ARI REVIEW FOR 2016-2017

ETo) and (iii) to model the grey area and storage tank size required for a zero-water green roof system. A rooftop experiment was carried out in Nicosia, Cyprus between February 2016 and April 2017, with 16 test beds equipped with drainage and surface runoff tanks, soil moisture sensors and a meteorological station. The two substrate mixtures consisted of perlite: pumice (5-8 mm): pumice (0-8 mm): zeolite: soil: compost, with a volumetric ratio of 0:30:25:15:15:15 (Mix1) and 12:13:27:22:13:13 (Mix2). Mix1 had a depth of 15.5 cm and a dry weight of 121 kg/m 2 , Mix2 had a depth of 17.5 cm and a dry weight of 124 kg/m 2 . The substrate mixture and plant species had no significant effect on the total stormwater retention for the 15-month study period. Average stormwater retention of the 16 test beds was 77% of the 371-mm rainfall. Only 9 of the 19 drainage events exhibited surface runoff, with a total of 0.5 mm over the study period. A survival rate of 38% and 88% was recorded for Euphorbia veneris for the 15% and 30% (ET o ) treatments, respectively. Frankenia laevis was affected by stress at the beginning of the irrigation period and only the 30% ET o treatment was applied, for which a 20% survival rate was observed. A 30-year meteorological record (average rain 315 mm/year, reference evapotranspiration 1515 mm/year) was used in a daily water balance model. Results show that a 100-m 2 roof under 30% ET o irrigation with collected stormwater, and up to 100% ET o when water is available, would require a 54.5 m 3 tank and 55% of the roof to be grey. Further research could examine a variety of local drought-tolerant species, individually and mixed, under 30 to 50% ET o irrigation treatments. ( K. Charalambous, A. Bruggeman, L. Vassiliou, M. Eliades, C. Camera ) 61 Natural Resources and Environment Table 1. Plant performance during the deficit irrigation period (June to October) 2016, for the combinations 15% ET o - E .veneris (Irr15%-EU), 30% ET o - E .veneris (Irr30%-EU) and 30% ET o - F .laevis (Irr30%-FR) 1 4 repetitions- 24 plants/1.2 m 2 2 4 repetitions- 24 plants/1.2 m 2 3 8 repetitions- 96 plants/2.4 m 2