The 2018 Henry Darcy Medal is awarded to Alberto Montanari for his physically based stochastic modelling and the major impact this had on water-resources engineering and management.
Alberto Montanari is well known for his physical-stochastic modelling approach. In 2004, he proposed a new paradigm of estimating uncertainties. The novelty of his approach lies in treating uncertainties as an inherent property of the hydrological system by framing the probability distribution of the runoff model error as a function of simulated runoff. The approach thus combines the best of two worlds, the process-based approach based on balance equations of mass, momentum and energy, and the stochastic approach based on random variables. The elegance of this concept is that it automatically includes uncertainty assessment. Montanari was the first to recognise the important linkages among predictive uncertainties from model inputs, model predictions and model processes. The impact of the combined set of papers from this research focus was immense with more than 500 citations in the Web of Science. This new approach had an immediate impact on the practice of water resources engineering, as exemplified by its application in the safe construction of the Grand Ethiopian Renaissance Dam, the largest hydroelectric power plant in Africa.
The next important step was the extension of this stochastic framework to understanding hydrologic change. The key idea, outlined in his 2012 Water Resources Research (WRR) paper, was to allow the probabilistic structure of the predictive error to evolve in time. This relaxed the usual requirement of stationary model errors and made the model applicable to a much wider, more realistic set of problems, such as evaluating climate change impacts on flood frequency distributions, including a full evaluation of uncertainties. This development has also been adopted enthusiastically by the water management practice.
Montanari has also reached out well beyond the hydrological community with his brilliant idea of analysing satellite night-time lights to track settlement patterns over time and understand hydrological change. The response to this body of research was immense, including a WIRED-Science Graphic of the Week. Data on changing settlement patterns allow the testing of his non-stationary stochastic model not only in time, but also in a spatial mode.
Montanari has served the hydrological community in many ways, including as President of the EGU Hydrological Sciences Division (2008-2011), EGU Awards Committee Chair (2009-2016), Editor-in-Chief of WRR (2013-2017), and as the intellectual cornerstone of the Panta Rhei scientific decade of the International Association of Hydrological Sciences (2013-2022). Given his service to the community and impact on water resources engineering, Montanari is a deserving recipient of the 2018 Henry Darcy Medal.