The Pamphlet Collection of Sir Robert Stout: Volume 66
Rainfall
Rainfall.
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I. Review of the Proportions of Rain in New Zealand.
Stations. | Dec. | Jan. | Feb. | Mar. | April | May | June | July | Aug. | Sept. | Oct. | Nov. |
---|---|---|---|---|---|---|---|---|---|---|---|---|
N. Island. | ||||||||||||
Mongonui | 2.339 | 3.209 | 7.787 | 1.492 | 2.882 | 5.461 | 8.319 | 6.598 | 6.241 | 5.831 | 3.701 | 4.272 |
Auckland | 3.409 | 2.071 | 3.272 | 3.150 | 3.402 | 4.771 | 5.721 | 5.279 | 4.331 | 4.331 | 3.520 | 3.752 |
Taranaki | 4.921 | 3.221 | 3.908 | 2.579 | 3.520 | 7.720 | 5.914 | 6.299 | 5.177 | 5.252 | 5.969 | 4.858 |
Napier | 5.630 | 3.571 | 3.650 | 1.130 | 1.358 | 1.532 | 3.402 | 3.681 | 6.870 | 2.414 | 1.539 | 1.201 |
Wellington | 3.999 | 3.882 | 4.453 | 3.780 | 3.280 | 4.540 | 5.212 | 5.658 | 4.299 | 3.941 | 5.000 | 3.500 |
S. Island. | ||||||||||||
Nelson | 4.319 | 5.358 | 8.331 | 2.063 | 3.221 | 6 177 | 4.441 | 6.319 | 6.233 | 6.319 | 5.000 | 4.815 |
Hokitika | 12.169 | 8.902 | 9.871 | 6.752 | 8.611 | 6.370 | 8.240 | 9.638 | 9.130 | 5.878 | 13.402 | 12.690 |
Bealey | 14.087 | 9.681 | 8.902 | 3.921 | 7.433 | 8.079 | 5.019 | 10.378 | 7.799 | 5.811 | 15.501 | 8.733 |
Christchurch | 1.622 | 2.311 | 2.370 | 1.752 | 1.811 | 2.280 | 3.189 | 2.449 | 2.319 | 1.161 | 2.142 | 2.130 |
Dunedin | 3.012 | 3.599 | 21.42 | 2.220 | 2.122 | 3.949 | 2.441 | 2.500 | 2.228 | 2.000 | 2.500 | 2.969 |
Southland | 3.622 | 5.279 | 3.921 | 3.980 | 3.571 | 5.401 | 5.019 | 3.441 | 4.390 | 2.661 | 3.929 | 4.520 |
The fluctuation in the annual rainfall at the principal stations is shown in the following table :—
Stations. | Means for each Year, and Difference from General Average. | ||||||
---|---|---|---|---|---|---|---|
North Island. | 1866. | 1867. | 1868. | 1869. | 1870. | 1871. | 1872. |
Auckland | 42.000 | 53.180 | 49.087 | 52.797 | 44.831 | 47.505 | 42.096 |
−3.306 | 7.874 | +3.781 | +7.491 | .475 | +2.199 | −3.210 | |
Taranaki | 55.700 | 60.690 | 50.420, | 55.125 | 54.720 | 72.120 | 63.640 |
−2.384 | +2.606 | −7.664 | −2.959 | −3.364 | +14.036 | +5.656 | |
Napier | 30.000 | 32.850 | 35.890 | 23.940 | |||
−7.260 | −4.410 | −1.370 | −13.320 | ||||
Wellington | 41.100 | 41.950 | 55.522 | 56.768 | 48.205 | 64.057 | 50.945 |
−9.681 | −8.831 | +4.741 | +5.987 | −2.576′ | +13.276 | +.164 | |
South Island. | |||||||
Hokitika | 127.500 | 110.510 | 120.210 | 88.210 | 116.680 | 122.440 | 123.210 |
+15.344 | −1.646 | +8.054 | −23.946 | +4.524 | +10.284 | +11.054 | |
Christchurch | 19.400 | 30.070 | 30.041 | 27.292 | 28.364 | 27.935 | 19.741 |
−6.374 | +4.296 | +4.267 | +1.518 | +2.590, | +2.161 | −6.033 | |
Dunedin | 29.000 | 39.050 | 33.893 | 32.918 | 39.202 | 22.146 | 27.393 |
−3.019 | +7.031 | +1.874 | +.899 | +7.283 | −9.873 | −4.626 | |
Southland | 47.200 | 41.620 | 46.346, | 42.680 | 53.950 | 39.030 | 40.110 |
+3.526 | −2.054 | +2.672 | −.994 | +10.2761 | −4.644 | −3.564 |
North Island. | 1873. | 1874. | 1875. | 1876. | 1877. | 1878. |
---|---|---|---|---|---|---|
Auckland | 41.237 | 35.024 | 51.310 | 44.025 | 40.375 | 37.160 |
−4.069 | −10.282 | +6.004 | −1.281 | 4.931 | −8.146 | |
Taranaki | 53.120 | 57.220 | 66.960 | 48.180 | 52.000 | 56.730 |
−4.964 | −.864 | +8.876 | −9.924 | −6.084 | −1.354 | |
Napier | 42.380 | 37.940 | 38.260 | 38.390 | 33.450 | 21.100 |
−5.120 | +.680 | +1.000 | +1.130 | −3.810 | −16.160 | |
Wellington | 54.985 | 53.496 | 65.827 | 43.374 | 51.925 | 54.602 |
+4.204 | +2.715 | +16.046 | −7.401 | +1.144 | +3.821 | |
South Island. | ||||||
Hokitika | 96.170 | 104.480 | 130.790 | 116*325 | 136.660 | 154.446 |
−5.986 | −7.676 | +18.634 | +4-169 | +24.504 | +42.290 | |
Christchurch | 26.330 | 22.790 | 32.310 | 23-990 | 23.720 | 13.540 |
+.556 | −2.984 | +6.536 | −1-029 | −2.054 | −12.234 | |
Dunedin | 35.825 | 28.739 | 42.631 | 38-260 | 37.460 | 45.235 |
+3.806 | −3.280 | +10.612 | +5-586 | +5.441 | +13.216 | |
Southland | 37.480 | 44.650 | 44.180 | 43.150 | 54.020 | |
−6.194 | +.976 | +.506 | −.524 | +10.346 |
North Island. | 1879. | 1880. | 1881. | 1882. | 1883. | 1884. |
---|---|---|---|---|---|---|
Auckland | 46.130 | 38.890 | 34.237 | 45.630 | 52.215 | 38.070 |
+.824 | −6.416 | −11.069 | +.324 | +6.909 | −7.236 | |
Taranaki | 60.180 | 47.220 | ||||
−2.096 | −10.864 | |||||
Napier | 53.140 | 38.400 | ||||
+15.880 | +.140 | |||||
Wellington | 57.441 | 46.767 | 50.132 | 55.685 | 51.994 | 62.335 |
+6.660 | −4.014 | −.649 | +4.904 | +1.213 | +11.554 | |
South Island. | ||||||
Hokitika | 128.295 | 122.840 | ||||
+16.139 | +10.684 | |||||
Christchurch | 23.180 | 17.670 | *28.071 | 25.391 | 30.336 | 28.451 |
−2.594 | −8.104 | +2.297 | −.383 | +4.562 | +2.677 | |
Dunedin | 42.099 | 33.063 | 26.402 | 41.796 | 38.312 | 33.881 |
+10.080 | +1.044 | −5.617 | +9.777 | +6.293 | +1.862 | |
Southland | 33.260 | 39.140 | ||||
−10.4141 | −4.534 |
* Station moved from Christchurch to Lincoln, Canterbury.
North Island. | |
---|---|
Auckland | 45.306 |
Taranaki | 58.084 |
Napier | 37.260 |
Wellington | 50.781 |
South Island. | |
---|---|
Hokitika | 112.156 |
Christchurch | 25.774 |
Dunedin | 32.019 |
Southland | 43.674 |
The observations that have been taken show that the northern part of New Zealand is within the influence of the subtropical winter rainfall, the probability of rainfall in winter in that part of the colony being twice as large as in summer.
In the south, however, the rainfall, though irregular, is distributed more equally over the year. The chief difference to be observed is that on the west coast spring rains prevail, and summer rains on the east coast; while in the middle of the colony the driest season is autumn, and in the south it is the winter and spring.
The contrast between the rainfall on the east and west coasts, as with the temperature, is most striking. Thus, in the North Island, Napier on the east has only half the amount of rain that falls in Taranaki on the west. But the South Island, with its longitudinal range of lofty mountains, exhibits this feature in a still more marked manner, for the rainfall on the west is nearly five times greater than that on the east. The excess of precipitation on the coast is clearly illustrated by the distribution of the glaciers on the opposite sides of the range. Those on the west slope have an excessive supply of snow, and descend to a line where the mean annual temperature is 50° Fahr., while on the east slope they descend only to the mean annual temperature of 37°. The winter snow-line on the Southern Alps on the east side is 3,000ft., and that on the west side is 3,700ft.
The distribution of the rainfall in different parts of the Islands is best expressed by an approximate statement of the hydraulic discharge from the various drainage-areas. The average rainfall, and the percentage allowed for evaporation and soil-absorption, have been estimated for each area from such information as is available, but must only be accepted as provisional.
Schedule of the Principal Rivers in New Zealand, showing approximately the Areas of Watersheds, the Average Annual Rainfall, and Discharge for each.
Rivers. | Area. | Average Rainfall. | Estimated Discharge per Minute. | Remarks. |
---|---|---|---|---|
North Island. | Sq. Miles. | Inches. | Cubic Feet. | |
Waikato | 4,768 | 40 | 839,168 | |
Kaipara | 2,622 | 47 | 545,376 | |
Wanganui | 2,525 | 47 | 525,200 | |
Manawatu * | 2,239 | 65 | 642,593 | |
Thames | 1,779 | 48 | 377,148 | Including Piako. |
Rangitaiki | 1,033 | 30 | 215,556 | Have a common embouchure in a coastal lagoon. |
Whakatane | 1,014 | 35 | 156,156 | Have a common embouchure in a coastal lagoon. |
Rangitikei | 1,435 | 50 | 315,700 | |
Wairoa | 1,303 | 45 | 257,994 | |
Mohaka | 1,034 | 45 | 204,732 | |
Ngaruroro | 843 | 40 | 148,368 | Might be concentrated on Napier Harbour. |
Tutaekuri and Esk | 487 | 35 | 73,998 | Might be concentrated on Napier Harbour. |
Tukituki | 815 | 35 | 125,510 | |
Mokau | 815 | 60 | 215,445 | |
Patea | 622 | 55 | 151,146 | |
Waipaoa, Poverty Bay | 602 | 30 | 80,066 | Partly combine in floods. |
Gisborne | 75 | 35 | 11,550 | Partly combine in floods. |
Hokianga | 560 | 50 | 123,760 | |
Waiapu | 505 | 40 | 88,880 | |
Waitara | 501 | 56 | 123,747 | |
South Island. | ||||
Clutha | 8,248 | 30 | 1,088,736 | |
Waitaki | 4,730 | 26 | 539,220 | |
Waiau (South) | 3,079 | 41 | 557,299 | |
Mataura | 2,378 | 30 | 316,274 | |
Buller | 2,341 | 95 | 990,897 | |
Taieri | 2,317 | 37 | 379,988 | |
Grey | 1,572 | 90 | 624,084 | |
Wairau | 1,562 | 35 | 240,548 | |
Oreti | 1,422 | 40 | 250,272 | |
Waimakariri | 1,922 | 55 | 345,546 | |
Rakaia | 1,401 | 50 | 308,220 | |
Rangitata | 752 | 48 | 159,424 | |
Selwyn (Lake Ellesmere) | 718 | 30 | 94,776 | |
Jacob's | 633 | 40 | 111,408 | |
Haast | 412 | 125 | 227,424 | |
Kaduka (Martin's Bay) | 283 | 127 | 158,480 | |
Hokitika | 382 | 120 | 202,460 | |
Oamaru Creek | 23 | 22 | 2,231 | |
Milford Lagoon and Opihi | 888 | 28 | 109,224 |
Periods of lasting drought are almost unknown in New Zealand, and only in two instances do the records show a whole month at any station without rain. The greatest day's rain recorded is 6½in. at Auckland, and 9½in. in Nelson. Similar heavy showers occur at the north-west stations, where the general average shows 70in. in eighty-five days' in the year. The opposite extreme is on the south-east, where 34in. fell in 180 days.