MEMO
Floods in the extreme NW Cape
22 May 2006
It was fascinating to see the floods in the extreme NW Cape on TV yesterday. The heaviest rainfalls
in this area occurred in June 1925 when 114 mm was recorded in the SAWS rainfall District 1. The
heaviest country-wide rainfall over South Africa as a whole occurred three months earlier in March
1925. If you look at Figure 5.2 in Chapter 5 of my technical report, the return periods for the June
1925 rainfalls for Districts 1,2,3,4,6 and 7 were as follows:
District
Return period (years)
1
>100
2
>100
3
50-100
4
20-50
5
(no data)
6
>100
7
2-10
This was far and away the heaviest rainfall in this region to date.
For those who may be interested, the following table shows the statistical analyses of the annual
data for District 1. Note that the ten highest rainfalls all occurred before 1964, which confirms my
conclusions that there has been no increase in floods that could be associated with global warming.
I have got apple boxes full of rainfall calculations and coloured rainfall maps, which could provide
climatologists with valuable insights into linkages between climate and rainfall, instead of carrying
on with the futile global warming analyses, which I assure you is slowly disintegrating.
The remaining chapters of my technical report will provide the proof.
Regards
Will
DISTRICT NR 1: ANNUAL RAINFALL
SEQUENTIAL DATA
start
cont'd
Year
mm Year
21/22 134
57/ 58
22/23 188
58/ 59
23/24
75
59/ 60
24/25 307
60/ 61
25/26 102
61/ 62
26/27 135
62/ 63
27/28
86
63/ 64
28/29 153
64/ 65
29/30 215
65/ 66
30/31 137
66/ 67
31/32 152
67/ 68
mm
117
213
89
253
248
248
99
105
107
154
110
I
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RANKED DATA
start
Rank mm
1 330
2 307
3 300
4 253
5 248
6 248
7 245
8 241
9 233
10 228
11 222
Year
40/ 41
24/ 25
53/ 54
60/ 61
62/ 63
61/ 62
56/ 57
51/ 52
52/ 53
38/ 39
85/ 86
cont'd
Rank mm
37
148
38
145
39
140
40
139
41
138
42
138
43
137
44
137
45
135
46
134
47
131
Year
88/ 89
35/ 36
89/ 90
39/ 40
80/ 81
46/ 47
81/ 82
30/ 31
26/ 27
21/ 22
79/ 80
32/33
33/34
34/35
35/36
36/37
37/38
38/39
39/40
40/41
41/42
42/43
43/44
44/45
45/46
46/47
47/48
48/49
49/50
50/51
51/52
52/53
53/54
54/55
55/56
56/57
162
202
220
145
153
105
228
139
330
177
206
202
196
170
138
122
100
170
203
241
233
300
213
209
245
68/ 69
69/ 70
70/ 71
71/ 72
72/ 73
73/ 74
74/ 75
75/ 76
76/ 77
77/ 78
78/ 79
79/ 80
80/ 81
81/ 82
82/ 83
83/ 84
84/ 85
85/ 86
86/ 87
87/ 88
88/ 89
89/ 90
90/ 91
91/ 92
92/ 93
84
98
107
115
71
180
117
177
200
79
78
131
138
137
185
79
168
222
152
124
148
140
127
-1
0
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12 220
13 215
14 213
15 213
16 209
17 206
18 203
19 202
20 202
21 200
22 196
23 188
24 185
25 180
26 177
27 177
28 170
29 170
30 168
31 162
32 154
33 153
34 153
35 152
36 152
Statistical properties : natural data (mm)
Median annual rainfall 152
Mean annual rainfall 161
Standard deviation
60
Coeff. of variation
0.37
Skewness coeff.
0.64
Statistical properties : log(10) transformed data
Mean annual rainfall 2. 178 ( 151 mm)
Standard deviation 0. 162
Coeff. of variation
0.07
Skewness coeff.
-0.09
34/ 35
29/ 30
58/ 59
54/ 55
55/ 56
42/ 43
50/ 51
43/ 44
33/ 34
76/ 77
44/ 45
22/ 23
82/ 83
73/ 74
75/ 76
41/ 42
49/ 50
45/ 46
84/ 85
32/ 33
66/ 67
36/ 37
28/ 29
86/ 87
31/ 32
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
127
124
122
117
117
115
110
107
107
105
105
102
100
99
98
89
86
84
79
79
78
75
71
-1
0
90/ 91
87/ 88
47/ 48
74/ 75
57/ 58
71/ 72
67/ 68
70/ 71
65/ 66
64/ 65
37/ 38
25/ 26
48/ 49
63/ 64
69/ 70
59/ 60
27/ 28
68/ 69
83/ 84
77/ 78
78/ 79
23/ 24
72/ 73
91/ 92
92/93