Influence of Stemflow Measurement on Interception Estimation Under Eucalyptus Plantations

Abstract

Eucalyptus is a widely planted tree species, which covers approximately 20 million hectare of land area across the world. The accurate estimate of interception under eucalyptus is vital for efficient water balance and hydrological model. The throughfall (TF) and stemflow were measured in-situ for 106 nos. rainfall events varying between 2.8 mm to 59.6 mm, during the monsoon of year 2017–18. The measured TF lies in the range of 50 to 80% with an average of 66.9%, whereas the measured SF lies in the ranged from 2.4 to 12.4% with an average of 7.6%. The estimation of interception loss was achieved through two different approaches. In the first scheme, the estimation is based on in-situ measurement of TF and SF and is expressed in terms of Im. However, in the second scheme, it is based on in-situ measurement of TF but a fixed value of SF (i.e., I5, I7.5 and I10 for 5, 7.5 and 10% of incident rainfall respectively). The estimated Im lies in the range of 10.3 to 38.9% with an average of 25.5%. Similarly, the average I5, I7.5, and I10 estimated was 28.1, 25.6, and 32.1%, respectively. Single factor ANOVA test showed a significant variation of I5 and I10 with Im, which emphasis on need of judiciously selection of SF percentage in absence of measured SF data. Further, the observed variation was insignificant between Im and I7.5. The SF fixed as 7.5% of incident rainfall is closest to the average measured SF (7.6% of incident rainfall), thus it may only applicable for measured rainfall range 2.8 mm to 59.6 mm. This study indicates plantation specific SF percentage is important to obtain better interception estimation for water balance and hydrological studies of larger planted areas.