Soil and Water Conservation Engineering Flashcards
Slope of the upstream face of the embankment.
A. Downstream slope
B. Outside slope
C. Inside slope
D. Upstream slope
C. Inside slope
Inside bottom or sill of the conduit.
A. Invert
B. Inside base
C. Inside sill
D. Bottom sill
A. Invert
Closed conduit designed to convey canal water in full and under pressure running condition, to convey canal water by gravity under roadways, railways, drainage channels and local depressions.
A. Close siphon
B. Pressurized conduit
C. Siphon
D. Inverted siphon
D. Inverted siphon
_______ water requirement is the amount of water required in lowland rice production which includes water losses through evaporation, seepage, percolation and land soaking.
A. Land preparation
B. Irrigation
C. Crop
D. Field
A. Land preparation
_________ water requirement is the amount of water required in lowland rice production which is a function of the initial soil moisture and the physical properties of the soil.
A. Land preparation
B. Irrigation
C. Crop
D. Land soaking
D. Land soaking
Spacing between irrigation laterals.
A. Ditch spacing
B. Lateral spacing
C. Horizontal spacing
D. Irrigation spacing
B. Lateral spacing
Deep percolation of water beyond the root zone of plants, resulting in loss of salts or nutrients.
A. Vertical percolation
B. Root zone percolation
C. Leaching
D. Salt leaching
C. Leaching
Canal with impermeable material (usually concrete) for channel stabilization and/or reduced seepage.
A. Line canal
B. Lined canal
C. Unlined canal
D. Impermeable canal
B. Lined canal
Allowable pollutant-loading limit per unit of time, which the wastewater generator is permitted to discharge into any receiving body of water or land.
A. Pollutant limit
B. Loading limit
C. Allowable limit
D. Waste limit
B. Loading limit
Portion of the pipe network between the mainline and the laterals.
A. Diversion pipe
B. Manifold
C. Main-lateral pipe
D. Reducer
B. Manifold
Spillway which is not excavated such as natural draw, saddle or drainage way.
A. Surface spillway
B. Flood spillway
C. Natural spillway
D. Earth spillway
C. Natural spillway
Constant flow depth along a longitudinal section of a channel under a uniform flow condition.
A. Critical depth
B. Constant depth
C. Laminar depth
D. Normal depth
D. Normal depth
Maximum elevation of the water surface which can be attained by the spillway-type dam or reservoir without flow in the spillway.
A. Normal storage
B. Maximum storage
C. Critical elevation
D. Design depth
A. Normal storage
Maximum elevation of the water surface which can be attained in an open channel without reaching the freeboard.
A. Normal storage
B. Maximum storage
C. Critical elevation
D. Design depth
D. Design depth
In what condition is the open channel freeboard used for water conveyance?
A. Maximum flow
B. Emergency flow
C. Inundation
D. Rainy days
C. Inundation
The primary purpose in limiting water flow not to go below minimum velocity.
A. Avoid percolation
B. Avoid sedimentation
C. Avoid critical depth
D. Optimize flow
B. Avoid sedimentation
Open channel flow is water flow that is conveyed in such a manner that top surface is exposed to the atmosphere such as flow in canals, ditches, drainage channels, culverts, and pipes under _____ flow conditions
A. Full
B. Partially full
C. Normal
D. Critical
B. Partially full
Part of the system that impounds the runoff.
A. Storage
B. Reservoir
C. Impounding
D. Runoff collector
B. Reservoir
Slope at the downstream face of the embankment
A. Outside slope
B. Inside slope
C. Side slope
D. Soil gradient
A. Outside slope
Ratio between reference evapotranspiration and water loss by evaporation from an open water surface of a pan.
A. Pan coefficient
B. Evaporation ratio
C. Reference pan ratio
D. ET ratio
A. Pan coefficient
Rate of water loss by evaporation from an open water surface of a pan.
A. Surface evaporation
B. Sunken evaporation
C. Pan evaporation
D. Evaporation loss
C. Pan evaporation
Vertical flow of water below the root zone which is affected by soil structure, texture, bulk density, mineralogy, organic matter content, salt type and concentration.
A. Leaching
B. Percolation
C. Infiltration
D. Seepage
B. Percolation
Vertical flow of water to carry salts contained in water.
A. Leaching
B. Percolation
C. Infiltration
D. Seepage
A. Leaching
Method to determine the rate of flow under laminar flow conditions through a unit cross sectional area of soil under unit hydraulic gradient.
A. Permeability test
B. Laminar test
C. Flow test
D. Hydraulic test
A. Permeability test
The process by which the soil is removed from its natural place.
A. Soil removal
B. Runoff
C. Soil erosion
D. Leaching
C. Soil erosion
A kind of terrace which consists of a series of flattened areas.
A. Broad-base terrace
B. Bench terrace
C. Conservation terrace
D. Rice terrace
B. Bench terrace
The practice where legumes are plowed or incorporated into the soil.
A. Legume incorporation
B. Legume maturing
C. Green manuring
D. Manuring
C. Green manuring
Farming practice where plowing and harrowing are done along the contour.
A. Contouring
B. Strip cropping
C. Crop row aligning
D. Contour plowing
A. Contouring
The simplest method of determining soil erosion over a period of time.
A. Catchment method
B. Erometer method
C. Plumb bob method
D. Pin method
D. Pin method
Advance form of erosion.
A. Rill erosion
B. Gully erosion
C. Sheet erosion
D. Advanced erosion
B. Gully erosion
Dam which resists water flow of water by its weight.
A. Resisting dam
B. Buttress dam
C. Gravity dam
D. Arc dam
C. Gravity dam
Dam consisting of stones enclosed in cyclone wires which allows water passage.
A. Gabion dam
B. Stone dam
C. Cyclone dam
D. Interlink dam
A. Gabion dam
Material used to cover the soil to minimize evapotranspiration.
A. Plastic
B. Mulch
C. Leaves
D. Soil cover
B. Mulch
Geological formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rocks such as limestone or dolomite.
A. Geological layer
B. Dissolved layer
C. Soluble layer
D. Karst topography
D. Karst topography
Scientific name of carabao grass commonly used in vegetated open channels.
A. Glerisedia sepium
B. Paspalum conjagatum
C. Cyperus rotundos
D. Leucaena leucocepala
B. Paspalum conjagatum
Philippine geographical constant for determining terrace vertical interval.
A. 0.5
B. 0.8
C. 1
D. 1.5
A. 0.5
Constant for soil erodibility and cover conditions for erodible soil and poor cover.
A. 0.5
B. 0.8
C. 1
D. 1.5
C. 1
Estimate the peak runoff rate in cubic meters per second from a 20-hectare drainage basin if rainfall depth for 6 hours reach 60 mm. Use typical runoff coefficient of 0.35.
A. 2
B. 0.02
C. 0.2
D. 2.2
C. 0.2
Determining rainfall intensity I
I = 60 mm/6 hours = 10 mm/hr
Determining Peak Runoff Rate, q
q = 0.0028CIA
q = 0.0028(0.35)(10 mm/hr)(20 has) = 0.2 m3/s
Estimate the runoff volume in cubic meters from a 20-hectare drainage basin if rainfall depth for 6 hours reach 60 mm and duration of runoff is about 3 hours. Use typical runoff coefficient of 0.35.
A. 1080
B. 1800
C. 1008
D. 8100
A. 1080
Determining rainfall intensity I
I = 60 mm/6 hours = 10 mm/hr
Determining Peak Runoff Rate, q
q = 0.0028CIA
q = 0.0028(0.35)(10 mm/hr)(20 has) = 0.2 m3/s
Determining Total Runoff Volume, Q
Q = 0.5 x Peak runoff rate x Duration
Q = 0.5qT
Q = 0.5(0.2 cu.m/s)(3 hrs x 3600 s/hr)
Q = 1080 cubic meters
These results from the impact of water drops directly on soil particles or on thin water surfaces.
RAINDROP OR SPLASH EROSION
the upper part of the soil is washed away in a uniform thin layer from sloping lands, resulting to sheet or overland flow.
SHEET EROSION
The removal of soil by water from small but well – defined channels or streamlets. Rill is small enough to be easily removed by normal tillage operations. It is the form on which most soil erosion occurs.
RILL EROSION
Is an advance form of rill erosion. It produces channels larger than rills that cannot be erased by tillage.
GULLY EROSION
Consist of soil removal from banks of streams or rivers. The water cuts the lower banks causing the upper parts to fall.
STEAM CHANNEL EROSION
Are channel sodded with grasses, which absorbs the energy of run – off.
CONSTRUCTION OF VEGETATED WATERWAYS
Is a method of erosion control accomplished by constructing board channel or benches across the slope. Terraces control erosion by reducing the slope length.
TERRACING
Consist of a series of flattened areas that are converted steep slope of 20 to 30 % to a series of level benches.
BENCH TERRACE
The primary purpose of this type of terrace is to remove excess water to minimize erosion. The intercepted runoff is conducted to a safe outlet at a lower velocity
GRADED OR CHANNEL TYPE TERRACE
The primary purpose for this type of terrace is moisture conservation. It intercepts and detains runoff to be stored in the soil profile.
LEVEL OR RIDGE-TYPE TERRACE
Field operation such as plowing, harrowing, planting, cultivating, and harvesting are performed approximately on the contour.
CONTOURTING OR CONTOUR FRAMING
Is the process of growing alternate strips of different crops in the same field.
STRIP CROPPING
The layout and tillage are closely to the exact contour and with the crops following a definite rotational sequence.
CONTOUR STRIP CROPPING
Strip of uniform width is placed across the general slope.
FIELD STRIP CROPPING
Strips of closely growing plants, usually grass or legumes, are laid to out between contour strips of crops in regular rotations.
BUFFER STRIP CROPPING
A practice where adjoining farms operate as a single unit.
COMPACT FARMING
Planting closely growing crops such as grass and legumes.
COVER CROPPING
The systematic planting of different crops in succession. Generally, a leguminous crop should follow a grain crop; a deep-rooted crop should follow a shallow rooted crop.
CROP ROTATION OR RELAY CROPPING
A practice where legumes are plowed and incorporated with the soil during the flowering stage to improve the soil structure, increase the filtration capacity and provide nutrients for plants.
GREEN MANURING
Application of the tillage necessary to produce crops. Most parts of the field are left undisturbed and compact to give greater resistance for the field against erosion
MINIMUM TILLAGE
Planting different crops simultaneously in the same field at the same cropping season.
MULTIPLE CROPPING OR MIXED CROPPING
Is a multiple cropping system where different crops are grown at alternative rows.
INTERCROPPING
Aims to break –up hard pans, either natural ones or those developed by continuous plowing at the same depth, to improve infiltration.
SUBSOILING OR SUB – SURFACE TILLAGE
An instrument to measure the depth and intensity of rain falling or a flat surface.
RAIN GAGE
Refers to the depth of rainfall over an area per unit time.
RAINFALL INTENSITY
Type of rain gage which measures rain depth and intensity.
RECORDING RAIN GAGE
Type of rain gage which measures rain depth only. Rain gages of this type are generally vertical, cylindrical containers with top opening 203mm(8 in.) in diameter. The water is funneled into an inner cylinder one-tenth of the cross section of the catch area or collector.
NON – RECORDING RAIN GAGE
The average periods of time, which the depth of rainfall for a given duration will be equaled or exceeded once on the average.
RETURN PERIOD OR RECURRENCE INTERVAL
This can be computed by summing all the rainfall observations divided by the number of observations
AVERAGE DEPTH OR ARITHMETIC
Location of the rain gages plotted on a map of the watershed and straight lines are drowning between the rain gages. Perpendicular bisectors are then constructed on these connecting lines such that the bisectors form on an enclosed referred to as Thiessen polygon. The rain recorded is then considered to represent the precipitation within the appropriate polygon area.
THIESSENS METHOD
This involves the plotting of isohyets or lines of equal rainfall.
ISOHYETAL METHOD
Is that portion of the precipitation that makes its way forward stream channels, lakes or oceans as surface flow.
RUNOFF
Is defined as the application of water to soil for the purpose of supplying the moisture essential for plant growth.
IRRIGATION
Refers to the weight of a unit volume of dry soil in its natural structural condition.
BULK DENSITY
Is the ratio of the weight of a given volume of dry soil, airspace included, to the weight of an equal volume of water. It is also the ratio of the bulk density to the density of water.
APPARENT SPECIFIC GRAVITY
Is the weight per unit volume of the soil particle.
PARTICLE DENSITY
Is the ratio of the density of a single soil particle to the density of water.
REAL SPECIFIC GRAVITY
Is a thin film of water on the surface of the soil grains and is not capable of significant movement by the action of gravity or capillary forces.
HYGROSCOPIC WATER
Is that parts in excess of the hydroscopic water, which exist in the pore space of the soil and is retained against the force of gravity
CAPILLARY WATER
Water that moves downward freely by the action of gravity.
GRAVITATIONAL WATER
Is the moisture content of the soil when the gravitational water has been removed. It is usually determined two days after irrigation or heavy rainfall.
FIELD CAPACITY
The soil moisture content when plants permanently wilt. A plant is considered to be permanently wilted when it will not revive if placed in a saturated Condition
PERMANENT WILTING POINT OR WILTING COEFFICIENT
The range in moisture content between filed capacity and wilting point. It represents the amount of water that can be retained in the soil for the use by the crop.
AVAILABLE MOISTURE
Refers to the percentage of the available moisture to which the moisture content is allowed to reach before the next irrigation is applied.
ALLOWABLE DEFICIT
Determines the depth of soil necessary to be welted during irrigation. Water application beyond the root zone result to water loss due to deep percolation while shallow application inhibits full development of the root system.
ROOTZONE DEPTH
Refers to the number of days between two irrigation applications. It is also the number of days after irrigation when the moisture content reaches the allowable depletion level.
IRRIGATION INTERVAL OR FREQUENCY
The number of hour’s irrigation water is applied. It is influence by the filtration capacity of the soil.
IRRIGATION PERIOD
Refers to the sum of the water requirement and losses due to the inefficiency of the irrigation system.
NET WATER REQUIREMENT OR NET APPLICATION DEPTH
Water content of the soil is measured by oven drying the soil samples 150OC until there is no further change in weight. Time of drying is at least 24 hours.
GRAVIMETRIC METHOD
This rapid means of onsite moisture measurement.
NEUTRON SCATTERING
Is an instrument used to describe the moisture status of the soil in terms of its suction.
TENSIOMETER
This is a method employed only by the experienced irrigators. The irrigators observe the moisture of the soil by pressing a soil sample with his fingers.
FEEL AND APPEARANCE METHOD
These are used in places where the natural ground to where the canal will be laid out is very steep. If the canal profile follows the canal ground, the water velocity could be very high. The energy of the following stream is dissipated in the stilling basin or apron of drops.
DROPS OR DROPS SPILLWAYS
These are structures which are used to convey water down relatively steep hills which would require many drops closely spaced to control water velocity.
CHUTES
Is an elevated section of an irrigation canal. It is used for crossing natural depressions like creeks or rivers.
FLUME
Conveys water over the ditch bank into the field or furrow.
SIPHON TUBE
These are pipelines build on or near the ground surface. This structure conveys water across wide depressions.
INVERTED SIPHONS
This is done introducing water and letting it spread over the area to be irrigates. Water is applied from ditches without any levees to guide its flows or restrict its movement. This irrigation method is suited in place where water is abundant and inexpensive
UNCONTROLLED OR WILD FLOODING
Is done by subdividing the field into a series of strips, 5 to 20 meters wide and 75 to 100 meters long by levees or borders. Two adjacent borders guide advancing water. Strips are usually oriented to run down the predominant slope through some are built on the contour.
BORDER STRIP FLOODING
Consist of supplying large flow into relatively level plots surrounded by levees or dikes. This method is suited to prevent high percolation losses in areas with highly permeable soils.
LEVEL BORDER OR CHECK FLOODING
Like the level border, the area irrigated by this method is surrounded by levees. It is useful on fine texture soils with low permeability where it is necessary to maintain standing water to secure adequate penetration.
BASIN FLOODING
Requires the forming of small channel known as furrows where the irrigation water runs through. Irrigation by furrow wets only a portion of the ground surface, thus, reducing evaporation.
FURROW IRRIGATION
It is a variation of the furrow method and makes use of small and shallow furrow of rills called corrugation.
CORRUGATION IRRIGATION
Application of irrigation water is done in much the same way as rain. With this method, not only the soil is wetted but also the stem and leaves of the plants
OVERHEAD IRRIGATION
is the simplest overhead irrigation equipment commonly used in backyard gardening. It is provided with a thin cylinder stem with a perforated part on the end to allow rainfall simulation
WATERING CAN
This is done in place where there is a piped water system. A hosepipe is connected to an outlet or faucet, which conveys water to the crops.
HOSE PIPE
Consist of applying water to the surface of the soil in form of spray, which closely resembles that of rain. The flow water under pressure through small opening or nozzles produces the spray.
SPRINKLER IRRIGATION
Is a method of applying water directly to the soil near the plant through a network of small diameter pipes. The pipes provided with low flow rate outlets called emitters of drippers.
DRIP OR TRICKLE IRRIGATION
The depth of water in mm or inches to be removed in a 24-hour period from the drainage area, (in mm/day or in/say)
DRAINAGE COEFFICIENT
Specific property of soil is measure of the readiness with which the soil transmits water. Permeability is a velocity and for agricultural purposes can be conveniently expressed either in inches/hour or cm/hour.
Permeability
The downward movement of water into the soil through the soil surface, and the rate is generally expressed in in/hr or mm/hr.
Infiltration
Refers to the passage of soil water through the plant system, principally the leaves and its vaporization into the atmosphere.
Transpiration
Structured device designed to hold a pool of water to cushion the impact and retard the flow of falling as from overflow weir, chute, or drop.
Stilling Basin
a principle of English Common Law, which recognizes the right of riparian owner to make reasonable use of the stream flow provided the water, is used on riparian land.
Riparian Right
is that which is contiguous to a stream or body of water surface.
Riparian Land
type of drain whereby channels are produced by a tractor – drawn shaped metal in a subsoil without a trench from the surface.
Mole drain
consist of growing alternate strips of clean cultivated and close – growing crops in the same field.
Strip Cropping
planting different crops simultaneously in the same field at the same cropping season
Multiple Cropping or mixed cropping
(crop rotation) planting different crops, one after each season.
Relay Cropping
Is a gate placed across a stream from which it is desired to divert water. The function of the check gate is analogous to that of the dam of the diversion weir or the rivers at the heads of canal systems.
Check gates
Used to divert from a project canal into the farm delivery systems or from a man canal into lateral canals.
Head gates
Specially shaped and stabilized channel section, which may also be used to measure flow and is generally less inclined to catch floating debris and sediments than a weir.
Flume
Closed conduit usually circular, square or rectangular in cross section, used for conveying water across and under an elevated roadway, embankments or dikes.
Culvert
The ratio of depth of direct run – off to depth precipitation producing the runoff over a drainage area.
Run-off coefficient
An irrigation method which necessitates the welting of only part of the surface (from ½ to 1/5) thus reducing evaporation losses, lessening the pudding of heavy soils, and making it possible to cultivate the soil sooner after irrigation.
Furrow Irrigation
An irrigation that makes use of small, shallow furrows.
Corrugation
