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Assessment of Two Different Methods in Predicting Hydrological Drought from the Perspective of Water Demand
- de Medeiros, Giovana Cristina Santos, Maia, Adelena Gonçalves, de Medeiros, Joana Darc Freire
- Water resources management 2019 v.33 no.5 pp. 1851-1865
- basins, drought, prediction, watersheds, Brazil
- The traditional methodologies to determine hydrologic drought use standardized drought indexes, which do not express a drought’s severity in terms of the volume deficit and do not consider water demand as a component of its calculation. To overcome these disadvantages, this work presents a method for the assessment of hydrological drought that determines the volume of water below its demand. A drought can be characterized by its duration, severity and magnitude, using the Threshold Level Method. Complementarily, the method for the assessment of hydrological drought developed by Araújo and Bronstert (2016) was used to compare the characteristics of drought events in the same reservoirs. For this purpose, the droughts that occurred between 1997 and 2015 were studied in two reservoirs in the Piranhas-Açu River basin (Brazil). For both methodologies, the results showed that the reservoir with a higher storage capacity is more efficient and, thus, less susceptible to drought than the smaller. It was found that the basic difference between the two approaches is the time analysis of drought events: while the Threshold Level Method makes it possible to study what occurred in the past to diagnose and plan the use of water in the future, the other method enables the assessment of current conditions to anticipate the start of a hydrologic drought. It is suggested that the two methodologies presented can be used simultaneously by water resource managers to enable a more comprehensive analysis of drought events in the basin.