Dr Juan Quijano Baron

Levels and determinants of indoor carbon monoxide (CO) pollution were characterised in a pilot sample of households in Bogota, Colombia, in which natural gas appliances (NGA) were frequently used. Real-Time CO concentration measurements were conducted using Langan T15 electrochemical cells in kitchen and living rooms, at 73 homes. Results show that the use of NGA has a direct impact on indoor air quality with CO concentrations ranging between 5 and 150 parts-per-million. In 14 out of the 73 homes, CO concentrations were above the World Health Organization standards during at least 10% of the day. This is a matter of concern for local public health authority since the number of reported cases of CO involuntary intoxications in the city has significantly increased since 2008. Evidence presented hereby has important implications in regard to NGA installation standards and housing polices (especially in the case of low income dwelling). It urges to involve healthy-house concepts in building codes, to prevent inadequate indoor air quality and to improve people living conditions.

This paper presents the methodology for a 2D hydraulic modelling implemented for flood analysis in Bogotá, Colombia, where Torca River flows into the Bogotá River. A hydrological model was built in order to define the surface runoff from multiple tributaries areas in an ungauged basin; climate variability effects (ENSO) were taken into account to properly define flows that arrive at the Torca river reach that was modeled. Also backwater effects where considered by analyzing water level where the two rivers meet. The hydraulic simulation was performed using RiverFlow2D where the channel topology was defined by a topobathymetric survey and LIDAR images for river plains. Some recommendation for defining mesh characteristics are proposed after a sensibility analysis of its effects over water depths and velocities. Different return periods were evaluated according to joint exceedance probability combinations for two variables controlling the hydrological system (downstream water levels and surface runoff).

Models that represent the integrated urban drainage system are needed to holistically assess and manage its performance. Furthermore such models should ideally be spatially distributed to support evaluation of individual components and their role within the system. However, due to data constraints and computational costs, high resolution models of the sewer system are unlikely to be applicable when dealing with large scale and complex systems. This work assesses the value of a relatively simple semi-distributed grey-box modelling approach, which, in comparison with a fully distributed approach, decreases supporting data requirements but still aims to provide a reasonable spatial representation of the sewer system and its temporal variability, thus enabling integrated assessment. New methods for characterising uncertainty in flow and pollution load inputs during dry weather conditions are also used. A large urban catchment in Bogotá (Colombia) is used as a case study. Modelled and observed flow and pollutant concentration data demonstrated high apparently random variability of dry weather flow profiles within the sewer system. Against this variability, the effects of in-sewer processes were not identifiable except where backwaters caused particularly high retention times.