1. CORRECTION/COMPLETION OF RAINFALL DATA PRIMARY & SECONDARY VALIDATION –FLAGGING : SUSPECT OR INCORRECT VALUES –MISSING : NON-OBSERVANCE OR LOSS OF DATA ESTIMATE - SAME/NEIGHBOURING STATIONS –WHERE POSSIBLE *INCORRECT DATA TO BE CORRECTED *MISSING DATA TO BE COMPLETED (FILLED-IN) –IF NOT POSSIBLE *SUSPECT DATA WILL BE RETAINED AS FLAGGED *INCORRECT DATA TO BE SET AS MISSING *MISSING VALUES LEFT AS SUCH OHS - 1

2. CORRECTION/COMPLETION OF RAINFALL DATA PROCEDURE TO BE EMPLOYED –TYPE OF ERROR –AVAILABILITY OF SUPPORTING DATA FOR ESTIMATION DONE AT SDPCs/RDPCs –DATA VALIDATION REPORT FROM DDPCs OHS - 2

3. CORRECTION/COMPLETION PROCEDURES ARG/SRG DATA AT ONE OR MORE STATIONS CORRECTING TIME SHIFT IN DATA APPORTIONING ACCUMULATIONS ADJUSTING DATA FOR LONG TERM SHIFT *DOUBLE MASS ANALYSIS SPATIAL INTERPOLATION *ARITHMETIC AVERAGE *NORMAL RATIO *NEAREST NEIGHBOUR OHS - 3

4. SRG SUSPECT/FAULTY - ARG AVAILABLE OHS - 4

5. ARG MISSING/FAULTY - SRG AVAILABLE ARG RECORD NOT AVAILABLE *FAULT IN EQUIPMENT / RECORDING MECHANISM *CHART/DATA MISSING SRG RECORD AT STATION AVAILABLE HOURLY DISTRIBUTION *SIMILAR TO NEIGHBOURING STATIO(S) OHS - 5

6. OHS - 6

7. OHS - 7

8. CORRECTING TIME SHIFT OHS - 8

9. APPORTIONING ACCUMULATED RAINFALL DATA VALIDATION –ACCUMULATION INDICATED *AMOUNT OF ACCUMULATION *PERIOD OF ACCUMULATION CORRECTION –ESTIMATE BY SPATIAL INTERPOLATION –APPORTIONING REPORTED ACCUMULATION PROPORTIONATELY OHS - 9

10. ESTIMATE - SPATIAL INTERPOLATION APPORTIONING ACCUMULATED TOTAL OHS - 10

11. ACCUMULATION INDENTIFIED OHS - 11

12. APPORTIONING ACCUMULATION OHS - 12

13. ADJUSTING LONG TERM SHIFTS - DOUBLE MASS ANALYSIS SLOPE  1 SLOPE  2 ADJUSTED OHS - 13

14. DATA CORRECTION OHS - 14

15. RESULTS - DOUBLE MASS ANALYSIS OHS - 15

16. DATA ADJUSTED OHS - 16

17. SPATIAL INTERPOLATION ARITHMETIC AVERAGE –ANNUAL AVERAGE WITHIN 10% NORMAL RATIO METHOD OHS - 17

18. NEAREST NEIGHBOURHOOD METHOD (DISTANCE POWER) + + + I III IV + Neighbouring stations Test station Selected neighbouring stations II etc. Quadrant II + + + + + + + + + + + + + OHS - 18

19. OHS - 19

20. COMPUTATION OF STATION WEIGHTS OHS - 20

21. OHS - 21

22. COMPARISON OF OBSERVED & ESTIMETED OHS - 22

23. CORRECTION FOR HETEROGENEITY STATION NORMALS –HISTORICAL RECORDS –RELATIONSHIP WITH ELEVATION OHS - 23