DRY YEARS

Evening Star, Issue 20972, 10 December 1931, Page 16

DRY YEARS

DOMINION'S DROUGHTS MIGHT BE MUCH WORSE INTERESTING SUMMARY The present summer has started with the apparent intention of being hot and dry; indeed, some districts are already complaining of drought. Hence a memorandum on ‘ Dry Years in New Zealand,’ prepared by Ur E. Kidson, Director of Meterological Services, is of interest at the present time. .Referring to l«st year, he remarks that 1930 was a very "dry year, and at various rimes and in different districts considerable inconvenience and even financial loss resulted. In particular, hydroelectric schemes, especially in the South Island, suffered from unprecedented shortage of water. “It is interesting, therefore, to discover what the rainfall deficiencies amounted to and how they compared with those in other dry years. From about 1864 to 1880 rainfall was recorded at quite a number of stations in New Zealand, but between 1831 and 1893 the records wore extremely few in number. From 1894 onwards an increase commenced, but it was not until about 1900 that observers became sufficiently numerous and well distributed to enable charts showing the distribution of rainfall over the whole dominion to bo drawn. Nevertheless, it seems certain that none of the earlier years, as far back at least as 1864, was as dry as 1914. Over most of the North Island the rainfall deficiencies in 1914 exceeded lOin. Indeed, for the North Island as a whole, and especially for the Auckland province, 1914 was undoubtedly' the driest year hitherto recorded. It was also very dry in Nelson and Marlborough. In Canterbury conditions were much more nearly normal, while in Otago a. large area received more than the average rain. On the west coast of the South Island, though tho rainfall was below average, tho departures did not amount to a largo percentage of tho annual falls'. AUSTRAHA'S DROUGHT. It is a very interesting fact, says Dr Kidson, that in 1914 Australia suffered from tho severest drought in its history. Tho characteristic of the year was that storm systems' wore very poorly developed, and there was a relative absence of the northerly winds which bring warm, moist air from low latitudes. It is this air of a northerly origin that is the source of most of our heavy rain, and in tho Auckland province this is especially the case. Westerly winds were fairly strong, which accounts for the shortage being less important about Capo JCgmont and in western districts of the South island. There were heavy rains in these areas in autumn and spring, the periods when the westerlies are at their strongest. The altitude of the ranges is so great that heavy rains are caused by tho cooling due to uplift of the air that is forced over them, even if it is initially dry. In Canterbury and Otago most of the rain comes from south-westerly winds. Tho year 1914 followed a very pronounced sunspot minimum. In Australia tho drought broke in 1915. Depressions gradually became more vigorous, and a very wet period, which continued through 1916 and 1917, commenced. In Now Zealand the changes were similar in kind, but occurred somewhat later; 1915 was still dry over most of tho North Island, but become wet on the west coast of the South Island. The most important feature of the year, however, was that eastern districts experienced a very dry time. In Marlborough and most of Canterbury it was much more severe than any recorded either before or since. Tho principal characteristic of the weather in 1915 was the strong development of tho anti-cyclones, many of which crossed New Zealand. Cyclones were few in number, and moved rather fast, and there was a relative absence of southerly winds. Rainfall was below norma! at many places in 1912 and 1913, and there is no doubt that tho period from 1912 to 1915 was tho driest experienced in the dominion. Tho next very dry year was 1919. There was little to elioo.se between it and 1914 for dryness so far as the ■ North Island was concerned. Tho northern portion of the South Island also was drjf, but over tho southern half tho rainfall was mainly above normal. The year 1919 appears to have been similar to 1915 in that the cyclones that crossed New Zealand were few in number and not very vigorous. A good deal of anti-cyclonic weather was experienced also. There was, however, much more westerly and south-westerly wind over the South Island, depressions of tho westerly type being fairly well developed in tho south, but having poor northward extensions. in Australia, though tho drought was not so general ns in 1914, in Victoria and New South Wales it was extremely severe. DRY YEARS AND SUN SPOTS. For the country as a whole 1930 proved to be the driest year of all. This, was especially tho case with regard to tho western of tho South Island. It is not surprising that tho Lake Coleridge hydro-electric scheme suffered severely. The year was as dry as any of the earlier ones also in eastern districts north of Hawke’s Bay towards East Cape. Otherwise'tho North Island did not suffer so severely as in 1914 and 1919. A few heavy and rather local falls raised the totals very considerably in Taranaki, so that tho deficits were not especially large there. Small areas about Auckland and in southern Hawke’s Bay, most of the Canterbury Plains, and a part of southern Otago had rather more than tho average falls. Both 1919 and 1930 followed sun spot maxima by about two year . Now Zealand seems to be liable to a very dry spell at about this time. As regards the typo of weather, the two years were very different. Cyclones were numer- ■ oiis in 1930, and tho weather was stormy. Tho westerly wind drift was, however, unusually weak. There were few of tho pronounced type of V-do-pression which has a well-developed trough extending in a northerly direction, and which tends to bring general rains to Now Zealand. Tho year 1930 differed from tho other years in that it was a wet year in Australia, although a series of dry years had preceded it. Each of tho years mentioned above was cold, except 1915, which was very slightly warmer than usual. ‘ NEW ZEALAND LUCKY, When New Zealand has a dry year the effects are not so disastrous as the effects of a drought in Australia, for instance. “Tho strength of New Zealand’s position from a climatic point of view,” remarks Dr Kidson on the point, “ is well illustrated by her experiences in these, the driest years she has experienced. In none of them did tho primary producer suffer anything approaching disaster. Taking tho country as a whole, 1930 was a good year for the man on the land. Losses, certainly, were experienced in some districts, but in others conditions wore unusually favourable. We are fortu-

uatc in having largo areas which receive about tho optimum amount of rainfall for the growth of good pastures. In the. areas of low rainfall the reliability is high, and a largo part falls in spring and summer, when it is most needed. Again, there is a teir 1 . ey for variations in tho eastern d.’ftricts of the South Island, which contain some of our richest country, to bo opposite in character to those in tho remainder of tho dominion,”-