RAINFALL 255 



annum may mean that the rubber trees get the benefit of only 

 45 to 50 inches, as the most of the rain promptly finds its way 

 into the drains. In such cases, breaking up the ground by 

 chankolling it over is followed by immediate benefit to the trees. 

 For all practical purposes the rainfall is thus at once doubled, 

 or nearly doubled. Chapter and verse could be cited of estates 

 where this has been found to be the case, but it is not always 

 advisable to give names. 



One inch of rainfall on i acre of land represents 3630 cubic 

 feet of water. When, say, 5 inches of rain fall during the 

 course of twenty-four hours, as is not very uncommon, there is 

 a very large volume of water to be discharged. There are, of 

 course, in certain districts in Ceylon and India, occasions where 

 the rainfall is as high as 18 inches in twenty-four hours. Taking, 

 however, a more ordinary rainfall, such as 5 inches in twenty- 

 four hours, the rivers of water that result are a severe test of an 

 estate's drainage arrangements. On a hilly estate, unless very 

 well terraced, or protected with belts of grasses and the growth 

 of light weeds, the wash of surface-soil is very great. On a flat 

 estate, unless well drained, the flooding which ensues may 

 involve wading for a week. 



The effects of a rare, occasional flood on a low-country estate 

 generally soon pass off without much damage being done, but 

 a constantly water-logged soil is ruinous to rubber. 



Rainfall records should not only state the amount of the 

 rainfall on each day of the year, but whether the rain fell during 

 the forenoon or in the afternoon. A heavy rainfall during the 

 early hours of a day means the loss of the day's tapping. In the 

 afternoon a heavy continued shower does not interfere with this 

 work. In this way the average number of days available for 

 tapping during the year may be ascertained and checked. 



