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