Simulation of Infrastructure Options for Urban Water Management in Two Urban Catchments in Bogotá, Colombia

Carlos Peña-Guzmán, Joaquín Melgarejo, Inmaculada Lopez-Ortiz, Duvan Mesa
2017 Water  
Urban areas are currently experiencing rapid growth, which brings with it increases in the population, the expansion of impervious surfaces, and an overall jump in the environmental and hydrological impact. To mitigate such an impact, different strategies proposed to tackle this problem often vary; for example, stormwater tanks, the reuse of wastewater and grey water, the installation of equipment to reduce water consumption, and education-based approaches. Consequently, this article presents
more » ... article presents the simulation and evaluation of implementing infrastructure options (stormwater harvesting, reuse of industrial waters, water-saving technology in residential sectors, and reuse of water from washing machines) for managing urban water in two urban catchments (Fucha and Tunjuelo) in Bogotá, Colombia, over three periods: baseline, 10 years, and 20 years. The simulation was performed using the software Urban Volume Quality (UVQ) and revealed a possible reduction in drinking water consumption of up to 47% for the Fucha Catchment and 40% for the Tunjuelo Catchment; with respect to wastewater, the reduction was up to 20% for the Fucha Catchment and 25% for the Tunjuelo Catchment. Lastly, two scenarios were evaluated in terms of potential savings related to water supply and sewage fees. The implementation of strategies 3 and 6 insofar as these two strategies impacted the hydric resources. Therefore, there would be a significant reduction in contaminant loads and notable economic benefits attributable to implementing these strategies. Several strategies for urban water management have been proposed, including structural and nonstructural actions. These actions have been applied to different scales, from regions, cities, towns, and neighborhoods to houses, apartments, and independent properties, all of which contribute-to varying degrees-to the IUWM [12] . Some examples include: (i) harvesting stormwater; (ii) reusing greywater and wastewater; (iii) treating stormwater, wastewater, and greywater; (iv) runoff and contaminant reduction in stormwater via structural work (filters, artificial wetlands, porous pavement, etc.); (v) water-saving technology; and (vi) environmental education, among other proposals [13] [14] [15] [16] [17] [18] [19] [20] . To evaluate the implementation or the selection of these options, software and mathematical models have been used, offering appropriate technical support to plan cities' growth and sustainability. Among the most frequently employed infrastructure options for smaller-scale alternatives are the use of rainwater, reuse of greywater, and water-saving devices. The collection of rainwater is a clear and direct strategy for the sustainability of the urban water cycle. It offers myriad benefits, including: reduced water demand (30-70%), less hydric stress, minimized contaminant loads, and flooding mitigation [21] [22] [23] [24] [25] . The use of greywater offers notable potential in light of the constant supply of this source, i.e., a high population density in cities leads to large volumes of greywater [26] . Water-saving devices, for their part, have been gaining traction due to their ease of implementation and affordability. These strategies have been studied across the globe with promising reductions in the consumption of drinking water, namely from 20% to 60% [27] [28] [29] [30] . Combining these two strategies (greywater reuse and domestic water-saving systems) enhances the positive impact: Baskaran et al. [31] found savings of up to 77% relative to normal consumption. It is important to mention that these strategies entail benefits from an economic standpoint for cities, regions, and countries, as well as individuals. Bogotá, Colombia's capital and largest urban center, has more than eight million inhabitants and essentially requires the implementation of such strategies. The treatment of water for human consumption in the city is led by a public company whose primary sources are rivers, dams, and gullies; the company has achieved full (100%) coverage. The drinking water supply comprises three systems (Tibitoc, Chingaza, and La Regadera), which have five drinking water treatment plants (DWTP) and present an installed capacity of 27.5 m 3 /s, of which 53% is used. Groundwater represents an insignificant source and is mostly used by industrial and commercial sectors. The city's public sewage system has achieved coverage exceeding 90%. This system comprises four sanitary catchments, as can be observed in Figure 1 ; these catchments bear the names of the four principal rivers in Bogotá: Torca, Salitre, Fucha, and Tunjuelo. Within these catchments, there are a total of 65 subcatchments, which are subdivided into 49 sanitary subcatchments and 16 rain subcatchments. Most of the sanitary systems are separated, with only a small portion in the Fucha and Salitre Catchments [32] . Bogotá currently has only one wastewater treatment plant (El Salitre), which is located at the confluence of the Salitre River with the Bogotá River. At present, the El Salitre plant only runs primary treatment and has a treatment capacity of 4 m 3 /s. It receives wastewater from approximately 2,200,000 people in the north of the city, the area circumscribed by the Salitre Catchment. It is important to mention that in Colombia, as is the case for many countries around the world, clear policies for urban water management have not been set forth; for that reason, in a previous study, the authors of this paper underscored the urgent need to carry out activities aimed at conserving water to sustainably supply Bogotá's population. The previous study highlighted alternative sources of water supply, and the authors demonstrated that renewed emphasis should be placed on managing the city's drainage systems and treatment systems, primarily to reduce wastewater, contamination, and runoff. These three aspects should be considered holistically, that is, in tandem, for the design of policies for the management of urban water in line with the principles of IUWM [33] . In this article, the simulated implementation of four strategies (stormwater harvesting, reuse of industrial waters, water-saving technology in residential sectors, and reuse of water from washing machines) for managing urban water in two urban catchments (Fucha and Tunjuelo) are evaluated at
doi:10.3390/w9110858 fatcat:ukkuvcrba5bavf36ushpbsxegq