Seasonal drought prediction for semiarid northeast Brazil: what is the added value of a process-based hydrological model?

Abstract

Abstract. The semiarid northeast of Brazil is one of the most densely populated dryland regions in the world and recurrently affected by severe droughts. Thus, reliable seasonal forecasts of streamflow and reservoir storage are of high value for water managers. Such forecasts can be generated by applying either hydrological models representing underlying processes or statistical relationships exploiting correlations among meteorological and hydrological variables. This work evaluates and compares the performances of seasonal reservoir storage forecasts derived by a process-based hydrological model and a statistical approach. Driven by observations, both models achieve similar simulation accuracies. In a hindcast experiment, however, the accuracy of estimating regional reservoir storages was considerably lower using the process-based hydrological model, whereas the resolution and reliability of drought event predictions were similar by both approaches. Further investigations regarding the deficiencies of the process-based model revealed a significant influence of antecedent wetness conditions and a higher sensitivity of model prediction performance to rainfall forecast quality. Within the scope of this study, the statistical model proved to be the more straightforward approach for predictions of reservoir level and drought events at regionally and monthly aggregated scales. However, for forecasts at finer scales of space and time or for the investigation of underlying processes, the costly initialisation and application of a process-based model can be worthwhile. Furthermore, the application of innovative data products, such as remote sensing data, and operational model correction methods, like data assimilation, may allow for an enhanced exploitation of the advanced capabilities of process-based hydrological models.

Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment, Paraíba, Brazil

“…More than 85% of the area of Paraíba State is considered semiarid, and this state has historically suffered from constant periods of drought due to the position of the intertropical convergence zone, the El Niño-Southern oscillation and sea surface temperature, which are interrelated mechanisms that cause variability in rainfall and weather (Alves et al 2017). The behavior of rainfall in time and space in this basin directly influences the water volume in the reservoirs within the region; furthermore, the semiarid northeastern Brazil is one of the world's most densely populated dryland regions (Pilz et al 2018). In addition, severe drought events might deplete the drinking water supply, as has occurred in recent continuous dry years (2012)(2013)(2014)(2015)(2016)(2017).…”

How to Tailor My Process‐Based Hydrological Model? Dynamic Identifiability Analysis of Flexible Model Structures

“…This multiscale feature puts particular emphasis on dryland hydrological peculiarities, such as evaporation from patchy vegetated surfaces, channel transmission losses, infiltration excess in case of crusted soil, and limited connectivity of runoff phenomena (see Bronstert et al, 2014 for more details). The model has been successfully applied in the present study area as well as several other dryland regions in Spain (Bronstert et al, 2014; Francke, Baroni, et al, 2018; Mueller et al, 2009, 2010), Brazil (de Araújo & Medeiros, 2013; Krol et al, 2011; Medeiros et al, 2010, 2014; Pilz, Delgado, et al, 2019), and India (Jackisch et al, 2014). Therefore, it has been chosen as highly plausible model hypothesis for the selected study area and enhanced by further process representations and ODE solvers within ECHSE.…”

Rivers’ Temporal Sustainability through the Evaluation of Predictive Runoff Methods

“…They have implemented simulation models for being applied to hydrographic basins and then are compared to observational data records to get a good calibration. Those models follow the traditional hydrological scheme of procedure of routing for getting the final product of hydrographs [25][26][27][28].…”