Efficiency of intensive green roof in high intensity rainfall for stormwater treatment: selection of vegetations

摘要

Receiving an average 3000mm of rainfall depth with high intensity, Malaysia is known as a tropical climate country. Currently, Malaysia proactively promotes the use of Sustainable Urban Drainage Syatem (SUDS) as indicated in the Malaysian's Stormwater Management Manual namely the Urban Stormwater Management Manual of Malaysia (MSMA) 1st and 2nd version. The manual is promoting the implementation of SUDS facilities whether as a single facility or integrated ones which is a combination of two or more SUDS facilities. However green roof is not included in this manual. Thus the objectives of this paper are to share the preliminary study of intensive green roof tested under high intensity rainfall (159mm/hr) using rainfall simulator and four intensive green roof test bed with different vegetations. Three species selected for each test bed namely Kalanchoe pinnata (K.pinnata), Axonopus compressus (A.compressus) and Arachis pintoi (A.pintoi). Another test bed is to leave in a baren condition without vegetation as a control unit. Media or substrate use for these test beds are similar which consists of drainage cells, geotextile, river sand and top soils. Parameters studied are potassium (K), Total Phosphate (TP), Total Nitrogen (TN) and Ammoniacal Nitrogen (AN). Results show that K.pinnata performed well in the reduction of TP (37.50% - 89%) and AN (68.90% - 95.34%) followed by A.pintoi (TP: 36.68% - 82.50%, AN: 59.92% - 92.68%) and A.compressus (TP: 20.11% - 80.15%, AN: 89.52% - 93.44%). Another studied parameters (K and TN) show leaching in outflow of test bed. It is believed due to the fertilizer used for plant growth. In term of quantity control, all test beds showed reduction percentage of runoff hydrograph in the range of 9% to 67.