Abstract
MR. W. R. BALD WIN-WISEMAN, lecturer in hydraulics in the University of Western Australia, writing in reference to our leading article of August 4 on the “Government and Inland Water Survey”, emphasises the need for an organised hydrographic service, and instances the Hydrographic Survey of the Po as one of the most efficient services in the world. From analyses of many lengthy records of rainfall in his possession, he contends that there is little justification in many cases, and no justification in some, for the assumption that any 35-year-mean approximates fairly closely to the true mean, or that a 20 per cent deficiency adequately represents the average annual deficiency of the three driest years in a lengthy rainfall record. Consequently, water works planned on these assumptions may make a too generous allocation of compensation water, while making inadequate provision for a storage sufficient to tide over the contingencies arising from a pro longed, or frequently recurrent, drought. He goes on to point out that Dr. E. Huntington has demon strated the existence of a climatic pulse of about 640 years, which is probably a multiple of the sun-spot period of 11.2 years (57 x 11.2 = 638.4); if A.D. 1372, the year of maximum sunspot activity in the Chinese record, which has now been unofficially maintained for nearly a thousand years, be taken as a nodal point in this pulse, previous points will have occurred about 543 B.C., A.D. 95, and A.D. 734—all four points being in periods of notorious aridity. If the sequence is maintained, the next occurrence may be expected about A.D. 2010, with a prevalence of drought conditions, either prolonged or frequently recurrent, towards the close of the present century.
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Rainfall Records and Drought Periodicity. Nature 134, 656 (1934). https://doi.org/10.1038/134656b0
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DOI: https://doi.org/10.1038/134656b0