284 Transactions. — Gcolor/y. 



The average rainfall for Hawke's Bay is given in Dr. Hector's 

 " Handbook" as 36 inches, and for Napier 37-200 inches. The 

 latter is the average of twelve of the years between 1860 and 

 1881, no rainfall being given for the years 1807-09 and 1881. 

 As far as I can gather from the statistics of rainfall already 

 published, this district has suffered from a diminished rainfall 

 at regularly recurring periods. In 1800 there was a deficiency 

 in the rainfall of 7-260 inches ; in 1872, or six years later, the 

 deficiency was 13-320 inches ; in 1878, or six years later, the 

 deficiency was 10-100 inches ; whilst during the year ended 

 March last, or say eight years later, the deficiency was actually 

 21 inches on the Heretaunga Plain, and 20-200 inches at 

 Napier ! It is curious that in each year succeeding what might 

 appropriately be termed the "drought year," there was an 

 excess of rainfall, so that, during the present year, we may 

 expect, if not floods, certainly many rainy days to make up for 

 the unusual deficiency in the rainfall of the past year. 



Now if we consider the Heretaunga Plain and the slopes of 

 the hills which naturally drain their surplus waters into it as 

 containing 100,000 acres, we may readily compare the quantity 

 of water that fell within this area last year with the quantity 

 that should have fallen to supply the ordinary requirements of 

 the district, had the normal rainfall been maintained. 



The weight of an inch of rainfall over an acre of ground may 

 be stated roughly as 100 tons. Actually it is 101^ tons : for 

 30 inches of rainfall, the weight on an acre, amounts to 3,000 

 tons. This is the quantity of rain that should have fallen last 

 year on every acre of land on the Heretaunga Plain. The 

 quantity that actually fell was 1,500 tons. On the 100,000 

 acres which I have assumed to constitute the drainage area of 

 the plains, 150,000,000 tons of water fell last year, whilst 

 300,000,000 tons ought to have fallen had the average rainfall 

 for the year been maintained. Thus the year's deficiency was 

 210,000,000 tons, or a quantity represented by no fewer than 

 47,000,000,000 gallons. I estimate that, under ordinary con- 

 ditions of soil and temperature, an inch of rainfall would moisten 

 the ground for a depth of inches, that is supposing no portion 

 of it was allowed to pass away either by evaporation or by 

 drainage in the way of surplus soakage. Consequently, 15 

 inches of rainfall would moisten the ground to a depth of 90 

 inches, or 7 feet inches. At this depth it may be said that 

 the ground is generally moist and damp. It is evident, there- 

 fore, that, without considering the question of bedding, the 

 district under notice had no surplus soakage last year to maintain 

 the artesian supply, which I have already pointed out amounts, 

 at the lowest possible estimate, to 8,884,000,000 gallons per 

 annum ; and either the supply was the accumulation of previous 

 years of soakage, or it is obtained from some outside source. I 



