Terms Flashcards
wearing away by friction
abrasion
the course along which the center line of a roadway or channel is located
alignment
the angle of which the slope face of a bank of loose material makes with horizontal
angle of repose
rainfall that has recently preceded the storm event being analyzed
antecedent precipitation
a structure for collecting runoff from relatively small paved areas
area drain
a vertical wall at the end of a culvert to support the pipe and prevent her from spilling into the channel
headwall
cross-sectional area flow of a pipe or channel divided by the wetted perimeter
hydraulic radius
the load-supporting capacity of soil
bearing capacity
planing or smoothing the ground surface
blading
a source of earth fill materials used in construction of embankments or other earth fill structures
borrow area
receptacle with a sediment bowl or sump for diverting surface water to a subsurface pipe
catch basin
a graph showing, for a given point on a channel, the discharge, stage, velocity or other property of water with respect to time
hydrograph
vegetative cover, residue, and surface roughness of the soil as they may affect potential runoff
hydrologic condition
the process determining the location of elevations from the plotted locations of known elevations
interpolation
a formula expressing the principle of conservation of mass as applied to flow of water, which states that the product of cross section of flow and velocity at any point in a channel is a constant
continuity equation
an imaginary line, or its representation on a map, following all points at the same elevation above or below and given datum
contour line
the depth of flow in an open channel at which critical flow occurs. For given flow rate, depths greater than critical results in subcritical, or tranquil, flow. Those smaller than critical result in supercritical, or rapid, flow.
critical depth
an unstable flow condition in open channel which occurs at critical depth
critical flow
velocity of flow in an open channel which occurs at critical depth
critical velocity
the lowest point of an internal cross section of a pipe or channel
invert
any structure not classified as a bridge which provides a waterway or other opening under a road
culvert
a small ditch, constructed in flat bottoms of larger ditches or detention basins, to facilitate their drainage during periods of low flow
low-flow channel
horizontal reference plane used as a basis for computing elevations
datum
and impoundment, normally dry, for temporarily storing storm runoff from a drainage area to reduce the peak rate of flow
detention basin
flow rate in a culvert, pipe, or channel
discharge (q)
a channel, with or without a supporting ridge on the lower side, constructed across a slope to intercept surface runoff
diversion
the area drained by channel or subsurface drain
drainage area
the study of soil from the standpoint of higher plants and crop production
edaphology
the altitude relative to a given datum or a scale drawing of the facade of a structure.
elevation
an arrangement for conveying surface water to and under drain
inlet
a channel for safety conveying flood discharges exceeding the capacity of the principal spillway of a detention or retention pond
emergency spillway
the susceptibility of soil material to detachment and transportation by running water or wind
erodibility
detachment and movement of soil or rock fragments by water, wind, ice and gravity
erosion
losses before runoff begins, including infiltration, evaporation, interception by vegetation, and water retention in surface depressions
initial abstraction
a formula for calculating the velocity of flow in a channel as a function of relative roughness, cross-sectional configuration, and gradient
Manning’s equation
a vegetative buffer zone for removing sediments and pollutants before runoff reaches ponds, waterways, and other drainage facilities
filter strip
preparation of the subgrade preceding placement of surfacing materials
fine grade
an open surface storage area with no outlet, except an emergency spillway, which permits runoff to infiltrate the soil
infiltration basin
soil water that moves by gravity, in contrast to capillary and hydroscopic water
free water
the downward entry of water into the surface of a soil or other material, as contrasted with percolation, which is movement of water through soil layers or material
infiltration
property of a material through which water will not flow under ordinary hydrostatic pressure
imperviousness
the completed surfaces of lawns, walks and roads brought to grades as designed
finished grade
the undisturbed natural surface of the ground
natural grade
the grades established in preparation for top surfacing
subgrade
degree of inclination of a surface, road, or pipe, usually expressed as a percentage
gradient
the concept of a closed system, involving the transformation of water from the vapor phase to the liquid (and solid) phase back to the vapor phase, and the movement of that water
hydrologic cycle
a natural or constructed channel, usually broad and shallow and covered with erosion resistant vegetation, used to conduct surface runoff
grassed waterway
the greatest a proportion of precipitation that could possibly be retained by a specific soil and land use combination
maximum potential retention (s)
an extension of the rational method for calculating the rate of runoff from a drainage area, including provisions for antecedent precipitation and for development of hydrographs
modified rational method (MRM)
percentage, by weight, of water contained in the soil or other material, usually based on dry weight
moisture content
point of water disposal from a stream, River, Lake, Tidewater, or artificial drain
outlet
maximum instantaneous flow rate resulting from a given storm condition at a specific location
peak discharge
movement of water toward water table
percolation
measure of alkalinity or acidity. pH 7 in neutral pH 6.5 represents a desirable degree of soil acidity
pH
a component of retention or detention ponds, generally constructed of permanent materials. It is desired to regulate the normal water level, provide flood protection, and or reduce the frequency of operation of the emergency spillway
principal spillway
the study of the soil as a natural body, including its origin, characteristics, classification, and description
pedology
the rate at which rain falls. measured in inches per hour
rainfall intensity (i)
the formula for calculating the peak runoff rate from a drainage area based on land use, soils, land slope, rainfall intensity, and drainage area
rational method
the portion of a hydrograph that occurs after peak when the flow rate decreases
recession (hydrograph)
a reservoir, containing a permanent pool, for temporarily storing storm runoff and reducing the storm runoff rate from a drainage area
retention basin
the portion of a hydrograph preceding the peak when the flow rate increases
Rising limb (hydrograph)
a factor in the Manning formula representing the effect of channel or conduit roughness on energy losses in the flowing water
roughness coefficient (n)
the part of precipitation carried off from the area on which it falls. Also, the rate of surface discharge of the above. the ratio of runoff to precipitation is a coefficient, expressed as a decimal
runoff
National Resource Conservation Service…formely Soil Conservation Service, a federal agency in the Department of Agriculture, dealing with erosion and flood control
NRCS/ SCS
solid material, both mineral and organic, in suspension, being transported, or having being moved from its original site, by air, water, gravity, or ice
sediment
a reservoir formed by the construction of a barrier or dam built at a suitable location to permit the settling out of sediment, before releasing water
sediment basin
Force per unit area exerted on a wetted area of a channel, acting in the direction of flow
shear stress
a soil classification system based on infiltration and potential runoff characteristics
hydrologic soil group (HSG)
distance between approaching vehicles when first visible to one another on a horizontal or vertical curve
sight distance
the face of an embankment or a cut section. any ground whose surface makes an angle with the horizontal plane
slope
a pervious backfield trench containing a pipe with perforation or open joints for the purpose of intercepting groundwater or seepage
subdrain
the rise of the outer edge of the pavement relative to the inner edge at a curve in a highway, expressed in feet per foot, intended to overcome the tendency of speeding vehicles to overturn when rounding a curve
superelevation
constructed or natural grass or vegetated waterway
swale
a straight road segment connecting two curves
tangent
the time for water to flow from the hydraulically most remote point in a drainage area to the point of interest
time of concentration (Tc)
period of time from the peak of a hydrograph until it reaches the beginning flow rate
time of recession (Trec)
period of time from the beginning flow rate until the peak flow rate is reached
time of rise (Trise)
the time for runoff to flow from one point in a drainage area to another
travel time (Tt)
a reservoir that has a provision for removing pollutants from stormwater runoff by retaining the runoff from high frequency storms (1-2 yr freq.) prolonged periods 18 to 36 hours
water quality basin
region or area contributing to the supply of a stream or lake
watershed
the level below which the ground is saturated
water table
an opening in the crest of a dam or an embankment to discharge excess water, also used for measuring the rate of discharge
Weir
the length of a wetted contact between the water and the containing conduit, measured along a plane that is perpendicular to the conduit
wetted perimeter
a line between two points on the ground and indicated on a survey map, reference to North, which is the basis for property boundaries or other information on a survey showing horizontal relationships of objects to each other
basis of bearing
a fixed point on the ground who’s location and relative elevation is known, marked by temporary or permanent markers, usually shown on topographic survey
benchmark
a branch of engineering science concerned with the flow of liquids, usually in channels, pipes, or porous media
hydraulics
the study of water
hydrology
graphical device used to solve mathematical or scientific equations with multiple variables. mathematical equation that has been transferred into graphical representation
nomograph
a line of elevations which are higher than elevations on the other side. often defines the boundries of a watershed. (water spreading)
Ridge
align of elevations which are lower than elevations on either side. often define stream channels or flowlines for watershed. (water gathering)
Valley
the magnitude of a force exerted along the long axis of an object which will try to tear apart
Tension
the result of subjecting a material to stress, resulting in a reduction of volume, measures concrete strength
Compression
a substance’s to be deformed temporarily, when force is applied
Elasticity
describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces
Plasticity
the internal resistance a material offers to being deformed
Stress
a failure of a material by its being pulled apart by tension
Rupture
the stress state caused by a pair of opposing forces acting along parallel lines of action through the material
Shear
the progressive and localized damage that occurs when a material is subject to cyclical loading
Fatigue
weight of a structure per unit area
Dead Load
the dynamic load applied to a structure
Live Load
vegetation that poisons soil to limit competition
Allelopathy
Soil pH is a measure of the acidity and alkalinity in soils. pH levels range from 0 to 14, with 7 being neutral, Under 7, acidic and above 7, alkaline.
What is the optimum pH range for most plants?
5.5 to 7.0
relatively large amounts, the soil supplies nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur
Macronutrient
There are 7 essential plant nutrient elements, boron (B), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), molybdenum (Mo), chlorine (Cl). They constitute in total less than 1% of the dry weight of most plants
Micronutrient
abnormal reduction or loss of the normal green coloration of leaves of plants, typically caused by iron deficiency in lime-rich soils, or by disease or lack of light
Chlorosis
the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere
Transpiration
cube shape tree
Pleaching
the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms
Humus
a broad-based approach that integrates practices for economic control of pests
Integrated Pest Management - IPM
how many square feet in an acre?
43,560 (acre foot = 12” depth)
