FREE INSTITUTE OF SCIENCE 



VEGETATION OF SOUTH FLORIDA 



years is 53 inches, with a minimum of 40.22 inches in 1902 and a maximum 

 of 70.92 inches in 1887. If this amount of rainfall was uniformly distributed 

 throughout the year, it would not be a difficult matter to take care of it, but 

 it is excessive during the summer and fall, often exceeding 12 inches in a single 

 month. It is this period of heavy rain that must be considered in planning 

 the drainage of this section. In the months of July and August, 1905, there 

 was a total rainfall of 27.95 inches recorded at Kissimmee. During the same 

 period, there was but 20 inches at Jupiter, 24 inches at Fort Myers, and 25 at 

 Miami. This would seem to indicate that the rain at Kissimmee was increased 

 by some local influence that did not exist throughout the peninsula, and that 

 probably the rainfall over the entire drainage area did not exceed 26 inches. 

 As a fall of 26 inches in any other two consecutive months is the closest ap- 

 proach to this amount, it is safe to conclude that 26 inches is an extraordinary 

 rainfall, not likely to occur except at rare intervals, and it would hardly be 

 wise or prudent to base the carrying capacity of the drains on this amount. 

 Since a rainfall of 18 to 22 inches in two consecutive months has occurred three 

 times during the last decade, we may reasonably expect the same amount in 

 the future. In order to have a fair margin of safety in the storage capacity 

 of Lake Okeechobee, canals should be provided having sufficient discharge 

 to remove a maximum rainfall of 24 inches from the entire watershed in two 

 consecutive months." 



"From examination of the data available it appears that the amount of 

 moisture removed by a mixed growth of vegetation, such as trees, bushes, 

 and grass, is at least o.io inch per day. All the Okeechobee watershed, how- 

 ever, is covered with a thick growth of vegetation, there being numerous lakes 

 and ponds and extensive areas of almost barren soil, but if this vegetation were 

 concentrated on one-half of the area it would cover it quite densely; so, in- 

 stead of estimating the water removed by the plant growth at o.io inch for the 

 entire watershed, we will restrict it to one-half the area, as more nearly repre- 

 senting the conditions in southern Florida. Assuming 0.25 inch to be removed 

 by free evaporation and 0.05 inch by plant growth, we have 0.30 inch per day, 

 or a total of 9 inches per month taken up by these two methods. This is 75 

 per cent, of the mean rainfall for July and August, which amount agrees quite 

 closely with the results obtained in other places where careful and continued 

 experiments have been made. Since the maximum rainfall that is likely to 

 occur in July and August is 24 inches, the mean daily precipitation for these 



