| Popis: |
Stormwater mitigation and pollutant transport within living roof systems is largely influenced by the hydrological performance of their media layers. Unsaturated 1D hydrological process in 10-cm depth cores of four living roof media under 30-min steady simulated rainfalls of 2- and 100-yr recurrence interval were measured. The composition of the media involved two gradations of pumice aggregate (fine and coarse) and three volumetric ratio of compost (0, 10 and 20%). Stable wetting fronts existed in all the tested media. During the 2-yr 30-min storm, the medium with 100% fine grade pumice delays the runoff longer than the medium with 100% coarse grade pumice. The compost-amended coarse pumice delays the runoff peak discharge more compared to the 100% coarse pumice. The difference in retention due to the pumice aggregate type and compost amendment is small for both storm events. The application of the Richards equation with different characterizations of medium hydraulic properties was also explored in HYDRUS1D. The results suggest that for media with steady wetting fronts, the Richards equation is applicable when medium hydraulic properties are characterized by a dualporosity model proposed by Durner (1994). Modeling the medium porosity as two different, overlapping pore regions produce more accurate hydrograph simulation than a single homogeneous pore system, when compared against measured flows. |
