III. Soil and Water Conservation Engineering (30%) Flashcards
- Slope of the upstream face of the embankment.
A. Downstream slope
B. Outside slope
C. Inside slope
D. Upstream slope
Answer: C
- Inside bottom or sill of the conduit.
A. Invert
B. Inside base
C. Inside sill
D. Bottom sill
Answer: A
- 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
Answer: D
- __________ 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
Answer: A
- _________ 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
Answer: D
- Spacing between irrigation laterals.
A. Ditch spacing
B. Lateral spacing
C. Horizontal spacing
D. Irrigation spacing
Answer: B
- 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
Answer: C
- 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
Answer: B
- 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. Wastewater limit
Answer: B
- Portion of the pipe network between the mainline and the laterals.
A. Diversion pipe
B. Manifold
C. Main-lateral pipe
D. Reducer
Answer: B
- 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
Answer: C
- 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
Answer: D
- 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
Answer: A
- 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
Answer: D
- In what condition is the open channel freeboard used for water conveyance?
A. Maximum flow
B. Emergency flow
C. Inundation
D. Rainy days
Answer: C
- 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
Answer: B
- 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
Answer: B
- Part of the system that impounds the runoff.
A. Storage
B. Reservoir
C. Impounding
D. Runoff collector
Answer: B
- Slope at the downstream face of the embankment.
A. Outside slope
B. Inside slope
C. Side slope
D. Soil gradient
Answer: A
- 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
Answer: A
- 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
Answer: C
- 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
Answer: B
- Vertical flow of water to carry salts contained in water.
A. Leaching
B. Percolation
C. Infiltration
D. Seepage
Answer: A
- 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
Answer: A
- The process by which the soil is removed from its natural place.
A. Soil removal
B. Runoff
C. Soil erosion
D. Leaching
Answer: C
- 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
Answer: B
- The practice where legumes are plowed or incorporated into the soil.
A. Legume incorporation
B. Legume manuring
C. Green manuring
D. Manuring
Answer: C
- Farming practice where plowing and harrowing are done along the contour.
A. Contouring
B. Strip cropping
C. Crop row aligning
D. Contour plowing
Answer: A
- 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
Answer: D
- Advanced form of erosion.
A. Rill erosion
B. Gully erosion
C. Sheet erosion
D. Advanced erosion
Answer: B
- Dam which resists water flow of water by its weight.
A. Resisting dam
B. Buttress dam
C. Gravity dam
D. Arc dam
Answer: C
- Dam consisting of stones enclosed in cyclone wires which allows water passage.
A. Gabion dam
B. Stone dam
C. Cyclone dam
D. Interlink dam
Answer: A
- Material used to cover the soil to minimize evapotranspiration.
A. Plastic
B. Mulch
C. Leaves
D. Soil cover
Answer: B
- Geological formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rocks such as limestone dolomite.
A. Geological layer
B. Dissolved layer
D. Soluble layer
D. Karst topography
Answer: D
- Scientific name of carabao grass commonly used in vegetated open channels.
A. Glerisedia sepium
B. Paspalum conjugatum
C. Cyperus rotundos
D. Leucaena leucocepala
Answer: B
- Philippine geographical constant for determining terrace vertical interval.
A. 0.5
B. 0.8
C. 1
D. 1.5
Answer: A
- Constant for soil erodibility and cover conditions for erodible soil and poor cover.
A. 0.5
B. 0.8
C. 1
D. 1.5
Answer: C
- Estimate the peak runoff rate from a 20-hectare drainage basin if rainfall depth for 6 hours reached 60 mm. Use typical runoff coefficient of 0.35.
A. 2 cms
B. 0.02 cms
C. 0.2 cms
D. 2.2 cms
Answer: C
Solution:
I = 60 mm/6 hrs = 10 mm/hr
q = 0.0028 CIA = 0.0028 (0.35)(10 mm/hr)(20 has) = 0.2 cms
- Estimate the runoff volume from a 20-hectare drainage basin if rainfall depth for 6 hours reached 60 mm and duration of runoff is about 3 hours. Use typical runoff coefficient of 0.35.
A. 1,080 cms
B. 1,800 cms
C. 1,008 cms
D. 8,100 cms
Answer: A
Solution:
I = 60 mm/6 hrs = 10 mm/hr q = 0.0028
CIA = 0.0028 (0.35)(10 mm/hr)(20 has)=0.2 cms
Q = 0.5qT = 0.5 (0.2 cms) (3 hrs) (3600 s/hr)
= 1,080 cms
Difficult Questions
- A trapezoidal concrete gravity dam has vertical upstream wall. Water depth in the upstream side is 50 meters above the dam base. Freeboard of 15% based on design depth. What is the force of water exerted against dam per meter of dam width at deepest section?
A. 1,100 tonnes
B. 1,150 tonnes
C. 1,200 tonnes
D. 1,250 tonnes
Answer: D
Solution:
P = 0.5 x Water density x H2 = 0.5 x1 tonne/m3
x (50 m)2 = 1,250 tonnes
- A trapezoidal concrete gravity dam has vertical upstream wall. Water depth in the upstream side is 50 meters above the dam base. The base of dam is 78 meters along water flow. What is the uplift force of seepage water below the dam per meter of dam width at deepest section?
A. 1,900 tonnes
B. 1,950 tonnes
C. 2,000 tonnes
D. 2,050 tonnes
Answer: B
Solution:
U = 0.5 x Water density x H x B = 0.5 x 1 tonne/m3
x 50m x 78m = 1,950 tonnes
- A trapezoidal concrete gravity dam has inclined upstream wall. Resisting moment relative to the dam toe is 263,953.2 tonne-meters while overturning moment is 96,233.3 tonne-meters per meter of dam width at deepest section. What is the safety factor against overturning? Is it
safe?
A. 0.36, unsafe
B. 2.74, safe
C. 3. 96, safe
D. 5.48, excessively safe
Answer: B
Solution:
FSo = RM/OM = 263953.2/96233.3 = 2.74
