Estudio de la respuesta hidrológica de cubiertas verdes para la zona central de Chile.
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Date
2019
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Universidad de Concepción
Abstract
El crecimiento urbano conlleva consigo cambios morfológicos, topográficos y de recambio de superficies permeables por impermeables, esto conlleva una alteración de los procesos hidrológicos de infiltración, evapotranspiración y escorrentía en las cuencas urbanizadas, provocando un disminución de la recarga de agua subterránea, aumentando tanto las tasas de evapotranspiración como la escorrentía superficial en las ciudades, volviendo las cuencas urbanas más vulnerables a anegamientos y provocando problemas de contaminación de los cauces naturales. La presente investigación tiene tres objetivos de investigación. Primero, a través de una revisión bibliográfica de normas chilenas, leyes, instructivos técnicos y literatura científica, recomendar algunos tópicos de investigación que debieran ser promovidos en Chile en materia de drenaje urbano sustentable. Segundo, estudiar la influencia de las propiedades físicas de granulometría, conductividad eléctrica, retención de agua al igual que el contenido de nutrientes, sobre el estado fotosintético de una cobertura vegetal de sedum spurium vodoo para tres sustratos de cubierta verde comercializados en el país. Tercero, cuantificar el aporte real de las cubiertas verdes reteniendo y deteniendo la escorrentía para dos localidades de la zona central de Chile, a través de modelación hidrológica, con datos de alta resolución temporal, a partir de datos de escorrentía obtenidos experimentalmente mediante la construcción de siete módulos de cubierta verde y un simulador de precipitaciones. A raíz de los hallazgos encontrados en el estudio, se observa que Chile ha efectuado investigación científica en el área del drenaje urbano sustentable, pero la investigación se ha orientado principalmente a algunas medidas de control del agua en la fuente, los proyectos de construcción que incluyen los conceptos SUDS dentro de su planificación corresponden a algunos parque públicos y algunos condominios privados, se recomienda potenciar los tópicos de calidad del agua lluvia, implementación de medidas no estructurales y estudios de dispositivos SUDS tales como cubiertas verdes, pavimentos permeables, etc., que estén basados en modelación hidrológica e hidráulica, igualmente se recomiendan estudios para cuya finalidad permita rehabilitar los cauces urbanos. De las propiedades de los sustratos de cubierta verde que más impactaron en el estado general de la cobertura de sedum spurium vodoo fueron la retención de agua, sin embargo, se recomienda la garantía de un alto PH y la utilización de arcilla en el medio de crecimiento, se recomienda igualmente la utilización de medidores de clorofila portátiles. En cuanto al desempeño hidrológico, al separar las tormentas en eventos independientes con resolución de 1 minuto, se compararon los hidrogramas de los siete tratamientos de cubierta verde versus los hidrogramas de una cubierta de material impermeable y se obtuvieron reducciones de la escorrentía máxima entre 20-60%, la duración de la escorrentía fue de al menos tres horas más que la de una cubierta convencional, el centroide de escorrentía se retardó al menos 10 minutos, la retención resultó escasa debido a que se trabajó con cubiertas verdes de 10 cm de profundidad. Al estudiar estos estadísticos para las tormentas de diseño de duración.
Urban development carries with it morphological, topographic changes and a exchange of pervious surfaces for impervious surfaces, this carries a alteration of the hydrologic process of infiltration, evapotranspiration and surface runoff in the urbanized catchments, causing a disminution of groundwater recharge, increasing evapotranspiration rates as well as the peak surface runoff in the cities, all this causes more vulnerability to flooding and causing water pollution. The present research has three objectives, first, through a bibliographic review of technical documents, laws and scientific literature, estabish research topics that should be promoted in Chile in the SUDS field. Second, to study the influence of physical properties as grain size, electric conductivity, water retention as well as the nutrient content on the photosinthetic state of a vegetal cover of sedum spurium vodoo for three comercial green roof substrates in Chile. Third, quantify the real impact of green roof retention and detention of urban runoff for two cities located in central Chile, through hydrologic modelling, with highly temporal resolution data, through runoff data collected experimentally from seven green roof modules and a rainfall simulator. the findings of this study are that there is evidence of scientific research in the SUDS field, but this research has been oriented to some source control measures, the proyects who consider the SUDS concepts inside the planning are a few public places and some private neighborhoods, it is recomeded to develop research in the topics of stormwater quality, the implementation of non-structural measures and SUDS devices like green roofs, pervious pavements, etc., wich are based on hydrological or hydraulic modelling, aditionally, to advance in urban stream rehabilitation. The most influencer substrate propertie on the general state of the sedum spurium vodoo was water retention, however, it is recommended to mantain a high PH and a clay percent in the green roof substrate, also, the portatil chlorophyl measurement device proved to be a usefull in this kind of studies. About the hydrologic behaviour of the green roof, the storms was separated into individual events of 1 minute resolution, and the impervious hydrograph was compared with seven green roof hydrographs and it was obtain 20-60% peak runoff attenuation, the aditional green roof runoff duration was at least three hours more than a impervious roof, the runoff centroid delay was at least 10 minutes, but retention was low because extensive roofs of 10 cm depth were used in this study. The same parameters were obtained considering design hyetographs with diferent return periods and sub-daily time resolutions in this case, the peak runoff attenuation obtained was 30-80% for return periods between 2-60 years, the aditional green roof runoff duration was 2-7 hours more than a impervious roof, the runoff centroid delay was 5-10 minutes, the retention, like before, was low because of the same reason exposed above. The findings of this research contribute to provide experimental based criteria wich may be usefull to develop new green roof substrates based on the photosinthetic performance of the vegetal especie, also, the results from green roof peak runoff attenuation, the aditional runoff duration, and the runoff centroid delay, considering both the storm event separation and the design hyetographs contribute to promote the green roof construction in central Chile and in Chile itself.
Urban development carries with it morphological, topographic changes and a exchange of pervious surfaces for impervious surfaces, this carries a alteration of the hydrologic process of infiltration, evapotranspiration and surface runoff in the urbanized catchments, causing a disminution of groundwater recharge, increasing evapotranspiration rates as well as the peak surface runoff in the cities, all this causes more vulnerability to flooding and causing water pollution. The present research has three objectives, first, through a bibliographic review of technical documents, laws and scientific literature, estabish research topics that should be promoted in Chile in the SUDS field. Second, to study the influence of physical properties as grain size, electric conductivity, water retention as well as the nutrient content on the photosinthetic state of a vegetal cover of sedum spurium vodoo for three comercial green roof substrates in Chile. Third, quantify the real impact of green roof retention and detention of urban runoff for two cities located in central Chile, through hydrologic modelling, with highly temporal resolution data, through runoff data collected experimentally from seven green roof modules and a rainfall simulator. the findings of this study are that there is evidence of scientific research in the SUDS field, but this research has been oriented to some source control measures, the proyects who consider the SUDS concepts inside the planning are a few public places and some private neighborhoods, it is recomeded to develop research in the topics of stormwater quality, the implementation of non-structural measures and SUDS devices like green roofs, pervious pavements, etc., wich are based on hydrological or hydraulic modelling, aditionally, to advance in urban stream rehabilitation. The most influencer substrate propertie on the general state of the sedum spurium vodoo was water retention, however, it is recommended to mantain a high PH and a clay percent in the green roof substrate, also, the portatil chlorophyl measurement device proved to be a usefull in this kind of studies. About the hydrologic behaviour of the green roof, the storms was separated into individual events of 1 minute resolution, and the impervious hydrograph was compared with seven green roof hydrographs and it was obtain 20-60% peak runoff attenuation, the aditional green roof runoff duration was at least three hours more than a impervious roof, the runoff centroid delay was at least 10 minutes, but retention was low because extensive roofs of 10 cm depth were used in this study. The same parameters were obtained considering design hyetographs with diferent return periods and sub-daily time resolutions in this case, the peak runoff attenuation obtained was 30-80% for return periods between 2-60 years, the aditional green roof runoff duration was 2-7 hours more than a impervious roof, the runoff centroid delay was 5-10 minutes, the retention, like before, was low because of the same reason exposed above. The findings of this research contribute to provide experimental based criteria wich may be usefull to develop new green roof substrates based on the photosinthetic performance of the vegetal especie, also, the results from green roof peak runoff attenuation, the aditional runoff duration, and the runoff centroid delay, considering both the storm event separation and the design hyetographs contribute to promote the green roof construction in central Chile and in Chile itself.
Description
Tesis presentada para optar al grado de Doctor en Ingeniería Agrícola con mención en Recursos Hídricos en la Agricultura
Keywords
Aguas Lluvias (Abastecimiento de Agua), Cuencas hidrográficas, Evapotranspiración, Agua limpia y saneamiento