CPESC Questions and Answers 100% Solved
Wind erosion The process in which by the actions of wind a soil particle is detached and
removed from its location
Types of wind erosion: Surface creep soil particles begin to roll along the surface
Saltation Soil particles begin to be lifted into the air but fall quickly back to the surface,
bouncing and possibly dislodging other particles
Suspension Soil particles are lifted into the air and are blown by wind to a location far
from their origin
Factors that affect soil loss from wind erosion Compaction, Moisture, cover, wind speed
Managing wind erosion forming a less erodible surface by increasing soil moisture,
chemical binders, vegetation
Reduce surface wind speed. surface cover orientation of surface, wind screen
,wind erosion equation E = 1.7(s/1.5)(365-p)(f/15)235
E=total spendable particulates, lb/day/acre
s=silt content, percent
p=# days per year with > 0.01" rainfall
f=percent time with wind speed> 12 mph at mean pile height
Hydrology Study of the movement, distribution and quality of surface water
Planning considerations for runoff management Must evaluate: Pre-developed conditions,
during construction, developed conditions
Factors affecting runoff precipitation, watershed area, soil permeability, ground cover,
antecedent moisture, storage in watershed, time parameters
managing water Runoff, run-on, flow thru, dewatering, diversion practices, slowing
practices, inflitration practices, armoring, pumping
,Predicting runoff TR-55, rational method, velocity, volume, peak rate of discharge
Hydrograph Expression of the surface runoff volume fowling to a given point with
respect to important time factors
Important Time Factors Time of concentration Time it takes runoff to travel from the
hydraulically most distant point in the watershed to the design point or point of discharge
Important Time Factors Travel Time Time it takes runoff to travel from one point to
another point down slope along a hydraulic segment in a watershed
Managing water - Runoff management practices Managing communication, managing
work, managing water, managing erosion, managing sediment
Increasing the velocity of water by 2x increases erosive energy by 4x
increases the size of particle carried by 64x
increases the mass of soil being carried by 32x
, Managing water - Open Runoff Conveyance Vegetation without root reinforcement,
vegetation with root reinforcement, Articulated concrete, aggregate, concrete slope paving, other
manufactured linings
Managing water - Closed Runoff Conveyance Vegetation without root reinforcement,
concrete slope paving, level spreaders
Managing water - Outlet Stabilization Vegetation with root reinforcement, articulated
concrete, aggregate
Culvert Outlets points of high energy and velocity; they must have scour protection or the
soils will erode
Short culverts need energy dissipaters to reduce erosion
Headwalls must be stabilized and protected from erosion
Disturbance happens Development and progress cannot happen without some soil
disturbance
Wind erosion The process in which by the actions of wind a soil particle is detached and
removed from its location
Types of wind erosion: Surface creep soil particles begin to roll along the surface
Saltation Soil particles begin to be lifted into the air but fall quickly back to the surface,
bouncing and possibly dislodging other particles
Suspension Soil particles are lifted into the air and are blown by wind to a location far
from their origin
Factors that affect soil loss from wind erosion Compaction, Moisture, cover, wind speed
Managing wind erosion forming a less erodible surface by increasing soil moisture,
chemical binders, vegetation
Reduce surface wind speed. surface cover orientation of surface, wind screen
,wind erosion equation E = 1.7(s/1.5)(365-p)(f/15)235
E=total spendable particulates, lb/day/acre
s=silt content, percent
p=# days per year with > 0.01" rainfall
f=percent time with wind speed> 12 mph at mean pile height
Hydrology Study of the movement, distribution and quality of surface water
Planning considerations for runoff management Must evaluate: Pre-developed conditions,
during construction, developed conditions
Factors affecting runoff precipitation, watershed area, soil permeability, ground cover,
antecedent moisture, storage in watershed, time parameters
managing water Runoff, run-on, flow thru, dewatering, diversion practices, slowing
practices, inflitration practices, armoring, pumping
,Predicting runoff TR-55, rational method, velocity, volume, peak rate of discharge
Hydrograph Expression of the surface runoff volume fowling to a given point with
respect to important time factors
Important Time Factors Time of concentration Time it takes runoff to travel from the
hydraulically most distant point in the watershed to the design point or point of discharge
Important Time Factors Travel Time Time it takes runoff to travel from one point to
another point down slope along a hydraulic segment in a watershed
Managing water - Runoff management practices Managing communication, managing
work, managing water, managing erosion, managing sediment
Increasing the velocity of water by 2x increases erosive energy by 4x
increases the size of particle carried by 64x
increases the mass of soil being carried by 32x
, Managing water - Open Runoff Conveyance Vegetation without root reinforcement,
vegetation with root reinforcement, Articulated concrete, aggregate, concrete slope paving, other
manufactured linings
Managing water - Closed Runoff Conveyance Vegetation without root reinforcement,
concrete slope paving, level spreaders
Managing water - Outlet Stabilization Vegetation with root reinforcement, articulated
concrete, aggregate
Culvert Outlets points of high energy and velocity; they must have scour protection or the
soils will erode
Short culverts need energy dissipaters to reduce erosion
Headwalls must be stabilized and protected from erosion
Disturbance happens Development and progress cannot happen without some soil
disturbance
