Alexandria Engineering Journal (Feb 2021)
Water absorption features of organic ground cover under artificial rainfall
Abstract
Capable of retaining rainwater, Organic Ground Cover (OGC) is an ecological material for urban greening. The water absorption features of various OGC materials should be identified before selecting the proper OGC for places under different climates. With the aid of a rainfall simulator, this paper experimentally explores the water absorption features of 16 common OGC materials at the rainfall intensity of 48 mm/h. Based on the experimental results, the change trends of multiple indices were analyzed for these materials, namely, volumetric water absorption ratio, volumetric water absorption rate, mass water absorption ratio, mass water absorption rate, pre-drainage duration, and near saturation duration. The results show that the OGC materials differed significantly in water absorption capacity: (1) SD and PPB2 had the best volumetric water absorption ratios, while EC had the worst volumetric water absorption ratio. (2) The volumetric water absorption rates of all materials reached the maximum in 0–10 min after the artificial rainfall, and then decreased rapidly; At 10 min, the proportion of volumetric water absorption ratios of the 16 materials averaged at 74%; The highest (94%) and lowest (36%) proportions belong to OC and SD, respectively. (3) OC had the best mass water absorption ratio, while EC had the worst mass water absorption ratio. (4) At 10 min, the proportion of mass water absorption ratio of each material was the same as that of volumetric water absorption ratio; OC, PN, CF, CFP, PPB1, WB, and ANBM had obviously higher mass water absorption rates than other materials, while PS, FPB2 and EC had relatively small mass water absorption rates. (5) The shortest and longest pre-drainage durations belong to OC (2 min) and SD (13.67 min), respectively. (6) The shortest pre-near saturation belongs to CFP, PPB1, FPB2 and EC (13.33 min), the longest pre-near saturation belongs to SD (50 min), respectively. The research results provide a reference for the selection of the OGC materials in urban greening.
