PART II Flashcards
Soil and Water Conservation Engineering, Farm Irrigation and drainage, and allied subjects
The application of engineering and biological principles to the solution of soil and water management problems
Soil and Water Conservation Engineering
utilization of resources without or minimal waste
Conservation
maintaining the quality unchanged
Preservation
Total land area of the Philippines
300,00 km^2 or 30M ha
what does BSWM mean?
Bureau of Soil and Water Management
This bureau is under DA and is assigned to implement projects like development of small-scale irrigation projects
BSWM (Bureau of Soil and Water Management)
In charge of large irrigation projects (NIS, CIS, PIS)
NIA
Irrigation efficiency of the Philippines according to World Bank
39.13%
estimated hectarage of arable land
4.6 Mha
The detachment and transport of soil particles by natural or anthropogenic causes
Soil erosion
the susceptibility of the soil to be eroded
Soil erodibility
The capacity of rainfall to cause erosion
rainfall erosivity
The uniform removal of soil in thin layers from sloping land, resulting from sheet or overland flow
Sheet erosion
The splash and sheet erosion combined
Interill erosion
the detachment of soil by a concentrated flow of water
Rill erosion
produces channel larger than rills, and which cannot be obliterated by normal tillage
Gully erosion
consists of soil removal from stream banks or soil movement in channel
Streambank erosion
Classification of gully erosion: less than or equal to 1m gully depth and less than or equal to 2ha drainage area
Small
Classification of gully erosion: 1-5m gully depth and 2-20ha drainage area
Medium
Classification of gully erosion: greater than 5m gully depth and greater than 20ha drainage area
Large
Arrange the stages
I. Healing stage
II. Channel erosion by downward scour of topsoil
III. Upward movement of gully head and enlargement of gully width
IV. Stabilization stage
A.I, II, III, IV
B. IV, III, II, I
C. II, III, I, IV
D. II, III, IV, I
C
Fraction of sheet and rill erosion that actually reaches the reference point of discharge
Sediment Delivery Ratio
Planting along contours or land surface with the same elevation
Contouring
alternate planting of 2 or more different crops along contour
Strip cropping
placement of crop residues, plastic, or other synthetic materials around the base plant or throughout the field to reduce evaporation from land surface
Mulching
grasses and other erosion-retarding vegetation planted alternatively with rows of crops, along contours
Hedgegrows and grass boundary
alternate planting of different crops on successive planting seasons
Crop rotation
structure across a stream to control or divert the flow, measures the flow of water
Weir
water conveyance and control structure with considerable slope, conveying water from a higher to a lower elevation
Chute
Water conveyance and control structure with a 90 degree water drop
Drop spillway
Water conveyance and control structure with water inlet mechanism
Drop inlet
natural or artificial channel that shortens a meandering stream. The purpose of this is to increase the velocity, to shorten the channel length and to decrease the length of levees
Cut-offs
A synthetic permeable textile material used with soil, rock or any other geotechnical engineering related material
Geotextile
Annual soil erosion rate formula
E=RKLSCP ,
Annual soil erosion= rainfall and runoff erosivity factor *Soil erodibility factor *Slope length factor *slope gradient factor *cover and crop management factor *erosion control practices or conservation practice factor`
Entrainment of solid material into a water body of channel and its further effects and consequences
Sediment Transport
process of deposition of sediment to downstream location
Sedimentation
rate of sediment flow
Sediment Load or discharge
Sediment or soil particles suspended in the water body and has more harmful effect due to its higher transportability
Suspended Load
Sediment near or few inches from the stream bed and move by crawling or sliding
Bed load
Sediment transported by saltation or jumping
Saltation
Is a conduit in which a liquid flows with a free surface
Open channel
Flow having a free surface and subjected to atmospheric pressure
open channel flow
Flow confined in a closed conduit, has no free surface and exerts no direct pressure but hydraulic pressure only
Pipe flow
Continuity equation Q=V1A1= V2=A2. Energy grade line, hydraulic grade line, and channel bed are _____, the flow is uniform
parallel
Depth of flow does not change or if it can be assumed to be constant during the time interval under consideration
Steady flow
usually a long and mild-sloped channel built in the ground which maybe line or unlined
Canal
is a channel made of wood, metal or concrete supported above the surface of the ground to carry water across a depression
Flume
channel having a steep slope
Chute
Similar to chute, but the charge in elevation is effected in a short distance
Drop
A covered channel or comparatively short length installed to drain water through a highway and railroad embankments
Culvert
Comparatively long covered channel used to carry water through a hill or any obstruction on the ground
Open-Channel tunnel
A channel built with uniform cross-section and constant bottom slope
Prismatic Channel
The vertical distance of the lowest point of the channel section from the free surface
Depth flow
The elevation or vertical distance of the free surface above a datum
Stage
The width of the channel section at the free surface
Top width
The cross-sectional area of the flow normal to the direction of the flow
water area
The length of the line of intersection of the channel wetted surface with a cross-sectional plane normal to the direction of flow
Wetted perimeter
ratio of water area to its wetted perimeter
Hydraulic radius
ratio of the water area and the top width
Hydraulic depth
What is the unit value of E when the rainfall kinetic energy formula is E=0.119+0.0873(logI)? (I=___/hr)
MJ/ha-mm
the unit value of E when the rainfall kinetic energy formula is E=210.3+89(logI) (I=___/hr)
MT/ha-cm
the unit value of E when the rainfall kinetic energy formula is E=916+331(logI) (I=___/hr)
ft-tons/acre-in
The depth, water area, velocity, and discharge at every section of channel reach are constant
Uniform flow
The energy line, water surface, and channel bottom are all parallel, that is, their slope are equal
Uniform flow
Formula generally used in open channel conditions
Manning’s formula (V=Cm.R^0.67.S^0.5)
Define the values of the Manning’s formula variables
V= velocity of the flow, Cm=Conversion factor which is 1..49 for English units, and 1.0 for metric units, R=hydraulic radius which is equal to A/P, and S=Slope
These are lined and built-up channels which can withstand erosion satisfactorily. Lining material maybe stone masonry, steel, cast iron, timber, glass and plastic
Non-erodible channel
It is the velocity that will not start sedimentation and will not include the growth of aquatic plants and moss
Minimum permissible velocity or the non-silting velocity
The vertical distance from the top of the channel to the water surface at the design condition. It is provided to prevent waves or fluctuations in water surface from overflowing the sides
Freebpard
The Manning coefficient of roughness for grassed channels is specifically known as
retardance coefficient
the total land area that contributes to the flow of a particular water body and drains to a common outlet
watershed
The divide between two areas drained by different river systems
watershed
natural drainage areas within the boundary defined by the watershed divide
Catchment and basins
a region drained by a large river system, implying a very large watershed or catchment
River basin
The process of guiding and organizing land and other resources uses in a watershed to provide desired goods and services without adversely affecting soil and water resources
Watershed Management
an inundation or overflow from river or other body of water, excess amount of water level in a stream channel above its capacity to carry or handle
flood
low lying areas which are frequently flooded
flood plain
The reduction of flood hazards and the ensuing damage to any given region of a flood plain to a minimum, consistent to the cost involved
Flood protection or flood damage mitigation
floods that occur from storms of low intensity having a duration of a few days to several weeks
large-area floods
floods that occur from storms of high intensity having a duration of 1 day or less
Small-area flood
storage confinement for other water use
Storage reservoir (dam)
structure or provision to reduce the peak discharge of flood by temporarily delaying the flow and reducing the velocity
Detention reservoir
includes all measures that will reduce flood flows in watershed of small rivers and their tributaries
headwater flood control
measures that reduces the impacts of flood in the outlets and lower reaches of the watershed, including floodplains
downstream flood control
include those that affect the channel itself and those reduce sediment from upper tributaries; as well as maintenance in the channel to prevent the collection of debris and to reduce sediment from eroding banks
Preventive maintenance
The process of determining the stage height, storage volume, and outflow rate from a reservoir or a stream reach for a particular inflow hydrograph
Flood routing
includes those measures that increase the channel capacity like increasing cross section (deepening or widening the channel), increasing velocity (deepening the channel or lowering the water level at the outlet, and straightening)
Channel improvement
accomplished by spreading the inflow over a considerable area. This method is applicable only in special situations, particularly in arid regions
underground storage
Natural or artificial channel that shortens a meandering stream. its purpose is to increase the velocity, to shorten the channel length and to decrease the length of leeves
Cutoff
embankments along streams or on flood plains designed to confine the river flow to a definite width for the protection of surrounding land from overflow. These may be designed either to confine the river flow for a considerable distance or to provide local protection
levees
