Water
2018
green roof; semiarid climate; hydrological model; validation; substrate moisture; irrigation need; runoff coefficient
Green roofs offer a series of benefits to buildings and to the urban environment. Their use in dry climates requires optimizing the choice of their components (i.e., vegetation, substrate and drainage layer) for the specific local climatic conditions, in order to minimize irrigations needs while preserving the attributes of the roof. In this study, we calibrated and validated an existing hydrological model—IHMORS—for the simulation of the hydrological performance of green roofs. Simulated results were compared to experimental data obtained in an outdoor test facility on several green roof specimens, representing a variety of green roofs configurations. IHMORS was able to reasonably predict the soil moisture dynamics for all tested specimens. The specimens of 10 cm depth were the best simulated by the model, while some overestimation was observed during the model validation for the 5 and 20 cm depth specimens. The model was then used to estimate the number of days in which irrigation is needed, as well as analyze the water runoff control performance of all specimens. We related the amount of water retained by the substrate and depth, magnitude and intensity of precipitation event, and the initial substrate moisture. For all events, the lowest runoff coefficient was simulated for the 20 cm specimens. Our study showed the full potential of the model for estimating the water needs and the runoff control performances of different variants of green roofs.
Josefina Herrera 1; Gilles Flamant 2; Jorge Gironás 1,3,4,5,*; Sergio Vera 2,3, Carlos A. Bonilla 1,3; Waldo Bustamante 3,6; and Francisco Suárez 1,3,7
1 Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; jlherrer@uc.cl (J.H.); cbonilla@ing.puc.cl (C.A.B.); fsuarez@ing.puc.cl (F.S.)
2 Departamento de Ingeniería y Gestión de la Construcción, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; gillesflamant@hotmail.com (G.F.); svera@ing.puc.cl (S.V.)
3 Centro de Desarrollo Urbano Sustentable CONICYT/FONDAP/15110020, Santiago 7520245, Chile; wbustamante@uc.cl
4 Centro Interdisciplinario de Cambio Global, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
5 Centro de Investigación para la Gestión Integrada de Desastres Naturales CONICYT/FONDAP/15110017, Santiago 7820436, Chile
6 Escuela de Arquitectura, Pontificia Universidad Católica de Chile, Santiago 7520245, Chile
7 Centro de Excelencia en Geotermia de los Andes CONICYT/FONDAP/15090013, Santiago 8370450, Chile
* Correspondence: jgironas@ing.puc.cl; Tel.: +56-2-23544227