UNCERTAINTY AND SENSITIVITY ANALYSIS IN THE MODELING OF RAIN WATER HARVEST SYSTEMS: INFLUENCE OF DIFFERENT CLIMATE REGIMES
Rainwater tank; performance index; rainfall regime
The use of rainwater is an ancient and still current solution to improve access to water, especially in remote areas with low water availability. However, in order for rainwater harvesting systems to perform satisfactorily, it is necessary that several design variables, such as: water demand, harvesting area, rainfall regime and reservoir volume, be determined with the greatest precision possible. The study of the efficiency of the Rainwater tanks, in meeting their demands, is carried out through computer models, where the water budget is simulated. However, the results obtained in the models do not faithfully represent the real systems, mainly due to the inherent uncertainties in the model's input data. Thus, it is necessary to investigate the errors associated with the results obtained by these models, and for this, uncertainty analysis can be used. Through this analysis, the performance of the rainwater harvesting system is determined considering the uncertainties associated with the input parameters. Another analysis normally studied together with the uncertainty analysis is the sensitivity analysis, which verifies which input parameters most interfere in the output variable (system performance). In previous studies, such as Silva and Ghisi (2016), some design variables, such as reservoir volume, demand and roof area, were analyzed, however, in addition to these variables, there is a need to investigate the uncertainty analysis of the systems of rainwater harvesting in different climatic zones. Thus, the objective of this research is to perform uncertainty and sensitivity analyzes of the efficiency of rainwater harvesting systems in different climatic regimes through the water budget of the reservoir. The input data to be analyzed in this study are: tank volume, water demand, roof area and rainfall regime, in different climatic zones. System performance will be analyzed using different performance indices. Thus, the results obtained will serve to know how the input data influence the behavior of the system, depending on the climate regime, and which errors are associated with the processes of obtaining the efficiency of the cisterns, due to the uncertainties inherent to the input data. This information will assist in the planning, design and implementation of rainwater harvesting systems in different locations, with different rainfall regimes.