by chemical processes to form residual materials |
| What are the different processes of CHEMICAL erosion? | chemical weathering, carbonation, hydrolysis, oxidation and acid rain |
| Describe Biological erosion? | movement/breakdown of particles by animals/insects/birds/plants |
| What can affect the RATE OF EROSION? | climactic factors (temp.; precipitation), geologic factors (soil type, permeability, slope), biological factors (presence/absence of plants, types of organisms, land uses |
| What is the universal soil loss equation? | A = R x K x LS x C x P; used to predict erosion due to water |
| Universal Soil Loss Equation A = R x K x LS x C x P – A? | erosion soil loss in TONS/ACRE/YEAR |
| Universal Soil Loss Equation A = R x K x LS x C x P – R? | rainfall factor |
| Universal Soil Loss Equation A = R x K x LS x C x P – K? | soil erodibility factor |
| Universal Soil Loss Equation A = R x K x LS x C x P – LS? | field length and slope factor |
| Universal Soil Loss Equation A = R x K x LS x C x P – C? | vegetative cover and management factor |
| Universal Soil Loss Equation A = R x K x LS x C x P – P? | practises used for erosion control |
| What are 4 impacts of poor agricultural practices? | sediment loading, increased nutrient input in watercourse (EUTROPHICATION), loss of productive land, decreased crop production (increased food cost) |
| What are the four tillage practices? | Conventional tillage (less than 15% crop residue), Reduced tillage (leaves 15 – 30% crop residue), Conservation tillage (leaves more than 30% crop tillage). No – till (leaves almost all plant residue) |
| What are 3 erosion control strategies for agriculture? | buffer strips; grassed waterways (natural or constructed) seeded with grass to protect from erosion runoff of adjacent cropland, conducts water away from fields; taking steep slopes out of production |
| What are the four types of irrigation? | drip; sprinkler; furrow; flood irrigation |
| What is the most efficient method of irrigation? | drip; frequent slow application of water to soil, most efficient method, LITTLE SOIL LOSS |
| Can sprinkler irrigation lead to soil loss? | yes, the overhead application of water to crops can allow water to land with great force, it is best to use this method with established crops |
| What is furrow irrigation? | irrigation from channels used between rows in crops , constant maintenance, large volumes of soil removed |
| What is flood irrigation? | whole field surface is inundated with water, high rates of evaporation, large volumes of soil removed |
| What is the Dust bowl? | period of severe dust storms causing major ecological and agricultural damage to prairie lands (US and CAN) from 1930 – 1936 |
| _____ million acres of farmland lost due to dust storms by 1934. | 100 |
| What was Black Sunday? | April 15, 1935 |
| What are Aeolian (or Eolian) processes? | processes that pertain to the activity of the winds and specifically to the winds ability to shape the surface of the earth. |
| ________ __________ soils have surfaces which are covered with coarse fragments. | wind eroded |
| What are the three types of wind erosion? | Suspension, Saltation, and Surface Creep |
| Describe the method of wind erosion known as Suspension? | very small soil particles keep in suspension by the wind (particles less than 0.00mm, types – hummus, clay, silt) |
| Describe the method of wind erosion known as Saltation? | moved by wind in succession of bounces (particles 0.05 mm to 0.5 mm, types – fine sand) |
| Describe the method of wind erosion known as Surface Creep? | movement of very coarse sands, 1mm to 2 mm in diameter, roll along the surface of the ground |
| What are the four factors promoting erosion by wind? | non cohesive soil; loose, small particles; land (vegetation) cover is sparse; higher wind speeds |
| What are the two factors minimizing erosion by wind? | moist, dense soil; high vegetation cover |
| What is soil moisture? | the quantity of water contained in a soil material; promotes cohesiveness of aggregates |
| What is soil shear strength? | the amount of effort required to shear soul particles apart |
| What is the WEQ? | E = C x K x I x LV TONS/ACRE/YEAR; C – climate factor, K – surface roughness factor, I – erodibility factor, LV – length of field, vegetation cover factor |
| What are the two factors of the WEQ that cannot be managed? | climate factor C, erodibility factor I |
| What three factors can be managed? | Length of field L, vegetation cover V, surface roughness K |
| Can careful management allow for changes of erodibility factor (increase in humus over long periods of time) to help combat wind erosion? | yes |
| How does length of field factor combat wind erosion? | decrease the field width and lengths with buffer strips (wind breaks); wind breaks decrease wind speeds, catch suspended solids and prevents creep. |
| True or False: Paths should pass through windbreaks at angles. | true |
| How does the management strategy vegetation cover combat wind erosion? | vegetation slows down wind speed, creates soil clouds around roots; value depends on amount of cover, coarse/fine, standing height, living or dead |
| How does the management strategy surface roughness combat wind erosion? | rough surface prevent displacement of particles; breaks up wind path; can be altered with tillage practices (introduce ridges) |
| What is distance of ridges that effectively reduce erosion and trap soil? | 5 – 10 cm |
| What are four impacts of wind erosion? | poor air quality, decreases surface water quality, loss of arable land |
| Rainwater naturally picks up dissolved carbon dioxide from the environment; this becomes __________ solution. Acid rain is created by human added atmospheric sulfur and nitrogen. | a weak carbonic acid solution |
| _________ is a chemical weathering process affecting silicate and carbonate minerals. It is a chemical process in which a _______ molecule is added to a substance resulting in the split of that substance into two parts. | Hydrolysis, water EX. Hydrolysis of feldspar to form clay. |
| __________ leads to rust. | oxidation. |
| Salt crystallization, otherwise known as ______ causes disintegration of rocks when saline solutions seep into cracks -> evaporation -> leaving salt crystals behind that will expand when heated and this causes pressure on the confining rock. | Haloclasty |
| How do trees act as biological eroders? | penetration of the roots into the small cracks of rocks, eventually can wedge the rock apart. |
| In 2006 80% of Canadians lived in an URBAN area. TREND: 2% increase every 10 years | |
| Total deforestation from 1989 to 1999 was 43 430 ha; 41% drop in all forest types | |
| What are some of the effects of urbanization and increasing impervious areas? | decreased infiltration, increased water flows, rapid redirection of flow (storm drains), loss of vegetation and natural filtration systems, decreased groundwater recharge, increased pollutant levels in water courses. |
| The effects of urbanization combine to increase flooding, increased pollution, and __________________ which increases rate of erosion. | increased water speed on our waterways |
| ____ of the Sturgeon Lake Watershed is agriculture. | 53% |
| _______ of streams flow into Lake Simcoe. | 35 rivers, total 4000 km of streams |
| Target P loading into Lake Simcoe? | 44 tons/yr (2007 – 71.5 – 77.3 ton/yr) |
| What is one source of phosphorous from urbanization? | stormwater runoff carrying contaminants (ex. Dirt, oil, salt, fertilizers, pet waste and detergents) |
| What are two main sources of phosphorous in the Lake Simcoe? | tributaries (urban and non urban – agric.) and atmospheric deposition (originated at local sources) |
| The health of coldwater fish community, especially ___________ is a good indicator of environmental quality and the overall health of the aquatic ecosystem. | lake trout |
| Severe _________ of spawning shoals can smother and reduce survival of eggs ; __________ of rocky spawning substrates also makes deposited eggs more vulnerable to predators such as crayfish and mottled sculpins. | sedimentation; infilling |
| True of False: Suspended sediments can clog gills of fish and inverts. and impact their ability to navigate predators and find food. | True |
| What is the innovation called that can help to reduce P levels. | phoslock |
| How do effectively manage erosion and sediment control (dealing with construction)? | multi barrier approach |
| Erosion Control Measure – What is a vegetative filter (buffer) strip? | use existing vegetation around sites to slow sheet water runoff, simple; 30 m buffer for cold water stream, 15 m for warm water stream |
| What are three applications of SEEDING which is low cost and establishing plant cover? | mechanical, terraseeding (computer calibrated soil with seed), hydroseeding, sodding. |
| What are some examples of NATURAL COVER for erosion control? | mulching, planting, rootwads, logs, straw |
| True or False: Scarificiation is a method of erosion control. | true, surface roughening to combat surface creep |
| What are some of the requirements and benefits of using GEOTEXTILES? | can be preseeded, must remove debris, must ensure good contact with the soil, staked and overlapped at edges |
| Sediment Control Measure? | used to limit the amount of suspended soils from leaving a construction site, 3 sections: perimeter, settling and filtration controls. |
| Examples of Sediment Control Measures? | siltsoxx, filtersoxx, control fences, vehicle tracking wash rack, temporary diversions, basins/traps, control ponds (long term) |
| What are some of the engineering tools used in Drainageway Protection? | stream diversions, curb inlet protection, drop inlet protection, filter rings, inlet sox, drainage bags |
| What are the assumptions of the rational method for estimation of peak run off during a rain event? | max rate of flow is produced by a constant rainfall; rainfall is uniform in space over drainage area; storm duration associated with the peak flow rate is equal to the rainfall intensity. |
| What is required for the rational method, Q = 0.0027 CiA | Q = peak rate of runoff (m3/sec); C = coeff. Of proportion of rainfall to enter watercourse as runoff; I = avg. rainfall intensity (mm/hr) A = area of watershed basin (ha) |
| What is the general rule for stream flooding? | a 3 hour rainfall total exceeding the 10 – year return period is likely to cause flooding. |
| What is the time of concentration (TC)? | calculates the length of time for rain at the head of the watershed to arrive at the terminus as runoff. |
| What is required for the TC calculation, TC = 0.0196 (L)1.1555/H0.385? | TC = minutes, L = max. travel length (m), H = change of elevation in travel length (m), volume = Q x TC (need TC in seconds) |
| What is bioengineering? | the use of plants and plant products as engineering materials. |
| ______________ are transitional areas between water and land, ecotones rich with elements of both. __________ is a key element that has numerous functions. | Riparian zones, vegetation |
| Why are plants so important to erosion control - hydrologically? | interception on foliage (reduce splash erosion), infiltration capacity increased due to higher ground surface roughness and permeability, transpiration of water-uptake by roots lowers pore – water pressure,cracking of soil due to transpiration |
| Why are plants so important to erosion control – mechanically? | soil reinforcement by roots (increase shear strength), anchoring of topsoil into firm strata, increase normal and downhill forces, |
| Why are plants so important to erosion control – technical advantages? | protection against surface erosion, increase in slope stability by root reinforcement and draining, protect against rock fall and wind |
| Why are plants so important to erosion control – ecological advantages? | regulation of temperature and humidity close to the surface – promoting growth; improvement of the soil water regime via interception, evapotranspiration and storage; soil improvement and top soil formation; promote habitat formation |
| Examples of bioengineering techniques? | live stakes, wattles/fascines, brush layering, palisades, shade creation, live ground sills (creates small steps on low grades), rootwads, live rock/boulder revetments, brush mattresses, and more |
| What is consideration to remember when working with live rock, boulder revetments? | needs to be used sparingly; will provide immediate results but can lead to speeding up the water. |
| What are some of the limitations when implementing bioengineering techniques? | time, labour intensive, planting times, slope needs to be able to support growth, can be slow to establish, maintenance and monitoring, |
Created by:
envirolife
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