chapter 4 Flashcards
Overland flow definition
the flow of water that occurs when excess storm-water, melt-water, or other sources flows over the earth’s surface.
overland flow might occur becauses
- either soil is saturated to full capacity,
- rain arrives more quickly than soil can absorb it,
- or impervious areas (roofs, pavement and cities concrete) send their runoff to surrounding soil that cannot absorb all of it.
overland flow cause
soil erosion by water.
overland flow is also called ………………………… and it means…………………..
a nonpoint source
runoff that occurs on the ground surface before reaching a channel
nonpoint source pollution means
If a nonpoint source contains man-made contaminants, or natural forms of pollution (such as rotting leaves) the runoff
drainage basin means
A land area which produces runoff that drains to a common point
surface runoff in urban areas cause
of urban flooding which can result in property damage, damp and mold in basements, and street flooding.
how is surface runoff generated?
- either by rainfall
- snowfall
- by the melting of snow, or glaciers.
Typically snowmelt will peak in the
spring
glacier melt in the
summer
Typically snowmelt will peak in the spring and glacier melt in the summer, leading to
pronounced flow maxima in rivers affected by them.
The determining factor of the rate of melting of snow or glaciers is
- air temperature
- the duration of sunlight.
high mountain regions, ……………………..frequently ……………on sunny days and …………………………….. for this reason.
streams
rise
fall on cloudy ones
In areas where there is no snow, runoff will come from
rainfall
Infiltration excess overland flow occur when
the rate of rainfall on a surface exceeds the rate at which water can infiltrate the ground, and any depression storage has already been filled.
flooding excess overland flow more commonly occurs in
arid and semi-arid regions
Infiltration excess overland flow where……………………………………….. and ………………………………………………..because of…………………………………………., or in …………………………areas.
rainfall intensities are high
the soil infiltration capacity is reduced
surface sealing
paved
where rainfall intensities are high and the soil infiltration capacity is reduced because of surface sealing, or in paved areas. This occurs largely in
city areas where pavements prevent water from flooding.
saturation excess overland occur when
When the soil is saturated and the depression storage filled, and rain continues to fall, the rainfall will immediately produce surface runoff.
saturation excess overland flow is also called
saturated overland flow
Antecedent soil moisture
Soil retains a degree of moisture after a rainfall
Antecedent soil moisture affect
residual water moisture affects the soil’s infiltration capacity.
During the next rainfall event, the infiltration capacity will cause
the soil to be saturated at a different rate
The higher the level of antecedent soil moisture, the………………….
the more quickly the soil becomes saturated
The higher the level of antecedent soil moisture, the more quickly the soil becomes saturated. Once the soil is saturated ……………………………….. occurs
runoff
subsurface return flow
After water infiltrates the soil on an up-slope portion of a hill, the water may flow laterally through the soil, and exfiltrate (flow out of the soil) closer to a channel.
subsurface return flow is also called
through flow
hydraulics is a derivative of the Greek words
hydro (meaning water) and aulis (meaning tube or pipe)
Originally, the science of hydraulics covered the
physical behavior of water at rest and in motion
the term hydraulics has broadened its meaning to include the ………………………..
physical behavior of all liquids
the physical behavior of all liquids includes
power hydraulics
power hydraulics
confined liquids are used under controlled pressure to do work
Although the modern development of hydraulics is comparatively recent, the ancient cultures were familiar with many hydraulic principles and applications. They ………………………………………
conveyed water along channels for irrigation and domestic purposes, using dams and sluice gates to control the flow