This paper aims to develop a multi-criteria decision analysis (MCDA) tool for rainwater harvesting (RWH) on a university campus in Bogota, Colombia. The specific type of MCDA our research proposes is known as CRIDE (multi-CRIteria DEcision support tool), which allows us to study various methods of RWH. In order to account for uncertainties such as the variability of expert opinions and imprecision stemming from the different criteria required, we have designed this tool to incorporate ELECTRE II and the Monte Carlo method. For this case study we apply a methodology that evaluates the performance of six RWH scenarios. These six input scenarios emerged from an ideal one, wherein all rainwater throughout the campus is successfully harvested and treated until potable. From there, reality sets in: the other five scenarios are varying degrees of deviance from the ideal one, both in terms of water quantity and quality. In regard to collection and treatment we used sustainable urban drainage systems (SUDS). As for the evaluation of each of the scenarios, we outline eight criteria, which include hydraulic performance, compatibility with the University's Master Plan and financial aspects. Our research concludes that CRIDE as a means of support during the decision-making process generates a complete view of possible solutions, in addition to ranking these solutions. The CRIDE-based approach allows for the proposal of a methodology that evaluates the relevance of an established criteria set, using robustness, redundancy and sensitivity.

In peri-urban areas of Bogota, people harvest and use untreated rainwater. Initial research indicates that water collected from roofs contains high turbidity values, as well as high concentrations of total suspended solids, biochemical oxygen demand 5-Day and heavy metals. Moreover, these areas do not generally have access to public sewer systems. An eco-productive green roof with the aim of reducing poverty and improving the quality of life of the communities located peri-urban areas of Bogota has been described and examined. These eco-roofs are made with cheaply attainable materials (e.g. recycled plastic bottles). The aim of this study was to understand the hydrological benefits of this type of green roof. We built an experimental setup consisted of six independent eco-roof modules planted with different crop plant species and a reference roof to serve as a control. The results obtained showed that the crop type had significant influence over the results of both hydrological behaviour and pollutant concentrations measured on the runoff from roofs. The eco-roof can retain up to 65% of the runoff volume and can reduce the runoff peak up to 80%; the eco-roof helped in retaining high concentrations of zinc. The results obtained represent a meaningful positive impact for the eco-roofs tested for stormwater harvesting and suggest that these systems could offer hydrological benefits that might help re-establish hydrological values for marginal urban areas.

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Objective: This paper aims to assess cases where it is necessary to include uncertainties in decision-making input data. Materials and Methods: Three case studies with different numbers of alternatives and different numbers and natures of criteria were evaluated. The CRIDE tool [39] was used to include uncertainties in the input data. Results and Discussion: The results obtained showed that for more difficult decision-making problems, the inclusion of variations in input data could change the final decision, while for less challenging problems, it is unnecessary to take uncertainties into account. Conclusions: These findings could be useful for decision-makers in obtaining more accurate results or in saving time and money related to input data acquisition.