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University of New Mexico (2010)

Performance of a green roof lysimeter in an arid climate

Young, Rick

Titre : Performance of a green roof lysimeter in an arid climate

Auteur : Young, Rick

Université de soutenance : University of New Mexico

Grade : Master of Water Resources 2010

Résumé
Green roofs, also known as living roofs or eco-roofs, are becoming part of American architectural and engineering design as a method of reducing stormwater runoff. Although soil roofs have been in use for as long as adobe bricks, modern green roofs have a larger-scale function. Modern green roofs are used to solve or mitigate a number of architectural and engineering, stormwater management and ecological problems, especially in urban settings with large impervious areas. The effectiveness of green roofs in reducing these problems has been studied primarily in wet to moderately wet climates ; however, relatively little research has been performed in arid or semi-arid climates. This paper describes an evaluation of the hydrologic performance of green-roof technology in arid and semi-arid environments. The lysimeter was designed to stimulate the green roof on Pearl Hall at the University of New Mexico. The physical model was monitored for one year under climatic conditions typical of Albuquerque, New Mexico. The data collected included : volumetric soil moisture content over extended dry periods interspersed with monsoonal precipitation events ; a bulk analysis of the substrate, and a preliminary water balance for the soil. The results of this study suggest that eco-roofs in arid and semi-arid climates, with or without plantings, can aid in urban stormwater management. The Albuquerque climate is typical of other arid environments, consists of long periods of no rain followed by short but intense storms. During the monsoon season monitored in this study, two storms delivered over 25 millimeters of rain in less than twenty minutes. As a storm surge in an urban area this volume of water demands an extensive stormwater management system to manage it. The results of this study suggest that with a green roof in place, 96% of all precipitation falling on the roof will not be added to stormwater runoff. During the period of this study, only those two storms generated enough water that drainage occurred through the soil column and retained fifty-four and fifty-eight percent of the precipitation and delayed the surge by fifteen and thirty-five minutes respectively ; there was no breakthrough from any other storm event. The retention and delay of runoff is a principal goal of the current stormwater best management practices being encouraged by the U.S. Environmental Protection Agency.

Mots clés : Green roofs (Gardening)—Environmental aspects—New Mexico—Albuquerque. Urban runoff—New Mexico—Albuquerque—Management. Lysimeter.

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