Urban Rainfall Interception of Evergreen and Deciduous Trees for the Southeastern United States

Rainfall interception by tree canopies continues to gain interest amongst stormwater management professionals for green infrastructure. Field observations examined variances in interception processes for numerous species for the southeastern U.S. Knowledge gaps for urban rainfall interception specific to the southeastern U.S. describe the need for standard throughfall collection methods, a general lack of information for common species, and a weak understanding of differences in evergreen and deciduous trees. Parallel experiments at six sites were compared for evergreen and deciduous trees during 235 total rains for the first hypothesis. Paired T-tests revealed that mean throughfall for evergreens was significantly less (greater interception) (P<0.001) than for deciduous trees. Full factorial analysis including rain depth, windspeed, and leafless period, indicated that all factors were significant in affecting interception. One-way ANOVA tests comparing the four sites found no statistical difference in the deciduous (P=0.11) or evergreen (P=0.28) species, allowed combining the data for subsequent hypothesis testing. Lognormal linear regressions of throughfall vs. rainfall provide insight into expected throughfall for both tree types and for each species. It is like that the heavy bark and porous properties for evergreen play a significant role in rainfall interception.Throughfall for four street trees of different sizes across 33 rainfall events was observed for the second hypothesis. No significant differences in throughfall rates were observed for individual trees; however, grouping the trees by size revealed significant differences in canopy throughfall. A 2^3 factorial analysis including rain depth, tree size, and average windspeed showed that rain depth x windspeed interaction followed by the combined interaction of all factors also revealed significant interactions. Hypothesis three studied throughfall at four different distances beneath a single oak (Quercus phellos) using tipping bucket rain gauges across 38 rain events totaling 27.8 inches. Paired T-tests showed highly significant differences in throughfall at each location. A 22 factorial analysis compared rain depth and wind direction, identifying significant rain depth differences. Lognormal linear regressions showed strong differences; throughfall was marginally lower near the tree trunk with increased throughfall observed nearing the edge of canopy, with interception decreasing at the edge of canopy due to the shade effect.

Grantor dc:publisher

University of Alabama Libraries

Year dc:date.issued

2022

Author dc:creator

• Bean, Ryan

Advisor dc:contributor.advisor

• Elliot, Mark

Contributors dc:contributor

• Pitt, Robert E.
• Terry, Leigh
• Williamson, Derek J.
• Clark, Shirley

• green infrastructure
• rainfall interception
• rainfall partitioning
• stormwater management

Statement dc:rights

• All rights reserved by the author unless otherwise indicated.

Language dc:language.iso

en_US, English

Dc Identifier Other

http://purl.lib.ua.edu/184350
u0015_0000001_0004399
Bean_alatus_0004D_14835

OAI identifier oai:identifier

oai:ir.ua.edu:123456789/8617