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CHAPTER 2 PRECIPITATION


PRECIPITATION


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TYPE OF PRECIPITATION


TYPE OF PRECIPITATION


TYPE OF PRECIPITATION


CLASSES OF PRECIPITATION


CLASSES OF PRECIPITATION


CLASSES OF PRECIPITATION


FORMATION OF PRECIPITATION


FORMATION OF PRECIPITATION


ANNUAL PRECIPITATION


ACID PRECIPITATION


CONTAMINATION OF PRECIPITATION


TERMS OR MEASUREMENTS


EXAMPLE 2.1


SOLUTION 2.1 1.08 = 0.18/(10/60)hr 1.26 = 0.21/(10/60)hr


TYPE OF RAIN GAUGES


TYPE OF RAIN GAUGES Rain Gauges

Record

Weighing Tipping bucket Float

Non- Record


TYPE OF RAIN GAUGES Rain gauge


TYPE OF RAIN GAUGES Non Record


TYPE OF RAIN GAUGES Weighing gauge


TYPE OF RAIN GAUGES Tapping Bucket


TYPE OF RAIN GAUGES Float Type


POINT PRECIPITATION DEW POINT Dew point is measured by the OUTDOOR HUMIDITY/TEMP SENSOR. The dew point temperature is derived from the outdoor temperature and relative humidity measurements. OUTDOOR HUMIDITY / TEMP SENSOR


POINT PRECIPITATION WIND CHILL

Wind chill temperature is measured by the WIND SENSOR and OUTDOOR TEMPERATURE SENSOR. It is calculated from wind speed and outdoor temperature measurements by the ULTIMETER weather station.


LOCATION


POINT and LOCATION Ideal Placement of your Gauge In open areas strive to be twice as far from obstacles as they are high. In developed areas strive to be as far from obstacles as they are high. In open areas place the gauge top approx. 2 feet off the ground. Make sure your gauge is level Distance from obstacles

In developed areas place the gauge top approx. 5 feet off the ground


MISSING DATA Arithmetic Mean Method

Quadrant Method

Normal Ratio Method

Gage Consistency


Arithmetic Mean Method

EXAMPLE


Arithmetic Mean Method

EXAMPLE 2.2

694-69.4 = 624.6 694 + 69.4 = 763.4


EXAMPLE

Normal Ratio Method


Normal Ratio Method

EXAMPLE 2.3


EXAMPLE

Quadrant Method


Quadrant Method EXAMPLE 2.4


If all station coordinated in quadrant, calculate all station

EXAMPLE 2.4

Draw coordinates in the quadrant Calculate L2

II

I B

Select one nearest point to A every quadrant ( only one point – lower L2 )

F A D E

Calculate Wi and WiPi (Table) III Px = Total (WiPi) (Table)

G

C

IV


Quadrant Method correction

EXAMPLE 2.4

25.5

42.5

42.66 42.66 mm


EXAMPLE

Gage Consistency


EXAMPLE

Gage Consistency

Pa = Px [Ma/Mo]

correction

Px


EXAMPLE

Gage Consistency


Gage Consistency

EXAMPLE 2.5


Gage Consistency

EXAMPLE 2.52.5- cont

Calculate point for 1927, 1928, 1929

correction


Gage Consistency

EXAMPLE 2.52.5- cont


MEAN AREA PRECIPITATION Arithmetic Mean Method Thiessen Polygon Method

Isohyetal Method


Arithmetic Mean Method

MEAN AREA PRECIPITATION


Thiessen Polygon Method

MEAN AREA PRECIPITATION


Thiessen Polygon Method

MEAN AREA PRECIPITATION


Thiessen Polygon Method

MEAN AREA PRECIPITATION


Thiessen Polygon Method

MEAN AREA PRECIPITATION Draw boundary and stations in the graph paper (black dotted line) Connect every station by draw the straight line ( blue dotted lines) Construct 90o –perpendicular bisectors (red solid lines) Connect each line to forming polygons

Area of polygons in boundary


Thiessen Polygon Method

EXAMPLE 2.6


Isohyetal Method EXAMPLE 2.6


Isohyetal Method

Draw the boundary in the graph paper Draw stations precipitation Start point from the lower precipitation Estimate extra point by draw the line by connect to each point precipitation Draw contour lines by scale unit from boundary to boundary Find the area and calculate (table)


Isohyetal Method

EXAMPLE 2.7


Isohyetal Method

EXAMPLE 2.7


THE END


Hydrology class [C2]