428 



REPORT or OFFICE OF EXI'KIU MFNT STATIONS. 



A comparison of I ho ofFoct of heavy and h^ht storms, respectively, 

 may be made from the following table, which jjjives the daily rainfall 

 and run-off record from June to October, inclusive, for the Wills- 

 wood plantation, as well as the correspondinjj^ hei<^hts of water in 

 the reservoir canal. 



Exc('|i(iii<^ as affcited for short periods by rains and by jjiiinpini;, the hoip:ht of 

 water in the reservoir canals represents fairly accurately the heij,'ht of ground water 

 of the lower lands. This is notably true of the Willswood tract, where the hnvlands 

 are porous and allow a quick adjustment of water level following a change in level 

 in the canals. As an indication of the effect of evaporation, inrluding the transpira- 

 tion of the vegetation, the reeord for the month of July, as shown in the table below, 

 is especially interesting. The month was begun with the soil well moistened by 

 showers late in June, yet, with a precipitation of 1.17 inches from July 1 to 19 there 

 was a rise of only 2^ inches in the reservoir, while from July 5 to 19, with a precipita- 

 tion of 0.99 inch, there was an actual lowering of the water level in the canal. 



Daily rainfall and run-off, Willswood plantation fi 



a Taken from report by A. M. Shaw. 



A few records of pumping operations are available, covering a 

 greater length of time than those given above, but the lack of essen- 

 tial details makes them of little value for the purpose of the calcula- 

 tion of run-off. An approximate idea can be gained, howeA^er, as to 

 the amount of pumping necessary in order to maintain the water 



