Sérgio Koide

Does parameterization influence the performance of slope stability model results? A case study in Rio de Janeiro, Brazil

We produce factor of safety (FOS) and slope failure susceptibility index (SFSI) maps for a 4.4-km2 study area in Rio de Janeiro, Brazil, in order to explore the sensitivity of the geotechnical and geohydraulic parameterization on the model outcomes. Thereby, we consider parameter spaces instead of combinations of discrete values. SFSI is defined as the fraction of tested parameter combinations within a given space yielding FOS <1. We repeat our physically based calculations for various parameter spaces, employing the infinite slope stability model and the sliding surface model of the software r.slope.stability for testing the geotechnical parameters and the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model (TRIGRS) for testing the geohydraulic parameters. Whilst the results vary considerably in terms of their conservativeness, the ability to reproduce the spatial patterns of the observed landslide release areas is relatively insensitive to the variation of the parameterization as long as there is sufficient pattern in the results. We conclude that landslide susceptibility maps yielded by catchment-scale physically based models should not be interpreted in absolute terms and suggest that efforts to develop better strategies for dealing with the uncertainties in the spatial variation of the key parameters should be given priority in future slope stability modelling efforts.

Human risk assessment of benzene after a gasoline station fuel leak

OBJECTIVE To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater fl ow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 μg/L) since December 2001, fi ve months before they reported the leak. The mean benzene level in drinking water (72.2 μg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 μg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 μg/kg bw/ day (5 x 10 -7 cancer risk per 10 6 individuals). The level of benzene in water vapor while showering reached 7.5 μg/m 3 for children (1 per 10 4 cancer risk). Total cancer risk ranged from 110 to 200 per 10 6 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment. DESCRIPTORS: Benzene, toxicity. Gasoline, adverse effects. Chemical Hazard Release. Chemical Accidents. Environmental Exposure. Water Pollution. Risk Assessment.

Urban Stormwater Monitoring and Modelling at the Riacho Fundo Sub-basin, Brasília – DF

This research is aimed to evaluate the application of the PCSWMM model to an urban watershed in Paranoa Lake basin to verify if the hydraulic model correctly simulates the flow discharge, an important step to estimate the loads conveyed to the Lake. This study was carried out to evaluate the use of the SWMM model on small urban basins in central Brazil, based on rainfall and runoff monitoring during events. The modelling was carried out using observed rainfall as input to PCSWMM model with SCS method generation. It was confirmed that this model fits well to this type of watershed, however it can be improved by calibration to single events.

Hydrological Modelling and Detention Ponds Evaluation at Paranoa Lake - Brazil

Paranoa Lake is an urban lake and since last year Brasilia started to use its waters for human consumption. Until the 1990’s algae and cyanobacteria blooms occurred and improvements on wastewater treatment plants brought the water quality to very good conditions in the 2000’s. Recently water quality is starting to deteriorate mainly due to diffuse pollution. Thus, the evaluation of urban drainage waters entering the lake and the proposition of technological alternatives to minimize impacts are important for the analysis of diffuse urban pollution flowing into the lake. Quantitative and qualitative behaviour of the urban drainage waters were analysed by means of monitoring the precipitation amount and runoff flow and quality. Mathematical modelling using the SWMM and PCSWMM programs was carried out, and good results were obtained for flow modelling. However, in water quality simulations, poorer response was obtained. It was also evaluated the implementation of 13 alternatives of detention ponds to study the effects of their location on the removal of pollutants, as well as influences on the network flow support. It was observed that ponds allocated in the downstream part of the network are more efficient, but requireconstruction in environmentally and urbanistically problematic areas and high commercial value. Alternatives with smaller volumes in areas areas near the center ofthe basin can meet flood-damping needs of the presently constructed drainage network.

Modelling Runoff in Watershed Without Calibration Using PCSWMM

Urbanization process changes the runoff generation, essential factor for drainage systems design. Unfortunately, it is very common in Brazil and in underdeveloped countries the lack of rainfall and field data, being frequently adopted the rational method for runoff estimation. To improve runoff estimation, it is growing the use of hydrodynamics models performed with computer programs, such as PCSWMM™ (SWMM with GIS integrated), but, most of the times model parameter values have to be assumed based on default values or developers´ recommendations. In this study, PCSWMM was used for calculation of drainage system of Riacho Fundo’s urban area in Federal District in Brazil, in preparation for future analysis of LID implementation. The main objective is to analyze the PCSWMM use in a watershed without data for calibration using the SCS method, implementing PCSWMM recommendations and comparing them with the rational method in terms of peak flow results. The results showed that adopting PCSWMM recommendation only for the Imperv (%) parameter for subcatchments characteristics is the simulated scenario which is closest to rational method, while other modifications from the default values alter substantially the peak flow value.

Evaluacion de riesgo humano al benceno posterior al derrame de combustible en gasolinera

OBJECTIVE To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater fl ow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 μg/L) since December 2001, fi ve months before they reported the leak. The mean benzene level in drinking water (72.2 μg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 μg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 μg/kg bw/ day (5 x 10 -7 cancer risk per 10 6 individuals). The level of benzene in water vapor while showering reached 7.5 μg/m 3 for children (1 per 10 4 cancer risk). Total cancer risk ranged from 110 to 200 per 10 6 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment. DESCRIPTORS: Benzene, toxicity. Gasoline, adverse effects. Chemical Hazard Release. Chemical Accidents. Environmental Exposure. Water Pollution. Risk Assessment.

Avaliacao de risco humano a benzeno apos vazamento de combustivel em posto de gasolina

OBJECTIVE To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater fl ow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 μg/L) since December 2001, fi ve months before they reported the leak. The mean benzene level in drinking water (72.2 μg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 μg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 μg/kg bw/ day (5 x 10 -7 cancer risk per 10 6 individuals). The level of benzene in water vapor while showering reached 7.5 μg/m 3 for children (1 per 10 4 cancer risk). Total cancer risk ranged from 110 to 200 per 10 6 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment. DESCRIPTORS: Benzene, toxicity. Gasoline, adverse effects. Chemical Hazard Release. Chemical Accidents. Environmental Exposure. Water Pollution. Risk Assessment.