Browsing by Author "Gironas, Jorge"

Now showing 1 - 8 of 8
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    A morpho-climatic instantaneous unit hydrograph model for urban catchments based on the kinematic wave approximation
    (ELSEVIER SCIENCE BV, 2009) Gironas, Jorge; Niemann, Jeffrey D.; Roesner, Larry A.; Rodriguez, Fabrice; Andrieu, Herve
    Stormwater models are valuable tools in urban planning as well as stormwater system design and management. Although the hydraulic simulation of pipes and channels in these models is often quite sophisticated, the hydrologic simulation of the flow contributing to the hydraulic elements is frequently greatly simplified. Hydrologic simulation of urban catchments is made particularly complex due to the presence of features such as streets, small pipes, and channels. In this study, we develop a new model called the U-McIUH (Urban Morpho-climatic Instantaneous Unit Hydrograph), which defines the IUH as the probability density function of the travel time from a random location in the urban terrain to the outlet. Flow paths are extracted from a specially processed digital elevation model that incorporates hillslopes, streets, pipes, and channels, and travel times are computed in each cell using the average wave celerity from kinematic wave theory. These expressions depend on the upstream contribution of flow and the excess rainfall intensity, so they incorporate the so-called climatic dependence of the IUH, which is the dependence of the unit hydrograph on the rainfall intensity. Rainfall pulses of different intensities are convoluted with their respective IUH and superimposed to generate the response to a given storm event. The application of the model to a real catchment provides good reproduction of observed hydrographs, suggesting that the U-McIUH is able to capture some significant hydrologic properties of the catchment. The model is studied by analyzing the effects of (1) the upstream contribution of flow on the travel time formulation, (2) the variation of flow velocities within the urban catchment, (3) the non-linear dependence of the IUH on the rainfall intensity (i.e. the climatic dependence), and (4) the spatial distribution of imperviousness. Overall, these results suggest that the presence of artificial elements in urban watersheds has a significant role in determining the travel times and thus the hydrologic response of the watershed. (C) 2009 Elsevier B.V. All rights reserved.
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    Evaluation of Methods for Representing Urban Terrain in Storm-Water Modeling
    (ASCE-AMER SOC CIVIL ENGINEERS, 2010) Gironas, Jorge; Niemann, Jeffrey D.; Roesner, Larry A.; Rodriguez, Fabrice; Andrieu, Herve
    Many storm-water modeling problems consider watersheds comprised of complex flow networks including surfaces, streets, pipes, and channels. Ideally, hydrologic methods would be used to model the accumulation of runoff on surfaces while hydraulic methods would be used to explicitly model the flow in each street, pipe, and channel. In many practical circumstances, only the largest pipes and channels are explicitly modeled with hydraulic methods. Thus, most subcatchments include numerous streets and small pipes that can affect the accumulation and movement of flow. Digital elevation models (DEMs) are widely used to determine geometric characteristics of these subcatchments, but street gutters and pipes are not resolved in such data. To overcome this problem, known streets and pipes are often "burned" into the surface by reducing the local elevations by a specified amount before calculating flow paths and the associated subcatchment characteristics. In this paper, existing and proposed methods for including these conduits into DEM surfaces are evaluated. The results suggest that the derived characteristics are sensitive to the selected method. We also find that a new method, which makes use of known pipe elevations, is most successful at reproducing realistic flow paths. Finally, we find that errors in the implied watershed characteristics are difficult to overcome by calibration of other model parameters.
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    Experimental Analysis and Modeling of a Stormwater Perlite Filter
    (WATER ENVIRONMENT FEDERATION, 2008) Gironas, Jorge; Adriasola, Jose M.; Fernandez, Bonifacio
    This paper presents the study of a mixed porous media composed of expanded perlite and a nonwoven needle-punched geotextile used to reduce the suspended solids load and concentration in urban runoff. Laboratory procedures were designed to quantify the suspended solids removal efficiency and variation in time of filtration rate. Different grain-size distributions of expanded perlite, diverse suspended solids concentrations, and different hydraulic and geometric conditions were tested to determine the most effective filter media. A dimensionless parameter, termed Global Performance Index (GPI), was developed to reach this objective. Measured data were also used to build a dimensional and a regression model to represent the performance of the filter media mathematically. The theory, derivation, and performance of both models are presented and compared with an existent empirical model. The dimensional model better reproduces the observations, becoming a useful tool for the design, operation, and evaluation of commercial porous media filters. Water Environ. Res., 80, 524 (2008).
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    Forecasting flood hazards in real time: a surrogate model for hydrometeorological events in an Andean watershed
    (2020) Teresa Contreras, Maria; Gironas, Jorge; Escauriaza Mesa, Cristian Rodrigo; CEDEUS (Chile)
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    From mathematical models to policy design: Predicting greywater reuse scheme effectiveness and water reclamation benefits based on individuals’ preferences
    (2021) Amaris, Gloria; Dawson, Richard; Gironas, Jorge; Hess, Stephane; Ortuzar Salas, Juan De Dios; CEDEUS (Chile)
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    From Multi-Risk Evaluation to Resilience Planning: The Case of Central Chilean Coastal Cities
    (2019) Barria, Pilar; Luisa Cruzat, Maria; Cienfuegos, Rodrigo; Gironas, Jorge; Escauriaza Mesa, Cristian Rodrigo; Bonilla, Carlos; Moris, Roberto; Ledezma, Christian; Guerra, Maricarmen; Rodriguez, Raimundo; Torres, Alma
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    Integrated Water Resource Management and Energy Requirements for Water Supply in the Copiapo River Basin, Chile
    (MDPI, 2014) Suarez, Francisco; Munoz, Jose F.; Fernandez, Bonifacio; Dorsaz, Jean Marc; Hunter, Christian K.; Karavitis, Christos A.; Gironas, Jorge; CEDEUS (Chile)
    Population and industry growth in dry climates are fully tied to significant increase in water and energy demands. Because water affects many economic, social and environmental aspects, an interdisciplinary approach is needed to solve current and future water scarcity problems, and to minimize energy requirements in water production. Such a task requires integrated water modeling tools able to couple surface water and groundwater, which allow for managing complex basins where multiple stakeholders and water users face an intense competition for limited freshwater resources. This work develops an integrated water resource management model to investigate the water-energy nexus in reducing water stress in the Copiapo River basin, an arid, highly vulnerable basin in northern Chile. The model was utilized to characterize groundwater and surface water resources, and water demand and uses. Different management scenarios were evaluated to estimate future resource availability, and compared in terms of energy requirements and costs for desalinating seawater to eliminate the corresponding water deficit. Results show a basin facing a very complex future unless measures are adopted. When a 30% uniform reduction of water consumption is achieved, 70 GWh over the next 30 years are required to provide the energy needed to increase the available water through seawater desalination. In arid basins, this energy could be supplied by solar energy, thus addressing water shortage problems through integrated water resource management combined with new technologies of water production driven by renewable energy sources.
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    Modeling changes to the hydrodynamic characteristics of agglomerated copper tailings
    (ELSEVIER, 2011) Fernanda Hernandez Lopez, Maria; Ortiz, Cristian; Bonilla, Carlos A.; Gironas, Jorge; Francisco Munoz, Jose
    This paper describes the effect of acid leaching on the hydrodynamic properties of agglomerated copper tailings. Both the suction and the hydraulic conductivity curves were obtained before and after acid application in laboratory columns under unsaturated flow conditions. Using a classical approach originally developed for water and soil, we determined whether the post-acid application characteristic curves could be obtained from the pre-acid application ones. Results showed that acid modified the hydrodynamic properties of agglomerated tailings. Both the macropore volume and the saturated hydraulic conductivity decreased. For the same water content, the unsaturated hydraulic conductivity decreased and the suction head increased. The pre-acid application characteristic curves can be used to estimate the corresponding post-acid application curves. (C) 2011 Elsevier B.V. All rights reserved.