Extensive green roof is one of the sustainable urban stormwater management alternatives to manage and mitigate the urban surface runoff. In order to implement green roofs more effectively, suitable plant species and substrate components for tropical climate must be identified. The aim of this study is to investigate the evapotranspiration (ET) behaviors in extensive green roofs based on different substrate types and local native plant species. Four green roof test beds containing pro-mixing pot and burn soils were each vegetated with Axonopus Compressus (grass) and Portulaca Grandiflora (sedum). A weather station with soil moisture sensors was installed to measure the weather and soil moisture data. The results showed that the mean ET rates for grass-pot soil, sedum-pot soil, grass-burn soil and sedum-burn soil were 1.32 ± 0.41 mm/day, 2.31 ± 0.72 mm/day, 1.47 ± 0.39 mm/day and 2.31 ± 0.43 mm/day, respectively. It is noted that environmental parameters such as ambient temperature, solar radiation and wind speed showed significantly positive relationship (p value < 0.01) with ET rates of green roofs except relative humidity. The crop coefficients (K_s) for the studied green roof plant species are estimated based on actual and reference evapotranspiration rates. The sedum planted in burn soil showed the highest crop coefficient (0.64), followed by sedum in pot soil (0.62), grass in burn soil (0.39) and grass in pot soils (0.37), respectively. The findings in this study also showed that substrate with better water retention capacity generally improved the K_s values.

中文翻译：

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热带屋顶绿化本土植物蒸散量测量与作物系数估算

广泛的绿色屋顶是管理和缓解城市地表径流的可持续城市雨水管理替代方案之一。为了更有效地实施绿色屋顶，必须确定适合热带气候的植物种类和基质成分。本研究的目的是研究基于不同基质类型和当地本地植物物种的大面积绿色屋顶的蒸散 (ET) 行为。四个包含预拌盆和燃烧土壤的绿色屋顶试验床，每个试验台都种植有Axonopus Compressus（草）和Portulaca Grandiflora（景天）。安装了一个带有土壤湿度传感器的气象站来测量天气和土壤湿度数据。结果表明，草盆土、景天盆土、草烧土和景天烧土的平均ET率分别为1.32±0.41 mm/天、2.31±0.72 mm/天、1.47±0.39 mm/天和分别为 2.31 ± 0.43 毫米/天。值得注意的是，环境温度、太阳辐射和风速等环境参数与绿色屋顶除相对湿度外的ET率呈显着正相关（p值<0.01）。作物系数（K _s) 所研究的屋顶绿化植物物种是根据实际和参考蒸散率估算的。种植在烧土中的景天表现出最高的作物系数（0.64），其次是盆土中的景天（0.62）、烧土中的草（0.39）和盆土中的草（0.37）。本研究的结果还表明，具有更好保水能力的底物通常会提高 K _s值。