110 



Division of Hydrography 



Honoliilii, Hawaii, February 12, 1916. 



Board of Commissioners of Ao-riculture and F"orestrv, Hono- 

 lulu, T. H. 



Gentlemex: — The following report of operations of the Divi- 

 sion of Hydrography during January. 1916, is submitted: 



WEATHER COXDITIOXS. 



The rainfall for the month was very heavy, auvl a heavy 

 "Kona" storm which lasted from the 16th to the 19ch caused 

 much damage and a loss of 14 lives in the lao \'alley, on ^laui. 

 The rainfall in Honolulu exceeded all available records (1877 to 

 date) for intensity and total quantity for any month. At the 

 Xuuanu Pali the rainfall for the month was 31.2 inches, while 

 between the 18th at 8:45 a. m. and the 19th at S :2S p. m., a total 

 of 33 hours, the rainfall amounted to 8.6 inches. In the upper 

 lao A'allev the rainfall was about 30 inches on the 17th, 18th and 

 19th, and it is probable that at least half of this fell within 24 

 hours. 



The large upper reservoir in Xuuanu A'alley was filled to a 

 point beyond all previous records, and on the last day of the 

 month was approximately three-fourths full. All other reser- 

 voirs on Oahu were filled to overflowing. 



The underground water supply also received an immense in- 

 crease. The water level in the wells in the city, which were being 

 pumped, rose, at some places, about three and one-half feet, while 

 in the Pearl Harbor basin, where little pumping was done, the 

 underground water level rose as much as six feet. The outflow 

 from the north portal of the Waiahole tunnel also increased 

 about a million gallons per day. 



FLOODS. 



The heavy rainfall resulted in the heaviest floods ever recorded 

 by this oflice on nearly all of the Oahu and ]Maui streams. 



In the immediate vicinity of Honolulu, the ]\Ianoa stream at 

 an elevation of 32S feet above sea level, in the upper ]\Ianoa 

 A'allev reached a maximum rate of flow of 282 million gallons 

 per dav.on two days — the 8th and 18th. 



On the X^uuanu stream at a point below the spillway of Reser- 

 voir No. 2, the flow exceeded 210 million gallons per dav on 

 the 18th. 



The flood flow of the Kalihi streani at an elevation of about 

 500 feet above sea level reached 296 million gallons per day on 

 January 25. The recording instrument on this stream was out 



