Determination of the volume of stormwater capture for bioretención systems in concepcion (Chile).

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Jose Vargas, Carlos Padilla, Alex Schwarz

Thursday 2 july 2015

17:42 - 17:45h at Central America (level 0)

Themes: (T) Water resources and hydro informatics (WRHI), (ST) Catchment hydrology, Poster pitches

Parallel session: Poster pitches: 13H. WRHI - Catchment

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Among the alternative techniques of urban drainage, the system of bio-retention stands up. This system consist of a small vegetated basin compuse of horizontal layers, with specific functions and that has for objective give treatment to the urban run-off generated by rain water, before his unload to a receptor body , by a serie of chemical and biochemical processes. In this proyect it is sought to determine a capture volume of biofilter, that corresponds to the storage limited of the depth of detention and his infiltration area. From the analysis of the pluviographics records of the Carriel Sur station in Concepción (Chile) between 1989 and 2010, with the assist of the WQ-COSM statistical software, developed by the Urban Watershelds Research Institute (UWRI) on Denver, US. This software, across the continue simulation, using the Rational method and a mass balance, determine the volume of capture necesarry to dimension the system. For the calculation of the volume of capture was adopted a focusing that considerer the currently rain's event blameworthy of washing the surface of drainage and to provoke the major impact on the quality of the body receptor's water. For the calculation of the volume of capture, the WQ-COSM model requiered parameters like the runoff coefficient; the time of emptying, that will determine the rate of the treated water that's going to exit of the biofilter; the time of the separation of events, equal of the dry period between rain events necesaries to assume the independence among them; and the surface storage, that also include the losses because of a interception and infiltration during a storm, amount that establish if a precipitation event generates surface run-off. The last two mentioned parameters are essential for the power of turn a criterion of determination too wide and just a little studied. Because of that, was made an analysis of sensitivity that concluded that the volume of capture of the biofilter it's too sensitive to these parameters, so it's recommended to estimate specific amounts for every basin.