Measurement of Precipitation Above Forest Canopies

Determination of the precipitation-run-off relationship, and of the conditions governing it in areas under various types of forest cover, is becoming the focus of much attention by conservation workers in an effort toward better coordination of land management practices for regulation of water yield, control of floods, and reduction of erosion. The interception of rainfall by the forest canopy is undoubtedly responsible for some of the regulating and reducing effect that forests are known to exert on run-off. This paper discusses the degree to which interception of rainfall by the forest canopy may modify the run-off relationship, and presents a method by which rainfall may be measured at the tree crown surfaces in order that true values will be established in the determination of the role of forest cover in controlling run-off.