hydrology 2 Flashcards
Is the water beneath the ground surface contained in void spaces.
GROUNDWATER
is an underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well
AQUIFER
is the level at which the groundwater pressure is equal to atmospheric pressure.
WATER TABLE
Is a zone within the Earth that restricts the flow of Groundwater from one aquifer to another.
AQUITARD
comprise layers of either clay or non-porous rock with low hydraulic conductivity.
AQUITARD
an aquifer with the water table as its upper boundary
UNCONFINED AQUIFER
aquifer found between two relatively impermeable layers
CONFINED AQUIFER
it is a confined aquifer containing groundwater that will flow upward through a well without a need for pumping.
Artesian Aquifer/ well
is an excavation or structure created in the ground by digging, driving, boring or drilling to access groundwater in the underground aquifers.
WATER WELL
it is a narrow shaft drilled in the ground as part of groundwater site assessment.
BOREHOLE
The imaginary surface that everywhere coincides with the piezometric head of the water in the aquifer.
PIEZOMETRIC SURFACE
Is the portion of the stream flow that comes from groundwater
BASEFLOW
natural or intentional infiltration of surface water into the ground system.
GROUNDWATER RECHARGE
is groundwater that has remained in an aquifer for thousands or even millions of years.
FOSSIL WATER
Surface waters on rivers
RIVER RUNOFF
occurs during high intensity rainfall events
Infiltration excess runoff
When rainfall intensity is less than soil infiltration rate, prolonged rainfall will saturate the soil and no more water could be held.
SATURATION EXCESS RUNOFF
Point of rise, Rising Point of Inflection, Peak
Rising limb
Rising Point of Inflection, Peak, Recession point of Inflection
Crest segment
Peak, recession point of inflection, End point of recession
Recession limb
It is the ascending curved portion of
the hydrograph.
Rising limb
It shows the increase in discharge
from the catchment area in response
to the rainfall.
Rising limb
Peak segment is shown by inverted U in
the hydrograph.
Crest Segment
Highest concentration of runoff
Crest segment
It is the highest point on the graph
where the discharge is maximum.
crest segment
The falling limb is the extension of
the graph from the peak flow rate.
recession limb
represents the withdrawal of water
from the storage built up during the
early phase of hydrograph.
recession limb
types of hydrograph
unit hydrograph
* storm hydrograph
* snyder’s synthetic hydrograph
* annual hydrograph
* monthly hydrograph
* seasonal hydrograph
* flood hydrograph
a direct runoff hydrograph that is a result of one unit (one
inch or one cm) of constant intensity uniform rainfall occurring
over the entire watershed.
unit hydrograph
a way of displaying how the
discharge of a river can
change over time in response
to a rainfall event
storm hydrograph
it is derived from model and
experience, and it is used to
simulate basin diffusion by
assessing the basin lag based
on a specific method.
snyder’s synthetic hydrograph
This enables the use of
available data to determine a
watershed’s response to
rainfall throughout the year,
and thereby compute a year-
round EIA
annual hydrograph
It represents the variation of
rainfall over a month.
Monthly hydrograph
It shows the variation of
discharge in a season.
seasonal hydrograph
are graphs
that show how a drainage
basin responds to a period of
rainfall.
flood hydrograph
There are four ways that rainfall contributes to river
runoff:
Overland surface runoff
* interflow (subsurface runoff)
* baseflow from groundwater
* rainfall onto river channel
is the flow of water occurring
on the ground surface when excess rainwater, stormwater,
meltwater, or other sources, can no longer sufficiently
rapidly infiltrate in the soil.
Overland surface runoff
is relatively rapid
flow toward the stream channel that occurs below the
surface. It occurs more rapidly than baseflow, but
typically more slowly than surface runoff.
interflow
is the portion of the
streamflow that is sustained between precipitation
events, fed to streams by delayed pathways. It should
not be confused with groundwater flow.
baseflow from groundwater
Channel precipitation can be
defined as rainfall and throughfall intercepted by
the flowing stream channel and waterbodies, that
without contribution to infiltration, subsurface flow,
and ground water, incorporated into stream flow
rainfall into channel
Overland surface runoff and interflow travel
much faster than groundwater, hence they are combined into a
term
Direct runoff
-A SURFACE water flow that occurs as a result of rainfall.
Flow event
-the inflows to any water system or area is equal to its outflows plus
change in storage during a time interval.
water balance calculation
-A portion of the precipitation seeps into the ground to replenish
Earth’s groundwater.
rainfall runoff
-drawn to represent the characteristic time graph of decreasing
total runoff
recession curve
-the volume of fluid which passes per unit time
total flow volume
-Water that flows over the ground surface directly into streams,
rivers, or lakes
direct runoff
portion of streamflow that is not directly generated from the
excess rainfall during a storm event.
baseflow
is the part of the total
rainfall that contributes to direct runoff.
effective rainfall
