Team Taligsik Hydrology Report
Team Taligsik Hydrology Report
Team Taligsik Hydrology Report
PRECIPITATION
GROUP MEMBERS
NIÑO LOUIENO M. GIVA
JARIIR M. ALIM JHON DAVE A.YOCA
DJEE B. TOLENTINO
JERAME F. BAAL
ANDONY CALINOG
ELLARANE G. BUSTILLO
Formation of Precipitation
Precipitation
occurs when water vapor
condenses into droplets or ice crystals and
becomes heavy enough to fall under gravity.
TYPES OF PRECIPITATION
1.CONVECTIVE PRECIPITATION
- The air above the land area gets
heated up due to some cause. Most of
this warmer air rises up, cools, and
precipitates. Convective precipitation is
showery by nature. This type of
precipitation occurs in varying intensities.
2. CYCLONIC PRECIPITATION
* Non-Frontal Precipitation
- This is a cold moist air mass boundary that moves and
results in precipitation.
3. OROGRAPHIC PRECIPITATION
INTENSITY(i):
AMOUNT OF RAIN IN A CERTAIN TIME (mm/hr.)
INTENSITY IS HOW MUCH RAIN FALLS AT ANY GIVEN
MOMENT.
DURATION(d):
TIME AT WHICH RAIN OCCURS (hr.)
THE AMOUNT OF TIME FROM THE START TO THE END OF
A RAINFALL EVENT.
DEPTH(t):
VOLUME OF RAIN OVER AN AREA (d= Vol./A)
FREQUENCY
THE FREQUENCY OF RAINFALL OCCURRED.
REPEATFOR THE RAIN AND HOW OFTEN WE WILL
EXPECT TO SEE RAIN THAT IS AT LEAST THIS INTENSE.
DIFFERENT
TYPES OF
RAIN GAUGES
What Is Rain Gauge?
1.Arithmetic Mean
Method - if the normal
precipitation at various
stations are within 10%
of the normal
precipitation at station
"x".
2. Normal Ratio Method -
if the normal
precipitations vary more
than 10%, then Px is
estimated by weighing
the precipitation at
various stations by the
ratios of normal annual
precipitation
EXAMPLE
The normal annual rainfall at stations A,
B, C, and D are 60,75,80,&100 cm,
respectively. In 1994, station C was not
working & stations A, B, & D were
recorded annual precipitation of 90,60,&
70 cm, respectively. Estimate the annual
rainfall at station C.
SOLUTION
EXAMPLE
Isohyetal Method
• The stations and rainfall values are plotted on a map to a suitable scale.
• The contours of equal precipitation (isohyets) are drawn. The accuracy
depends on the construction of the isohyets and their intervals.
• The area between successive isohyets is computed and multiplied by the
numerical average of the two contour (isohyets) values.
• The sum of item 3 divided by the drainage area provides the weighted
average precipitation.
Isohyetal Method
The average precipitation is
then computed using the
formula:
Example:
The isohyets due to a storm in a
catchment together with the area
of the catchment bounded by the
isohyets are given below.
Estimate the mean precipitation
due to the storm using Isohyetal
Method.
Solution:
DOUBLE MASS ANALYSIS