Model development for a water supply catchment in southeast Brazil

Brazil faced a severe water crisis during the mid-2010s, resulting in water scarcity and water rationing in various cities. The Belo Horizonte Metropolitan Region was seriously affected. It is located in the southeastern part of the country and home to roughly 5 million people (Costa et al., 2015) and mining industry. The region’s water supply relies on a complex and integrated system, which combines a water abstraction at the Velhas river and three reservoirs. One of these reservoirs, named Serra Azul, reached a minimum of only 5,4 % of its total capacity during the crisis. Here, we demonstrate tools for improving the water management in this area, by developing a hydrological model suitable for mountainous regions with tropical climates. Our case study was the Serra Azul reservoir’s well-gauged catchment. We selected 12 gauges that cover several head waters and rivers section in the 260 km² area.  We used these discharge data (3-5 years), and available static catchments' attributes (e.g. subsurface properties), to adapt a flexible framework for conceptual hydrological modeling. Hence, we identified a suitable model structure using SUPERFLEX (Fenicia et al., 2014). The findings show that by including soil type, lithology and land cover as explanatory variables in the model, we obtained significant improvements in performance, e.g. the correlation between the base flow index estimated for observed and simulated time-series increased from 0.40 to 0.76. We also accounted for groundwater contributions to the streamflow, modelling the relation between the percentage of porous aquifer within each catchment and its flow magnitude. Thereby, we improved the average NSE and timeseries correlation considerably.  Overall, we successfully set up a parsimonious hydrologic model for water resources management in a region that is notoriously difficult to predict, where anthropic activities such as mining and agriculture have a decisive impact on the water cycle.

 

References:

Costa et al. Caracterização e Quadros de Análise Comparativa da Governança Metropolitana no Brasil: análise comparativa das funções públicas de interesse comum (Componente 2)-RM do Rio de Janeiro (Relatório de Pesquisa). (2015). Rio de Janeiro: Institute for Applied Economic Research–Ipea.

Fenicia et al. "Catchment properties, function, and conceptual model representation: is there a correspondence?." Hydrological Processes 28.4 (2014): 2451-2467.