Rainfall interception by olive trees in relation to leaf area

Interception of rainfall may be an important component of the water balance of rainfed olive orchards. To quantify the magnitude of interception by ol ive trees we conducted measurements during 1996 and 1997 in two orchards at Cordoba, Spain, on trees which differed in leaf areas. interception amount ed to about 8% of gross rainfall in an orchard that had an average leaf are a index (LAI) of 1.1. The measurements were then used to calibrate and vali date a model of interception which was subsequently used to compute average annual interception for a 7-year-period (1982-1989) at Cordoba. Three hypo thetical orchards were assumed, ranging in LAI values from 0.3 to 4.8; such extreme values represent traditional rainfed plantings and intensive irrig ated orchards, respectively. Relative interception varied from 7% at 0.3 LA I to 25% at 4.8 LAI of the average annual rainfall at Cordoba (606 mm). Int erception represents a significant component of the seasonal water balance of olive orchards, particularly in the case of intensive plantings where th e calculation of net irrigation requirements should include an estimate of interception loss. (C) 2001 Elsevier Science B,V. All lights reserved.