secondary validation - rainfall data
DESCRIPTION
SECONDARY VALIDATION - RAINFALL DATA. PRIMARY VALIDATION ALREADY DONE ON INDIVIDUAL STATION BASIS SECONDARY VALIDATION IDENTIFY SUSPECT VALUES BY HAVING COMPARISON WITH NEIGHBOURING STATIONS DIVISIONAL DPCs TO CONTINUE AT SDPCs RAINFALL NOT HIGHLY CORRELATED IN SPACE & TIME !! - PowerPoint PPT PresentationTRANSCRIPT
HYDROLOGY PROJECTTechnical Assistance
SECONDARY VALIDATION - RAINFALL DATA
• PRIMARY VALIDATION ALREADY DONE* ON INDIVIDUAL STATION BASIS
• SECONDARY VALIDATION* IDENTIFY SUSPECT VALUES BY HAVING COMPARISON
WITH NEIGHBOURING STATIONS
• DIVISIONAL DPCs* TO CONTINUE AT SDPCs
• RAINFALL NOT HIGHLY CORRELATED IN SPACE & TIME !!
* NOT A ONE-TO-ONE - COMPARISON DIFFICULT
* BETTER CORRELATION - LARGER TIME INTERVALS
* MISTAKES & SUSTAINED SYSTEMATIC ERRORS
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HYDROLOGY PROJECTTechnical Assistance
SPATIAL CORRELATION
• MAJOR INFLUENCING FACTORS– LEVEL OF AGGREGATION IN TIME
– DISTANCE
– TYPE OF PRECIPITATION
– PHYSIOGRAPHIC FACTORS
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HYDROLOGY PROJECTTechnical Assistance
KHEDA CATCHMENT - SABARMATI
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HYDROLOGY PROJECTTechnical Assistance
Spatial Correlation - Daily Rainfall (Kheda Catchment)
Distance (km)120110100908070605040302010
Cor
rela
tion
1.0
0.8
0.6
0.4
0.2
0.0
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HYDROLOGY PROJECTTechnical Assistance
Spatial Correlation - 10 Daily Rainfall (Kheda Catchment)
Distance (km)12011511010510095908580757065605550454035302520151050
Cor
rela
tion
1.0
0.8
0.6
0.4
0.2
0.0
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HYDROLOGY PROJECTTechnical Assistance
Spatial Correlation - Monthly Rainfall (Kheda Catchment)
Distance (km)12011511010510095908580757065605550454035302520151050
Cor
rela
tion
1.0
0.8
0.6
0.4
0.2
0.0
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HYDROLOGY PROJECTTechnical Assistance
Spatial Correlation - Monthly Rainfall (Region A)
Distance (km)252423222120191817161514131211109876543210
Cor
rela
tion
1.0
0.8
0.6
0.4
0.2
0.0
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HYDROLOGY PROJECTTechnical Assistance
REGION A
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HYDROLOGY PROJECTTechnical Assistance
Spatial Correlation - Extended Region
Distance (km)80757065605550454035302520151050
Cor
rela
tion
1.0
0.8
0.6
0.4
0.2
0.0
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HYDROLOGY PROJECTTechnical Assistance
EXTENDED REGION
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HYDROLOGY PROJECTTechnical Assistance
USE OF SPATIAL CORRELATION
• PREVAILING SPATIAL CORRELATION– AS BASIS FOR TESTING SPATIAL CONSISTENCY
– SPATIAL INTERPOLATION
• THERE IS LIKELIHOOD OF– REJECTING GOOD BUT ANAMOLOUS DATA
– ACCEPTING BAD DATA
• RELIANCE ON STATION REPUTATION– TYPE OF STATION
– PAST RECORD ON QUALITY
– OBSERVER SINCERITY & PAST RECORDSOHS - 11
HYDROLOGY PROJECTTechnical Assistance
SECONDARY DATA VALIDATION
• SCREENING OF DATA• MULTIPLE TIME SERIES GRAPHS• DAILY RAINFALL TABULATION FOR
NEIGHBOURING STATIONS• APPLYING DATA LIMITS AT LONGER
DURATIONS• SPATIAL HOMOGENEITY TEST• VERY COMMON ERRORS
– ACCUMULATION OF RAINFALL OR MISSED ENTRY
– MISSED RAINFALL ON LOW RAINFALL DAYS
• DOUBLE MASS ANALYSIS– LONG TERM SYSTEMATIC SHIFTS
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HYDROLOGY PROJECTTechnical Assistance
DATA VALIDATION
• SCREENING OF DATA– SCREENING AGAINST DATA LIMITS
– TABULAR OUTPUT
– BASIC STATISTICS
• OBJECTIVES– REVIEW PRIMARY VALIDATION
– HARD COPY * MEDIUM FOR SCRIBBLING REMARKS/ DATA VALIDATION
NOTES
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HYDROLOGY PROJECTTechnical Assistance
Daily data and statistics of series MEGHARAJ MPS Year = 1997
Day Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May 1 .0 .0 192.5* .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 2 .0 .0 15.0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 3 .0 .0 1.0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 4 .0 .0 .0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 5 .0 .0 .0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0*
6 .0 .0 .0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 7 .0 .0 1.0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 8 .0 .0 32.0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 9 .0 .0 1.0 25.0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 10 .0 .0 .0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0*. . .. . .. . .
26 132.0* 4.0 54.5 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 27 38.0 312.0* 1.0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 28 54.0 32.5 .0 .0 .0 -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* -99.0* 29 .0 4.5 .5 .0 .0 -99.0* -99.0* -99.0********** -99.0* -99.0* -99.0* 30 .0 12.0 .5 .0 .0 -99.0* -99.0* -99.0********** -99.0* -99.0* -99.0* 31********* 22.0 .0 ********* .0 ********* -99.0* -99.0********** -99.0********** -99.0*
Data 30 31 31 30 31 30 31 31 28 31 30 31 Eff. 30 31 31 30 31 0 0 0 0 0 0 0 Miss 0 0 0 0 0 30 31 31 28 31 30 31 Sum 397.0 401.0 474.5 76.0 5.5 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 Mean 13.2 12.9 15.3 2.5 .2 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 Min. .0 .0 .0 .0 .0 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 Max. 138.0 312.0 192.5 27.5 5.5 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0 -99.0
High 130.0 130.0 130.0 130.0 130.0 .0 .0 .0 .0 .0 .0 .0 Numb 2 1 1 0 0 0 0 0 0 0 0 0 Low .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 Numb 0 0 0 0 0 0 0 0 0 0 0 0
Annual values: Data 365 * Sum 1354.0 * Minimum .0 * Too low 0 Effective 153 * Mean 8.8 * Maximum 312.0 * Too high 4 Missing 212
Exceedance of: - Lower bound ( .00) marked with * - Upper bound ( 130.00) marked with * - Rate of rise ( 320.00) marked with + - Rate of fall ( 320.00) marked with -
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HYDROLOGY PROJECTTechnical Assistance
Comparison of Daily Rainfall at Multiple Stations
PH_ANIOR PH_BHEMPODA PH_RELLAWADA PH_MEGHARAJ
Time
15/08/96
14/08/96
13/08/96
12/08/96
11/08/96
10/08/96
09/08/96
08/08/96
07/08/96
06/08/96
05/08/96
04/08/96
03/08/96
02/08/96
01/08/96
31/07/96
30/07/96
29/07/96
28/07/96
27/07/96
26/07/96
25/07/96
24/07/96
23/07/96
22/07/96
Rai
nfa
ll (m
m)
240
220
200
180
160
140
120
100
80
60
40
20
0
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HYDROLOGY PROJECTTechnical Assistance
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HYDROLOGY PROJECTTechnical Assistance
Tabulation of series, Year 1984
==========Data========== Year mth day hr si KAPADWANJ KATHLAL MAHISA SAVLITANK VADOL PH PH PH PH PH 1984 8 1 .0 .0 .0 .0 .0 1984 8 2 .0 .0 .2 .0 .0 1984 8 3 152.4 99.3 157.4 .0 39.3 1984 8 4 104.1 50.2 87.0 150.0 59.2 1984 8 5 7.7 12.0 18.0 76.0 13.1 1984 8 6 1.5 35.0 .0 16.0 .0 1984 8 7 .0 .0 .0 3.0 .0 1984 8 8 1.3 .0 .0 .0 .0 1984 8 9 .0 13.0 .0 .0 .0 1984 8 10 231.2 157.0 179.0 .0 17.3 1984 8 11 43.2 18.3 64.0 201.0 63.2 1984 8 12 .0 .0 .0 26.0 33.3 1984 8 13 .0 .0 .0 .0 13.1 1984 8 14 .0 .0 20.0 .0 .0 1984 8 15 .0 .0 .0 30.0 .0 1984 8 16 2.6 8.3 16.5 .0 16.3 1984 8 17 .0 .0 .0 20.0 20.2 1984 8 18 32.0 50.3 25.6 .0 37.2 1984 8 19 16.5 8.2 15.0 27.0 19.3 1984 8 20 .0 .0 .0 13.0 .0 1984 8 21 .0 .0 .0 .0 .0
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SCRUTINY BY TABULATION
HYDROLOGY PROJECTTechnical Assistance
Plot of Yearly Rainfall with Data Limits
Vadol Lower Warning Level Upp. Warning Level
Time9897969594939291908988878685848382818079787776757473727170
Rai
nfal
l (m
m)
1,400
1,300
1,200
1,100
1,000
900
800
700
600
500
400
300
200
100
0
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HYDROLOGY PROJECTTechnical Assistance
SPATIAL HOMOGENEITY TESTING
• SPATIAL CORRELATION– CONSISTENCY BETWEEN NEIGHBOURING STATIONS
– COMPARISON OF * OBSERVED VALUE
* VALUE ESTIMATED ON THE BASIS OF NEARBY STATIONS
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HYDROLOGY PROJECTTechnical Assistance
TEST & BASE (NEIGHBOUR) STATIONS
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+
+
+ I
III IV
+ Neighbouring stations
Test station
Selected neighbouringstations
II etc.
Quadrant
II
+++
++
++
+
+
++
+
+
HYDROLOGY PROJECTTechnical Assistance
• SPATIAL ESTIMATE - WEIGHTED AVERAGE– WEIGHTS : INVERSE OF DISTANCE POWER
N
ib
iD
biDt
N
i iPtestP
1/1
/)(1)(
– TEST : ABSOLUTE & RELATIVE
Pobs(t) - Pest(t) Xabs
Pobs(t) - Pest(t) Xrel * S Pest (t)
2
1)( ))()(( tPtPS ii
N
itPest
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HYDROLOGY PROJECTTechnical Assistance
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HYDROLOGY PROJECTTechnical Assistance
Spatial homogeneity check Test station SAVLITANK PH
Year mth day hr si P_obs flag P_est Stdv n
1984 6 14 0 1 9.00 + .00 .00 6 1984 6 15 0 1 14.00 + .00 .00 6 1984 6 16 0 1 23.00 + .00 .00 6 1984 7 2 0 1 52.00 + 14.52 9.71 6 1984 7 6 0 1 47.00 + 2.13 4.51 6 1984 7 25 0 1 25.00 + .32 1.21 6 1984 8 3 0 1 .00 - 96.59 65.70 6 1984 8 4 0 1 150.00 + 78.44 38.47 6 1984 8 5 0 1 76.00 + 20.64 36.20 6 1984 8 10 0 1 .00 - 128.36 93.57 6 1984 8 11 0 1 201.00 + 59.25 42.04 6 1984 8 15 0 1 30.00 + .50 1.89 6 1984 8 19 0 1 27.00 + 16.81 4.91 6 1984 8 28 0 1 8.00 + .00 .00 6 1985 6 13 0 1 9.00 + .00 .00 6 1985 6 14 0 1 14.00 + .00 .00 6 1985 6 16 0 1 8.00 + .00 .00 6 1985 7 2 0 1 21.00 + .07 .37 6 1985 7 6 0 1 47.00 + .73 3.73 6 1985 7 19 0 1 60.00 + 16.05 15.49 6 1985 7 21 0 1 29.00 + 10.41 7.93 6 1985 7 23 0 1 12.00 + .15 .75 6 1985 7 25 0 1 25.00 + 3.15 3.78 6 1985 8 1 0 1 10.00 + .48 1.97 6 1985 8 4 0 1 150.00 + 82.57 76.84 6 1985 8 5 0 1 76.00 + 15.06 37.51 6 1985 8 11 0 1 201.00 + 11.39 53.59 6 1985 8 15 0 1 30.00 + .29 1.49 6 1985 8 17 0 1 20.00 + 1.09 5.59 6 1985 8 19 0 1 27.00 + 1.75 8.94 6 1985 8 28 0 1 8.00 + .00 .00 6 1985 9 14 0 1 17.00 + .00 .00 6 1985 9 15 0 1 3.00 + .00 .00 6 1985 10 8 0 1 145.00 + 70.17 67.38 6 1985 10 9 0 1 .00 - 86.03 116.43 6OHS - 23
HYDROLOGY PROJECTTechnical Assistance
COMMON ERRORS - SHIFT IN ENTRIESSpatial homogeneity check ====================================
Test station VADAGAM PH
Radius of circle of influence : 25.000 (km)
Station weights proportional to : 1/D^2.00
Admissible absolute error : 50.000 Multiplier to stdv of neighbours: 2.000
Selected neighbour stations: Quadrant Station Distance (km)
1 RAHIOL PH 12.606 1 MODASA PH 18.689 4 BAYAD PH 12.882 4 ANIOR PH 21.829
Year mth day hr si P_obs flag P_est Stdv n
1988 8 1 0 1 .50 - 8.32 3.83 4 1988 8 5 0 1 .00 - 181.97 45.70 4 1988 8 7 0 1 161.00 + 14.23 8.32 4 1988 8 8 0 1 4.00 - 11.98 3.06 4 1988 8 9 0 1 18.00 + 7.12 1.72 4 1988 8 11 0 1 4.20 + .59 1.43 4 1988 8 25 0 1 32.00 + 1.97 4.34 4 1988 9 6 0 1 9.50 + .00 .00 4 1988 9 29 0 1 12.00 + 1.09 1.30 4OHS - 24
HYDROLOGY PROJECTTechnical Assistance
Tabulation of series, Year 1988
==========Data========== Year mth day hr si ANIOR BAYAD MODASA RAHIOL VADAGAM PH PH PH PH PH
1988 7 12 .0 .0 .0 .0 .0 1988 7 13 .0 .0 70.0 .0 .0 1988 7 14 33.0 65.0 75.0 30.0 14.0 1988 7 15 8.0 17.8 12.5 5.0 3.0 1988 7 16 26.8 14.0 31.0 60.6 40.0 1988 7 17 5.4 1.2 10.0 2.0 1.0 1988 7 18 .0 2.0 .0 .0 1.0 1988 7 19 40.0 57.8 2.5 50.8 35.0 1988 7 20 54.2 46.0 60.0 32.8 46.0 1988 7 21 7.0 17.0 4.0 4.0 19.0 1988 7 22 113.0 78.4 124.0 91.8 82.0 1988 7 23 .0 11.2 15.0 6.8 16.3 1988 7 24 13.0 .0 29.0 7.4 .0 1988 7 25 8.0 14.0 43.5 35.8 23.1 1988 7 26 18.0 27.0 1.0 .0 4.2 1988 7 27 31.0 1.0 .0 3.4 1.2 1988 7 28 29.0 42.0 7.0 10.0 23.0 1988 7 29 .0 14.0 15.0 4.0 10.0 1988 7 30 13.4 .0 43.0 2.0 .0 1988 7 31 4.2 17.0 6.0 .0 .0 1988 8 1 8.0 3.0 13.0 11.4 .5 1988 8 2 4.0 .0 2.0 .0 .0 1988 8 3 .0 .0 17.0 22.0 4.0 1988 8 4 .0 1.0 1.0 .0 .0 1988 8 5 253.0 135.0 161.0 212.8 .0 1988 8 6 139.0 94.0 112.0 110.6 140.0 1988 8 7 20.0 24.0 4.0 7.6 161.0 1988 8 8 11.2 8.0 11.0 16.5 4.0 1988 8 9 9.0 8.0 9.0 4.8 18.0 1988 8 10 2.6 3.0 8.0 1.0 1.2 1988 8 11 3.5 .0 1.0 .0 4.2 1988 8 12 .0 .0 3.0 .0 3.0 1988 8 13 .0 .0 .0 .0 .0OHS - 25
HYDROLOGY PROJECTTechnical Assistance
COMMON ERRORS - ACCUMULATIONS
• RAINFALL OBSERVATIONS– TO BE MADE DAILY WITHOUT FAIL
– ABSENCE DUE TO PRACTICAL REASONS* SICKNESS
* HOLIDAY(S)/WEEKENDS
– OBSERVERS TENDENCY* DISTRIBUTE RAINFALL BASED ON OWN GUESS
* RECORD ACCUMULATED VALUE ON THE LAST DAY WITHOUT MENTIONING IT
* RECORD ACCUMULATED VALUE ON THE LAST DAY WITH PROPER REMARKS (NOT PRACTICED NORMALLY)
• DETECTION OF SUCH ERRORS– USING RECORDS OF NEARBY STATIONS
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HYDROLOGY PROJECTTechnical Assistance
Spatial homogeneity check ====================================
Test station DAKOR PH
Start date: 1995 6 1 0 1 End date: 1995 9 30 0 1
Radius of circle of influence : 25.000 (km)
Station weights proportional to : 1/D^2.00
Admissible absolute error : 50.000 Multiplier to stdv of neighbours: 2.000
Selected neighbour stations:
Quadrant Station Distance (km)
1 THASARA PH 8.252 1 VAGHAROLI PH 18.976 2 MAHISA PH 13.948 2 KATHLAL PH 22.216 2 MAHUDHA PH 22.694 2 SAVLITANK PH 23.403
Year mth day hr si P_obs flag P_est Stdv n
1995 7 15 0 1 .00 - 56.64 20.50 6 1995 7 18 0 1 .00 - 8.79 3.34 6 1995 7 19 0 1 .00 - 21.24 8.73 6 1995 7 20 0 1 .00 - 36.82 15.42 6 1995 7 28 0 1 97.50 + 18.12 13.28 6 1995 7 30 0 1 6.80 - 48.59 16.20 6OHS - 27
HYDROLOGY PROJECTTechnical Assistance
Tabulation of series, Year 1995
Year mth day hr si DAKOR KATHLAL MAHISA MAHUDHA SAVLITANK THASARA
1995 7 11 .0 7.0 10.0 1.5 27.0 9.0 1995 7 12 .0 .0 3.0 2.0 3.0 17.0 1995 7 13 .0 45.0 .0 .0 .0 .0 1995 7 14 .0 10.0 20.0 7.5 .0 7.0 1995 7 15 .0 14.0 50.0 33.5 24.0 77.0 1995 7 16 .0 .0 8.0 9.5 25.0 8.0 1995 7 17 .0 20.0 4.0 1.0 .0 22.0 1995 7 18 .0 10.0 8.0 1.0 6.0 11.0 1995 7 19 .0 23.0 20.0 43.0 27.0 16.0 1995 7 20 .0 .0 35.0 32.5 14.0 48.0 1995 7 21 .0 57.0 27.0 23.0 14.0 56.0 1995 7 22 .0 .0 6.0 7.0 4.0 .0 1995 7 23 .0 .0 4.0 12.0 2.0 27.0 1995 7 24 .0 10.0 .0 .0 .0 .0 1995 7 25 .0 11.0 10.0 3.0 6.0 3.0 1995 7 26 .0 25.0 .0 10.0 5.0 8.0 1995 7 27 .0 18.0 3.0 4.0 25.0 9.0 1995 7 28 97.5 25.0 24.0 46.0 3.0 12.0 1995 7 29 16.7 40.0 4.0 6.0 .0 .0 1995 7 30 6.8 45.0 34.0 22.0 62.0 52.0 1995 7 31 .0 10.0 3.0 13.0 39.0 9.0
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HYDROLOGY PROJECTTechnical Assistance
COMMON ERRORS - MISSED ENTRIESSpatial homogeneity check ==================================== Test station BHEMPODA PH Admissible absolute error : 40.000 Multiplier to stdv of neighbours: 2.000
Quadrant Station Distance (km)
1 MEGHARAJ PH 20.897 2 RAHIOL PH 17.898 3 ANIOR PH 4.535 3 BAYAD PH 23.253
Year mth day hr si P_obs flag P_est Stdv n
1997 6 9 0 1 9.00 + .00 .00 4 1997 6 14 0 1 3.00 + .00 .00 4 1997 6 22 0 1 20.00 + 4.79 2.38 4 1997 6 23 0 1 17.00 + 2.11 4.20 4 1997 6 25 0 1 165.00 - 205.65 33.94 4 1997 6 27 0 1 173.00 + 71.55 37.77 4 1997 7 10 0 1 .00 - 1.31 .65 4 1997 7 20 0 1 3.00 + 1.34 .65 4 1997 7 21 0 1 29.00 - 80.48 34.46 4 1997 7 26 0 1 1.00 - 12.73 4.42 4 1997 7 27 0 1 125.00 - 225.13 58.75 4 1997 7 28 0 1 280.00 - 376.98 153.43 4 1997 8 2 0 1 94.00 + 36.15 21.21 4 1997 8 8 0 1 .00 - 20.98 5.32 4 1997 8 9 0 1 .00 - 2.37 .56 4 1997 8 11 0 1 .00 - .44 .22 4 1997 8 14 0 1 .00 - 2.66 1.14 4 1997 8 19 0 1 .00 - 48.96 18.63 4 1997 8 24 0 1 .00 - 87.56 42.17 4 1997 9 11 0 1 .00 - 18.50 6.03 4 1997 9 13 0 1 .00 - 15.36 5.79 4
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HYDROLOGY PROJECTTechnical Assistance
Tabulation of series, Year 1997
Year mth day hr si ANIOR BAYAD BHEMPODA MEGHARAJ RAHIOL
1997 7 25 .0 .0 .0 1.0 .0 1997 7 26 13.0 11.0 1.0 4.0 16.0 1997 7 27 225.0 147.5 125.0 312.0 209.5 1997 7 28 420.5 194.5 280.0 32.5 60.0 1997 7 29 4.0 1.5 3.0 4.5 5.5 1997 7 30 16.5 9.0 13.0 12.0 7.0 1997 7 31 3.0 4.0 3.0 22.0 1.5 1997 8 1 290.0 257.0 275.0 192.5 129.5 1997 8 2 38.5 57.5 94.0 15.0 2.5 1997 8 3 11.5 28.5 24.0 1.0 11.5 1997 8 4 .0 .0 .0 .0 .0 1997 8 5 15.0 .0 23.0 .0 .0 1997 8 6 .0 .0 .0 .0 .0 1997 8 7 1.0 1.5 .0 1.0 .0 1997 8 8 20.5 25.0 .0 32.0 18.0 1997 8 9 2.5 2.0 .0 1.0 1.5 1997 8 10 .0 .0 .0 .0 .0 1997 8 11 .5 .0 .0 .0 .0 1997 8 12 4.0 1.0 .0 7.0 8.0 1997 8 13 2.5 6.0 .0 1.0 .0 1997 8 14 3.0 1.0 .0 .5 .0 1997 8 15 .0 .0 .0 1.0 .0 1997 8 16 .0 2.0 .0 .0 .0 1997 8 17 .0 .0 .0 .5 1.0 1997 8 18 .0 .0 .0 .0 3.0 1997 8 19 54.0 33.0 .0 12.0 7.0 1997 8 20 .0 7.0 .0 1.0 30.0 1997 8 21 1.0 .0 .0 6.5 .0 1997 8 22 .0 .0 .0 .0 .0 1997 8 23 3.0 .0 .0 9.5 19.5 1997 8 24 91.0 13.5 .0 125.5 50.0 1997 8 25 16.5 33.0 .0 11.0 31.0 1997 8 26 29.0 19.0 .0 54.5 .0 1997 8 27 2.5 5.5 .0 1.0 .0 1997 8 28 .0 .0 .0 .0 .0 1997 8 29 .0 .0 .0 .5 .0 1997 8 30 15.5 33.0 .0 .5 31.5 1997 8 31 .0 .0 .0 .0 .0
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HYDROLOGY PROJECTTechnical Assistance
DOUBLE MASS ANALYSIS• DETECTION OF SYSTEMATIC SHIFTS IN TIME
– PERSISTENCE FOR LONG TIME PERIODS
– ABRUPT OR GRADUAL CHANGE
• TEMPORAL INCONSISTENCY: FACTORS– SHIFTING OF STATION TO ANOTHER LOCATION
– CHANGE IN EXPOSURE CONDITION
– CHANGE IN EQUIPMENT OR PRACTICES
– UNATTENDED FAULT IN EQUIPMENT
– CHANGE IN REGIME: MAN-MADE TOO
• IN-HOMOGENEITY IN DATA SET– NOT ACCEPTABLE IN STATISTICAL ANALYSIS
– RELATING SERIES TO DESIRED SITE/REGIME
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HYDROLOGY PROJECTTechnical Assistance
DETECTION OF INHOMOGENEITY
• COMPARING BEHAVIOUR OF TEST STATION WITH RESPECT TO NEARBY STATIONS– BASE STATION(S) ASSUMED TO HOMOGENEOUS
– ANY SIGNIFICANT & PERSISTENT DIFFERENCES IN MUTUAL RELATIONSHIP INDICATES SHIFT
– RANDOM VARIATION IN RELATIONSHIP TEND TO COMPENSATE IF AGGREGATED IN TIME
– SYSTEMATIC VARIATION TENDS TO SHOW UP
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HYDROLOGY PROJECTTechnical Assistance
DOUBLE MASS CURVE
• SIMPLE TEST PROCEDURE– ACCUMULATE IN TIME
* OBSEREVED TEST SERIES
* ESTIMATED BASE SERIES
– COMPARE THE TWO ACCUMULATED SERIES
– SIGNIFICANT & PERSISTENT DEVIATION SHOWS IN-HOMOGENEITY IN THE TEST SERIES
i
jj
i
jj
i
X
Y
rc
1
1
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HYDROLOGY PROJECTTechnical Assistance
Double Mass Curve
Base Series (%) - (Megharaj & Bayad)10095908580757065605550454035302520151050
Tes
t Ser
ies
(%) -
(Vad
agam
)100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
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HYDROLOGY PROJECTTechnical Assistance
Double Mass Curve (1970 - 1996)
Base Series (%) - (KAPADWANJ, MAHISA, THASARA)10095908580757065605550454035302520151050
Tes
t Ser
ies
(%) -
(VA
DO
L)100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
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