RAINFALL - RUNOFF Flashcards
a graph that shows how the flow of water in a river changes over time
HYDROGRAPH
a graphical representation that shows how rivers or streams flow over
time, particularly in response to rainfall
HYDROGRAPH
It is the normal flow of the water at the river
BASE FLOW
the normal or steady contribution of groundwater to the stream. This flow
decreases gradually over time as groundwater levels drop.
BASE FLOW
an increase in river flow due to surface runoff
RISING LIMB
the highest point on the hydrograph, indicating the maximum river
flow during the storm event
when the rate of discharge is greatest
PEAK DISCHARGE
represents the time between the center of the peak precipitation and the
peak discharge. It measures the time it takes for the peak to occur.
LAG TIME
indicates a rapid response of watershed, which means that the peak discharge occurs faster after the rain begins
SHORTER LAG TIME
delays the peak to reach, since they allow
more water to infiltrate the soil or be absorbed by vegetation before reaching the river
LONGER LAG TIME
represents the gradual reduction in river flow as the runoff from the
storm diminishes
FALLING LIMB
when discharge decreases and the ricer level falls
FALLING LIMB
a certain point in which the slope of the hydrograph changes, which indicates that the inflow from the storm has already stopped
and the stored water in the river gradually diminishes
INFLECTION POINT
shows how groundwater levels
gradually decrease back to normal after the storm
RECESSION CURVE
Hydrographs help forecast floods by analyzing
past rainfall and river response. This allows for timely warnings and effective
flood management strategies.
FLOOD PREDICTION MANAGEMENT
Assist in managing water resources by
providing insights into streamflow patterns and water availability. This information
helps in making informed decisions about water allocation for various uses.
WATER RESOURCE MANAGEMENT
Hydrographs are essential for engineering projects
like dams, culverts, and drainage system design. Engineers use them to
determine inflow to reservoirs and to design systems that manage stormwater
effectively, reducing flood risks.
ENGINEERING APPLICATIONS
refers to the process of
dividing a stream flow
hydrograph into its
different components, such
as base flow (water from
groundwater) and direct
runoff (water from
precipitation or snowmelt).
HYDROGRAPH SEPARATION
This method of base flow separation
is the simplest of all three methods.
Separating baseflow using the
_______________ is suitable only
for individual storm events. For
continuous hydrographs, other techniques must be used.
STRAIGHT LINE METHOD
is a simple and common
approach to separating base flow
from direct runoff in a hydrograph.
It assumes that base flow declines at a constant rate during and after
a storm event, and uses a fixed
time interval after the peak flow to
distinguish between base flow and
direct runoff.
FIXED BASED METHOD
(FIXED INTERVAL METHOD)
a
technique used to separate base dlow from direct runoff in a
stream flow hydrograph. The method assumes that
the decline in flow over time is primarily due to base flow, as direct
runoff diminishes quickly after the
peak
RECESSION CURVE METHOD
type of hydrographic method that requires hydrologist to
perform the method,
usually labor intensive
and results are
subjected to individual
hydrologist
interpretation
MANUAL METHOD
A type of hydrographicethod which utilizes computers in
order to eliminate result
subjectivity and reduce
time required for
stream flow record
analysis.
AUTOMATED METHOD
Applications of hydrograph separation
1.Estimation of
groundwater
discharge/
recharge
2. Estimation
of flooding
potential
3. Calibration of model
4. Assessment
of water
development
impacts
represents the direct runoff resulting from 1 cm of effective rainfall
over a drainage area.
UNIT HYDROGRAPH
